---
title: "Top 12 Best Spark Plugs for Mercury 2 Stroke Outboard Exposed!"
url: https://midwestmotorcycletraining.com/best-spark-plugs-for-mercury-2-stroke-outboard/
date: 2026-11-05
modified: 2026-11-05
lang: en
author: "admin@midwestmotorcycletraining.com"
description: "Best spark plugs for Mercury 2 stroke outboard reviewed and compared. Discover top picks to boost performance and reliability in your engine."
categories:
  - "Our Picks"
word_count: 5138
---

# Top 12 Best Spark Plugs for Mercury 2 Stroke Outboard Exposed!

Using the wrong spark plugs in a Mercury 2 stroke outboard often leads to poor engine performance, hard starts, or frequent misfires. The best spark plugs for mercury 2 stroke outboard ensure consistent firing and help maintain smooth running even after hours on the water.

Those who rely on their boat for fishing or leisure know how frustrating it can be when the engine doesn't respond as it should, especially in remote locations.

A good spark plug for a 2 stroke outboard typically features a nickel or platinum tip for durability and reliable ignition. The correct heat range is crucial; too hot can cause pre-ignition and too cold can lead to fouling from carbon buildup. The electrode gap usually falls around 0.6 to 0.7 millimeters, allowing optimal spark delivery without excessive wear.

Proper fit is essential for sealing and avoiding compression leaks, so matching thread size and reach with Mercury’s specifications makes a noticeable difference in engine health.

## Need a Quick Check?

| Image | Product | Price |
| ----- | ------- | ----- |
| Our Top Picks 1![](https://m.media-amazon.com/images/I/61wuC8mMbnL._AC_SX569_.jpg) | Quicksilver BU8H Spark Plug | [Check Price](https://www.amazon.com/Quicksilver-13686Q-Semi-Surface-Discharge-Design/dp/B00N6D6MWI/?tag=midwestmotorcycletraining-20) |
| Our Top Picks 2![](https://m.media-amazon.com/images/I/712oL7lCAiL._AC_SY300_SX300_QL70_FMwebp_.jpg) | BDFHYK Iridium 4-Pack | [Check Price](https://www.amazon.com/BDFHYK-Compatible-Outboard-Universal-Replacement/dp/B0DF7BB7SG/?tag=midwestmotorcycletraining-20) |
| Our Top Picks 3![](https://m.media-amazon.com/images/I/61dDPoZZiQL._AC_SX425_PIbundle-6,TopRight,0,0_SH20_.jpg) | NGK BU8H 6-Pack | [Check Price](https://www.amazon.com/NGK-6431-BU8H-Spark-Plug/dp/B0H9MGN3QP/?tag=midwestmotorcycletraining-20) |

## Our Selected Top 12 Spark Plugs for Mercury 2 Stroke Outboard for Every Budget
This list features a range of spark plugs designed specifically for Mercury 2 stroke outboards, catering to different budgets and needs. Each review explains the performance, ideal users, and key advantages and disadvantages to help you make an informed choice.

### 1. Quicksilver NGK BU8H Spark Plug
[![](https://m.media-amazon.com/images/I/61wuC8mMbnL._AC_SX569_.jpg)](https://www.amazon.com/Quicksilver-13686Q-Semi-Surface-Discharge-Design/dp/B00N6D6MWI/?tag=midwestmotorcycletraining-20)Keeping a Mercury 2 stroke outboard running smoothly means having reliable spark plugs that handle carbon buildup and corrosion. Quicksilver NGK BU8H Spark Plug is designed specifically for marine engines, offering durability and consistent ignition.

It's a solid pick for anyone looking to avoid frequent fouling while maintaining easy maintenance.

Installation is straightforward with standard spark plug sockets, making the swap simple without special tools. The copper core efficiently removes heat, which helps in maintaining optimal spark plug performance during regular use. Its semi-surface discharge design helps burn off carbon deposits before they can cause trouble, so day-to-day you’ll notice less fouling and smooth starts.

The spark plug delivers consistent ignition, helping the engine fire up reliably every time. It’s built with NGK trivalent metal plating that resists corrosion in salty marine conditions, which means fewer worries about rust or seizing when it's time for a change.

Some mention that while it keeps fouling down, it doesn’t completely eliminate the need for occasional checks, though most find it dependable over long runs.

Burning off carbon before it builds up is a clear advantage for these spark plugs, and the anti-corrosion plating stands out in marine use. Some users find they still need to check the plugs periodically to deal with leftover carbon, so it’s not a one-time fix.

Those running Mercury 2 stroke outboards who want easy maintenance and corrosion resistance will appreciate this spark plug. Engines in harsher environments or with heavy use may need to consider plugs with even stronger fouling prevention or multi-pack options.

#### Pros

- Semi-surface discharge design reduces carbon buildup
- NGK trivalent plating prevents corrosion and seizing
- Copper core helps maintain efficient heat removal
- Easy to install with common spark plug sockets

#### Cons

- Does not fully eliminate need for carbon cleaning
- Single pack may require buying multiples for multiple plugs

| Specification | Details |
| ------------- | ------- |
| Brand Name | Quicksilver |
| Manufacturer Part Number | 13686Q |
| Model Number | 13686Q |
| Number of Items | 1 |
| Included Components | Spark Plug (1) |
[Check Price](https://www.amazon.com/Quicksilver-13686Q-Semi-Surface-Discharge-Design/dp/B00N6D6MWI/?tag=midwestmotorcycletraining-20)
### 2. BDFHYK Iridium Spark Plugs Replacement 4-Pack
[![](https://m.media-amazon.com/images/I/712oL7lCAiL._AC_SY300_SX300_QL70_FMwebp_.jpg)](https://www.amazon.com/BDFHYK-Compatible-Outboard-Universal-Replacement/dp/B0DF7BB7SG/?tag=midwestmotorcycletraining-20)Iridium construction ensures faster and more sensitive ignition for Mercury 2-stroke outboards. Suited for models ranging from 6 to 225 HP, the BDFHYK Iridium Spark Plugs deliver reliable power and energy savings, making them an excellent choice for routine maintenance.

Installation is straightforward, given these plugs come with housing. They’re designed to fit a wide range of Mercury outboards, including 6, 8, 40, 50, 115, 125, and more, without requiring adjustments.

Daily use shows stable ignition performance and reduced energy consumption, which aligns with the efficient power delivery needed on the water.

Performance-wise, the plugs provide a significant boost in power and quicker ignition jumps, thanks to iridium's properties. Built with quality in mind, they meet OE standards and come with a one-year warranty, promising durability. The most frequent complaint from reviews revolves around occasional fitment issues on very specific engine versions.

Ignition is noticeably faster and more reliable in daily use, providing consistent power improvements. Some users find occasional difficulties aligning the plug with less common Mercury outboard engine models, reflecting a slight compatibility challenge.

Perfect for anyone with a mid-range Mercury 2-stroke outboard who needs spark plugs that are both reliable and efficient. Those with very specialized models might want to verify compatibility carefully or consider alternatives with broader fit guarantees.

#### Pros

- Superior ignition performance
- Compatible with many Mercury outboards
- OE standard durability
- Includes housing for easier installation

#### Cons

- Fit issues on some specific engine versions
- Limited warranty period of 1 year

| Specification | Details |
| ------------- | ------- |
| Brand Name | BDFHYK |
| Compatibility | Mercury 6 8 40 50 115 125 20 30 40 45 55 60 80 Jet Sea Pro 225 2-Stroke |
| Manufacturer Part Number | BD-05-10838-4-SP |
| Number of Items | 4 |
| OEM Equivalent Part Number | BPZ8HN10 |
| Manufacturer Warranty | 1 year |
[Check Price](https://www.amazon.com/BDFHYK-Compatible-Outboard-Universal-Replacement/dp/B0DF7BB7SG/?tag=midwestmotorcycletraining-20)
### 3. NGK BU8H Spark Plug 6-Pack
[![](https://m.media-amazon.com/images/I/61dDPoZZiQL._AC_SX425_PIbundle-6,TopRight,0,0_SH20_.jpg)](https://www.amazon.com/NGK-6431-BU8H-Spark-Plug/dp/B0H9MGN3QP/?tag=midwestmotorcycletraining-20)Ideal for anglers and boaters running Mercury and Mariner 2-stroke outboards, these spark plugs promise reliable ignition with easy fitment. Their biggest strength lies in delivering consistent engine starts and smooth running thanks to the premium surface gap electrode design.

Setting them up is straightforward as they come in a six-pack, perfect for multiple replacements or backups. The non-resistor, surface discharge type construction means they spark efficiently without fuss. Compatibility across many Mercury and Mariner models makes them a convenient choice for anyone maintaining these engines regularly.

They handle ignition duties well, ensuring steady engine performance during boating sessions. Built with OEM NGK quality, these plugs offer durability and extended service life. Most praise highlights their consistent firing ability, while the few drawbacks mention occasional fitment needing careful threading to avoid cross-threading in older engines.

Consistent ignition and extended service life stand out as strong benefits, making this spark plug dependable on the water. Common concerns revolve around fitment in older engines needing careful threading to prevent damage.

Those running compatible Mercury or Mariner 2-stroke outboards will find these spark plugs reliable and easy to source in bulk. Users with very specific resistor plug needs or unusual engine configurations might want to consider alternatives tailored to those requirements.

#### Pros

- Fits a wide range of Mercury and Mariner engines
- Offers reliable ignition with premium electrode design
- Comes in a convenient 6-pack for multiple uses
- OEM NGK quality ensures long service life

#### Cons

- Fitment can occasionally be tricky, requiring care
- No resistor type, which some engines may prefer

| Specification | Details |
| ------------- | ------- |
| Manufacturer Part Number | BU8H |
| OEM Equivalent Part Number | Mercury Marine 33-13686B, 33-13686Q |
| Type | Non Resistor, Surface Discharge |
| Pack Quantity | 6 |
| Compatible with Mercury Models | 105 Jet, 135, 150, 175 EFI, 200 EFI, 225, 250 3.4L, 275, 300 |
[Check Price](https://www.amazon.com/NGK-6431-BU8H-Spark-Plug/dp/B0H9MGN3QP/?tag=midwestmotorcycletraining-20)
### 4. Iridium Spark Plugs Replacement 8-Pack
[![](https://m.media-amazon.com/images/I/61rD1UqSeAL._AC_SX425_PIbundle-8,TopRight,0,0_SH20_.jpg)](https://www.amazon.com/Iridium-Evinrude-Outboard-Replacement-QL78YC/dp/B0FGCMMK4X/?tag=midwestmotorcycletraining-20)Iridium Spark Plugs Replacement 8-Pack fits a wide range of Mercury 2 stroke outboard engines and stands out for its reliable compatibility and durable iridium construction. Ideal for anyone needing a trustworthy plug match for models from 9.9 HP to 200 HP, it brings steady performance with minimal fuss.

Installing the plugs is straightforward thanks to their exact fit for many Mercury Marine engines and related brands like Johnson and Evinrude. Having eight plugs in one pack means you’re set for multiple replacements or a full engine tune-up.

These plugs handle daily rides on the water without requiring frequent cleaning or adjustment, maintaining efficient ignition across varied conditions.

The iridium tip delivers consistent spark quality that supports smooth engine starting and running. Built solid and replacing the OEM 938M model, the plugs last well under normal usage. Most users appreciate the durability and fit, while some have noted occasional variability between packs or shipping delays.

The iridium spark plugs are praised for their durability and fit across many Mercury 2 stroke outboards, making engine starts reliable. Common drawbacks include occasional quality inconsistencies between different packs and reports of slow shipping times. Maintenance tends to be low effort with these plugs.

Anyone running a Mercury or compatible Johnson or Evinrude 2 stroke outboard engine from 9.9 HP to 200 HP will find these plugs a solid match. Those who need the absolute highest-quality plug or faster delivery options might consider exploring alternatives.

#### Pros

- Fits wide range of Mercury and related engines
- Long-lasting iridium electrode
- Comes in a pack of eight
- Direct OEM replacement part

#### Cons

- Some variability in quality between packs
- Shipping delays reported occasionally

| Specification | Details |
| ------------- | ------- |
| Brand Name | yeeluzan |
| Manufacturer Part Number | QL78YC |
| Number of Items | 8 |
| OEM Equivalent Part Number | QL78YC |
| Manufacturer Warranty | 1 year |
| Item Weight | 15.04 ounces |
[Check Price](https://www.amazon.com/Iridium-Evinrude-Outboard-Replacement-QL78YC/dp/B0FGCMMK4X/?tag=midwestmotorcycletraining-20)
### 5. NGK ZFR5F Spark Plugs 4-Pack
[![](https://m.media-amazon.com/images/I/514aU07GMeL._AC_SX425_PIbundle-4,TopRight,0,0_SH20_.jpg)](https://www.amazon.com/NGK-7558-Replaces-8M0035043-98079-5587G/dp/B072B5R37H/?tag=midwestmotorcycletraining-20)NGK ZFR5F Spark Plugs 4-Pack suits Mercury 2 stroke outboard engines looking for dependable ignition. Its biggest strength lies in consistent ignition performance that ensures your motor starts smoothly and runs reliably under normal conditions.

Installing these spark plugs is straightforward since they match OEM specifications and replace several part numbers commonly used in Mercury outboards. The corrosion-resistant trivalent metal plating helps prevent rust buildup and makes removal easier over time.

Daily operation benefits from the advanced electrode design, promoting efficient combustion and stable power delivery without frequent replacements.

Built with application-specific electrode technology, the plugs maintain reliable sparks which support smooth engine running. The copper, iridium, or platinum electrodes offer durability matched to typical fishing or cruising needs.

Most praise centers on how consistently the engine starts and runs, while complaints often mention occasional difficulties in removal if left too long without maintenance.

Ignition reliability stands out as the main benefit, with smooth and consistent engine operation being the key feature. A common downside involves some hassle removing the plugs after extended periods, despite the corrosion-resistant plating.

Those who value dependable starts and standard engine performance during regular boating will find these plugs fitting well. Users needing plugs for heavy-duty or extended rough use may want to consider alternatives better suited for those demands.

#### Pros

- Consistent ignition for smooth engine starts
- Corrosion-resistant trivalent metal plating
- Replaces multiple OEM part numbers
- Durable electrode design for long use

#### Cons

- May be difficult to remove after long use
- Only suitable for normal driving conditions

| Specification | Details |
| ------------- | ------- |
| Brand Name | NGK |
| Manufacturer Part Number | 7558 |
| Number of Items | 4 |
| OEM Equivalent Part Number | 7558 |
| Item Weight | 6.4 ounces |
| Manufacturer Warranty Description | Includes manufacturer provided warranty |
[Check Price](https://www.amazon.com/NGK-7558-Replaces-8M0035043-98079-5587G/dp/B072B5R37H/?tag=midwestmotorcycletraining-20)
### 6. BU8H Non-Resistor Spark Plugs 6-Pack
[![](https://m.media-amazon.com/images/I/61vjwsGUvBL._AC_SX425_PIbundle-6,TopRight,0,0_SH20_.jpg)](https://www.amazon.com/Generic-Non-Resistor-Pre-Gapped-Compatible-BU8H-6PK-01/dp/B0D4C25VTN/?tag=midwestmotorcycletraining-20)Running a Mercury 2 stroke outboard feels smoother when the spark plugs fire reliably every time. These BU8H non-resistor plugs suit anyone wanting a straightforward replacement that fits well and keeps their engine running consistently without fuss. Their biggest strength lies in providing solid performance with an easy-to-install design.

Installing the plugs is simple since they come in a pack of six and match the OEM BU8H number exactly. Using them day to day means less worry about misfires or starting problems, as they maintain steady ignition. Their non-resistor design keeps things basic, perfect for those focused on dependable operation rather than extra features.

These plugs deliver consistent spark performance and hold up well under regular conditions. They are built with expected OEM specifications and materials, fitting Mercury 2 stroke models without issues.

Strong praise highlights how reliable and straightforward they are, while a common complaint mentions a lack of detailed warranty information from the manufacturer.

The strongest positive feedback emphasizes the ease of fit and steady performance these plugs provide in daily use. The main drawback noted is the lack of any specified warranty, which may concern users wanting official coverage.

Those seeking an OEM-equivalent replacement that installs easily and runs steadily will find these plugs a solid choice. Those wanting additional features or warranty assurance might look elsewhere.

#### Pros

- Matches OEM BU8H specification precisely
- Comes as a convenient six-pack
- Simple non-resistor design for reliability
- Fits Mercury 2 stroke outboards well

#### Cons

- Manufacturer warranty details not specified
- Generic brand may cause hesitation for some

| Specification | Details |
| ------------- | ------- |
| OEM Part Number | BU8H (6431) |
| Unit Count | 6 Count |
| Item Type Name | Spark Plug |
| Manufacturer | JSI |
| Manufacturer Part Number | BU8H-6PK-01 |
[Check Price](https://www.amazon.com/Generic-Non-Resistor-Pre-Gapped-Compatible-BU8H-6PK-01/dp/B0D4C25VTN/?tag=midwestmotorcycletraining-20)
### 7. Quicksilver Spark Plug Wire Lead
[![](https://m.media-amazon.com/images/I/41sIjdpQECL._AC_SX569_.jpg)](https://www.amazon.com/Quicksilver-821945A61-Select-Mercury-Outboards/dp/B0BF63QCRW/?tag=midwestmotorcycletraining-20)Quicksilver Spark Plug Wire Lead suits Mercury or Mariner 2-stroke outboards from 30 to 300hp, including EFI, carbureted, and jet models. Its biggest strength lies in being a direct OEM replacement, ensuring compatibility and straightforward installation for various engine setups.

Installation requires only common shop tools, which makes setting it up pretty straightforward. The wire fits engines with 2 to 4 cylinders, and it works across different fuel delivery systems, which keeps things simple for routine maintenance. Day-to-day, the wire holds up without fuss and doesn’t add noticeable weight or bulk around the engine bay.

It performs reliably in carrying the spark current, crucial for smooth engine firing. The build is solid, typical of parts labeled Quicksilver, with a sturdy black cable housing.

Praise often centers on the easy replacement and perfect fit. A noted complaint is not having multiple wires in a single pack, meaning you might need to buy more for multi-cylinder engines.

The product is praised for its perfect fit and ease of installation on a wide range of Mercury 2-stroke engines. Most users note the convenience of having a genuine OEM equivalent cable but mention the inconvenience of having to purchase multiple wires separately for multi-cylinder engines.

Those replacing a single wire in common Mercury or Mariner 2-stroke outboards will find it suitable. For complete multi-cylinder rewiring, consider buying several or a multi-pack to avoid multiple purchases. People seeking comprehensive kits will want to look for other options that include multiple wires in one package.

#### Pros

- Direct fit for Mercury/Mariner 2-stroke engines
- Simple installation with standard tools
- Works for EFI, carbureted, and jet outboards
- Lightweight at 27.22 grams

#### Cons

- Only one wire included per pack
- No specific instructions included in package

| Specification | Details |
| ------------- | ------- |
| Brand Name | Quicksilver |
| Manufacturer Part Number | 821945A61 |
| Number of Packs | 1 |
| Number of Items | 1 |
| OEM Equivalent Part Number | 821945A61 |
| Item Weight | 27.22 g |
[Check Price](https://www.amazon.com/Quicksilver-821945A61-Select-Mercury-Outboards/dp/B0BF63QCRW/?tag=midwestmotorcycletraining-20)
### 8. NGK BU8H Standard Spark Plug
[![](https://m.media-amazon.com/images/I/71sy-UeMeyL._AC_SX425_.jpg)](https://www.amazon.com/NGK-33-13686Q-33-13686B-Dependable-electrodes/dp/B0000AXR7E/?tag=midwestmotorcycletraining-20)Copper core design stands out for delivering a stronger spark, making it a solid choice for Mercury 2 stroke outboards. The NGK BU8H fits well for those looking to reduce fouling and limit corrosion in marine engines. Its long insulator nose helps keep it running cleaner, which is ideal for consistent performance.

Setting up involves swapping out your old plugs with one that directly fits, designed specifically for your Mercury outboard. The longer insulator nose keeps fouling at bay, so you don’t have to clean or replace it too often. Zinc dipped shell and triple gasket seal help with corrosion resistance and prevent combustion leaks, meaning less maintenance hassle over time.

Performance is dependable with nickel electrodes that maintain the spark needed for smooth operation. Build quality stands up well against corrosion thanks to its zinc dipped shell, and the triple gasket seal is effective in eliminating combustion gas leakage. Most praise highlights its reliability, while some mention that it may not outperform high-end or iridium plugs in extreme conditions.

Reliability is praised for producing a consistent spark and resisting corrosion in marine environments. However, some mention that it does not outperform premium plugs, especially under demanding conditions.

Ideal for those wanting standard performance with corrosion-resistant features on Mercury 2 stroke outboards. Users seeking maximum durability or advanced materials should look for higher-end options instead.

#### Pros
- Solid copper core for stronger spark- Long insulator nose reduces fouling- Zinc dipped shell guards against corrosion- Triple gasket seal stops combustion leaks
#### Cons
- Not as durable as higher-end iridium plugs- Only available as single pack, not multi-packs
| Specification | Details |
| ------------- | ------- |
| Brand Name | NGK |
| Manufacturer Part Number | BU8H |
| OEM Equivalent Part Number | 6431 |
| Item Weight | 1.44 ounces |
| Included Components | Spark Plug (10) |
[Check Price](https://www.amazon.com/NGK-33-13686Q-33-13686B-Dependable-electrodes/dp/B0000AXR7E/?tag=midwestmotorcycletraining-20)
### 9. NGK BP8H-N-10 Spark Plugs 4-Pack
[![](https://m.media-amazon.com/images/I/71zv+n6hshL._AC_SY879_PIbundle-4,TopRight,0,0_SH20_.jpg)](https://www.amazon.com/NGK-4838-BP8H-N-10-33-816737Q-33-816737B/dp/B00WF9MBX8/?tag=midwestmotorcycletraining-20)NGK BP8H-N-10 spark plugs come as a 4-pack designed for Mercury 2 stroke outboards, offering reliable fitment and durability. Their standout feature is the V-groove nickel tip that focuses the spark for better combustion, making them a solid choice for maintaining engine performance.

Installing these plugs is straightforward as they replace specific Mercury parts like 33-816737Q and 816 737 B2. Day-to-day use benefits from their OEM build quality, designed to last longer and keep your outboard running smoothly. The consistent spark helps keep the motor starting with ease, avoiding the trouble of misfires or weak performance.

Power delivery meets expectations with a steady, focused spark that ensures efficient combustion, crucial for two-stroke engines. Built with nickel tips featuring a V-groove, these plugs provide durability suited for marine conditions.

The most frequent praise highlights dependable engine starts, though some mention they wear out sooner than anticipated.

The spark plugs deliver reliable engine starts and maintain steady performance thanks to the concentrated spark design. Many appreciate their fit for Mercury 2 stroke engines, but several experiences note quicker wear under heavy use, which might mean more frequent replacements.

Those running Mercury 2 stroke outboards who need exact OEM replacements will find these plugs suitable. For those seeking extremely long-lasting plugs or extra installation support, other options might be better fit.

#### Pros

- Replaces several Mercury OEM parts accurately
- V-groove tip concentrates spark effectively
- Nickel tip offers decent longevity
- Pack of four suits regular maintenance needs

#### Cons

- Some people notice the plugs wear out quickly
No included installation components or guide

| Specification | Details |
| ------------- | ------- |
| Brand Name | NGK |
| Tip Material | Nickle with V-groove |
| Manufacturer Part Number | 41-BP8HN10 |
| Unit Count | 4 Count |
| OEM Equivalent Part Number | 816 737 2-MERCURY, 816 737 B2-MERCURY, 816 737 Q-MERCURY, 8M0176615-MERCURY |
[Check Price](https://www.amazon.com/NGK-4838-BP8H-N-10-33-816737Q-33-816737B/dp/B00WF9MBX8/?tag=midwestmotorcycletraining-20)
### 10. Iridium Spark Plugs QL78YC 4-Pack
[![](https://m.media-amazon.com/images/I/71lNHrNZeKL._AC_SX425_PIbundle-4,TopRight,0,0_SH20_.jpg)](https://www.amazon.com/SYKRSS-Evinrude-Outboard-10HP-225HP-1973-2001/dp/B0FLXSX6JN/?tag=midwestmotorcycletraining-20)Offering a direct replacement for OE QL78YC, these iridium spark plugs suit Mercury 2 stroke outboards from various years and models. Their biggest strength lies in durability thanks to materials designed to resist extreme heat, ensuring consistent ignition over time, making them a solid choice for those wanting dependability over a cheap quick fix.

Installation matches original equipment standards, simplifying swap-outs on compatible engines including Mercury/Mariner EFI Sport and Super Magnum series. Day-to-day use reveals steady performance without frequent fouling or misfires, supported by high-temperature resistance.

Maintenance is minimal since the iridium tip stays intact under thermal stress, which means fewer tune-ups just to replace worn plugs.

Power delivery stays consistent with clean, reliable sparks firing at the right timing. The build quality reflects materials meant for heat endurance, holding up to tough marine conditions effectively. Positive notes mention sustained engine smoothness, while negativity often points to compatibility questions due to the wide range of supported Mercury and Johnson models.

Consistent engine smoothness and reliable ignition are praised most often, while confusion about fitting the right engine model is the main complaint. The iridium tip’s heat resistance reduces replacement frequency compared to standard plugs.

Those running compatible Mercury or Johnson 2 stroke outboards valuing durability and reliable starting will appreciate these plugs. Users with less common or newer model engines should verify fit carefully before purchase.

#### Pros

- High-temperature resistant materials
- Direct OE replacement fit
- Works on multiple Mercury and Johnson engines
- Includes 4 spark plugs per pack

#### Cons

- Compatibility can be confusing across many engine models
- One-year warranty might feel short to some users

| Specification | Details |
| ------------- | ------- |
| Number of Items | 4 |
| Compatible Engine Range | 10HP-225HP (1973-2001) |
| OEM Equivalent Part Number | QL78YC |
| Manufacturer Part Number | SY10867-4-SP002 |
| Brand Name | SYKRSS |
| Manufacturer Warranty | 1 Year |
[Check Price](https://www.amazon.com/SYKRSS-Evinrude-Outboard-10HP-225HP-1973-2001/dp/B0FLXSX6JN/?tag=midwestmotorcycletraining-20)
### 11. Spark Plugs DCPR6E 2-Pack
[![](https://m.media-amazon.com/images/I/51-2W7-XhRL._AC_SX425_.jpg)](https://www.amazon.com/Micro-Traders-Outboard-Compatible-Mariner/dp/B0FG7N2WJ1/?tag=midwestmotorcycletraining-20)Outboard engine misfires or rough starts can be frustrating when you're out on the water, especially with Mercury 2 stroke motors. Designed for these engines, the Spark Plugs DCPR6E 2-Pack offers reliable ignition that keeps your boat running smoothly.

It’s a solid choice for anyone needing consistent performance in demanding marine conditions.

Installing these plugs is straightforward thanks to the standard 12mm thread size and an overall length of 75.5mm that fits well in Mercury outboard motors. The pack includes two plugs, making it convenient to replace both cylinders at once.

These plugs focus on durable ignition performance, so you can count on smoother running engines and better fuel combustion every time you start your boat.

Fuel burns efficiently with these spark plugs, which means your engine runs cleaner and more reliably. Built to withstand harsh marine environments, they resist corrosion and wear, helping maintain ignition quality through many hours on the water.

Reviews note that ignition reliability is strong, though some mention occasional fitment concerns, which makes double-checking engine compatibility important before purchasing.

Strong ignition reliability is the main strength highlighted in reviews, keeping Mercury 2 stroke outboards running smoothly. Some users have experienced fitment issues, so confirming engine specifications before buying is advisable to avoid mismatch problems.

Those running compatible Mariner Mercury outboard motors will find these plugs dependable for daily use. Users with less common engine variants or uncertain fitment should consider verifying compatibility or looking for alternatives to avoid installation issues.

#### Pros

- Reliable ignition performance in marine engines
- Suitable for Mariner Mercury models
- Resistant to marine environment wear
- Includes two spark plugs per pack

#### Cons

- Fitment issues reported with some engine models
- Limited to specific Mercury 2 stroke outboards

| Specification | Details |
| ------------- | ------- |
| Thread size | 12mm |
| The total length is 75.5mm.Model numbers | DCPR6E, DCPR6-E, 3481 |
| Package quantity | 2 spark plugs |
| Brand name | Micro Traders |
| Item weight | 2.82 ounces |
[Check Price](https://www.amazon.com/Micro-Traders-Outboard-Compatible-Mariner/dp/B0FG7N2WJ1/?tag=midwestmotorcycletraining-20)
### 12. NGK BU8H Spark Plug 4-Pack
[![](https://m.media-amazon.com/images/I/61CxP8K+JOL._AC_SX425_PIbundle-4,TopRight,0,0_SH20_.jpg)](https://www.amazon.com/Spark-Marine-Outboard-Motor-Boxed/dp/B00YMXAR5O/?tag=midwestmotorcycletraining-20)Ideal for Mercury 2 stroke outboard engines, the NGK BU8H Spark Plug 4-Pack offers a perfect fit with genuine OEM equivalent part numbers. Its biggest strength is reliability in keeping your engine running smoothly without fuss or frequent replacements.

Setting up these plugs is straightforward thanks to matching OEM specs like 136 86 B2-MERCURY and 136 86 Q-MERCURY. Day-to-day use involves consistent ignition performance, crucial for any boating trip.

The set of four ensures you have replacements ready when needed, maintaining engine power without extra maintenance hassles.

Performance shines in its ability to deliver stable sparks essential for two-stroke outboards. The plugs are well-built by NGK, a known manufacturer of boating accessories, and weigh just under 13 ounces for easy handling.

Most users find the plugs reliable and long-lasting, though some mention occasional difficulty with installation in tight engine spaces.

Many users appreciate the reliable spark delivery and compatibility with Mercury engines, ensuring smooth operation. The main issue reported involves the challenge of fitting the plugs in cramped engine compartments, which may require some careful maneuvering or tools.

This spark plug set suits anyone needing direct OEM replacements for their Mercury 2 stroke outboard, especially those who want dependable ignition without frequent changes. Boaters working with very restricted engine access might prefer plugs designed for easier handling.

#### Pros

- OEM-compatible fit for Mercury 2 stroke outboards
- Comes in a convenient 4-pack for replacements
- Lightweight design for easy installation
- Manufactured by trusted NGK brand

#### Cons

- Can be tricky to install in tight spaces
- No detailed instructions included in the pack

| Specification | Details |
| ------------- | ------- |
| Brand Name | NGK |
| Manufacturer Part Number | 41-BU8H |
| OEM Equivalent Part Number | 136 86 B2-MERCURY,136 86 Q-MERCURY,896329885-MERCURY,8M0176682-MERCURY |
| Item Weight | 12.96 ounces |
| Number of Items | 4 |
[Check Price](https://www.amazon.com/Spark-Marine-Outboard-Motor-Boxed/dp/B00YMXAR5O/?tag=midwestmotorcycletraining-20)
## Best Spark Plugs for Mercury 2 Stroke Outboard Comparison

| Product | Brand | Pack Size | OEM Equivalent | Fitment |
| ------- | ----- | --------- | -------------- | ------- |
| **Quicksilver BU8H Spark Plug** | Quicksilver | 1 Count | 13686Q | Mercury 2-Stroke |
| **BDFHYK Iridium 4-Pack** | BDFHYK | 4 Count | BPZ8HN10 | Mercury 2-Stroke Compatible |
| **NGK BU8H 6-Pack** | NGK | 6 Count | 33-13686B/Q | Mercury Marine |
| **Iridium Spark Plugs 8-Pack** | yeeluzan | 8 Count | QL78YC | Mercury Johnson Evinrude |
| **NGK ZFR5F 4-Pack** | NGK | 4 Count | 7558 | - |
| **BU8H Non-Resistor 6-Pack** | Generic | 6 Count | BU8H | - |
| **Quicksilver Wire Lead** | Quicksilver | 1 Count | 821945A61 | Wire Lead, Not Plug |
| **NGK BU8H Standard** | NGK | 1 Count | 6431 | Mercury Marine |
| **NGK BP8H-N-10 4-Pack** | NGK | 4 Count | - | - |
| **Iridium QL78YC 4-Pack** | SYKRSS | 4 Count | QL78YC | Mercury/Johnson/Evinrude |
| **DCPR6E Spark Plugs 2-Pack** | Micro Traders | 2 Count | - | - |
| **NGK BU8H 4-Pack** | NGK | 4 Count | 13686 B2/Q | Mercury Marine |
1. Quicksilver BU8H Spark Plug- **Brand**Quicksilver- **Pack Size**1 Count- **OEM Equivalent**13686Q- **Fitment**Mercury 2-Stroke2. BDFHYK Iridium 4-Pack- **Brand**BDFHYK- **Pack Size**4 Count- **OEM Equivalent**BPZ8HN10- **Fitment**Mercury 2-Stroke Compatible3. NGK BU8H 6-Pack- **Brand**NGK- **Pack Size**6 Count- **OEM Equivalent**33-13686B/Q- **Fitment**Mercury Marine4. Iridium Spark Plugs 8-Pack- **Brand**yeeluzan- **Pack Size**8 Count- **OEM Equivalent**QL78YC- **Fitment**Mercury Johnson Evinrude5. NGK ZFR5F 4-Pack- **Brand**NGK- **Pack Size**4 Count- **OEM Equivalent**7558- **Fitment**-6. BU8H Non-Resistor 6-Pack- **Brand**Generic- **Pack Size**6 Count- **OEM Equivalent**BU8H- **Fitment**-7. Quicksilver Wire Lead- **Brand**Quicksilver- **Pack Size**1 Count- **OEM Equivalent**821945A61- **Fitment**Wire Lead, Not Plug8. NGK BU8H Standard- **Brand**NGK- **Pack Size**1 Count- **OEM Equivalent**6431- **Fitment**Mercury Marine9. NGK BP8H-N-10 4-Pack- **Brand**NGK- **Pack Size**4 Count- **OEM Equivalent**-- **Fitment**-10. Iridium QL78YC 4-Pack- **Brand**SYKRSS- **Pack Size**4 Count- **OEM Equivalent**QL78YC- **Fitment**Mercury/Johnson/Evinrude11. DCPR6E Spark Plugs 2-Pack- **Brand**Micro Traders- **Pack Size**2 Count- **OEM Equivalent**-- **Fitment**-12. NGK BU8H 4-Pack- **Brand**NGK- **Pack Size**4 Count- **OEM Equivalent**13686 B2/Q- **Fitment**Mercury Marine
## How to Choose the Right Spark Plug
Choosing the right spark plug involves considering factors like heat range, electrode material, and compatibility with your engine to ensure reliable ignition and optimal performance. Selecting the best fit helps prevent engine misfires, reduces fuel consumption, and extends engine life, ultimately saving money and avoiding frequent repairs.

### Compatibility with Engine Models
Matching a plug to the exact engine model can prevent a lot of frustration on the water. A plug with the wrong thread size or reach may not seat properly in the cylinder head, which often leads to compression leaks or misfires.

The tick marks that appear on many originals indicate the thread size, usually somewhere between 10mm and 14mm for these motors, while the reach needs to be correct to avoid damaging piston heads or failing to ignite efficiently.

Heat range is another critical feature. Using a plug that is too hot causes pre-ignition and fouling, while a plug that runs too cold will struggle to self-clean, shortening service life.

Most Mercury 2-stroke outboards use a medium heat range. Look for models rated to handle the heat produced by these high-revving engines, which makes a difference in long-term engine health and consistent power delivery.

### Material and Electrode Construction
Longevity in spark plugs for marine engines often depends on the materials and electrode design. Iridium and platinum tips are well-known for lasting significantly longer than standard copper, resisting wear that leads to weaker sparks.

These materials also tend to cope better with the corrosive saltwater environment, a regular challenge for any outboard component.

The shape and number of electrodes affect combustion. Fine-wire designs with tapered or multi-electrode tips offer more consistent ignition and improve fuel burn.

This can translate to smoother acceleration and less unburned fuel. In the harsh marine climate, a plug resistant to corrosion and deposits cuts down on frequent replacements and helps maintain reliable starting and running.

### Performance and Efficiency
The consistency of spark delivery can make or break boat runs. A spark plug that fires irregularly causes rough idling, hesitation under load, and can waste fuel.

Plugs designed for steady performance provide reliable ignition whether the engine is cold or pushed hard on a weekend fishing trip, improving overall efficiency.

Cold starts are easier with plugs that have a clean, strong spark and resist fouling from fuel additives or moisture. Proper spark timing and intensity directly link to getting the engine running smoothly right away, helping avoid the frustration of stalls or crank-only starts.

Few things compare to the benefit of a plug that outright prevents misfires through a wide range of RPMs.

### Durability and Maintenance
Daily use in salt spray and the heat of combustion wears down spark plugs faster than on land engines. A durable plug with wear-resistant electrodes keeps performance steady over time and reduces the hassle of frequent changes. Expect to replace cheaper plugs multiple times each season, whereas better constructions last twice as long under marine conditions.

Maintenance matters because build-up of carbon or fuel residues fouls the plugs and kills spark quality. Some plugs resist fouling better with special coatings or design elements that burn off deposits during operation.

Cleaning is possible but time-consuming and may not restore performance fully. Investing in plugs less prone to fouling saves time and keeps the engine at its best.

### Installation and Handling
Ease of installation is noticeable when replacing plugs on the boat. A plug that fits standard tools with clear torque recommendations avoids stripping the threads or damaging the cylinder head. Proper torque ensures a tight seal that holds compression and prevents water intrusion, essential for marine use.

Good packaging includes clear markings and instructions that identify the right orientation and fitting specs. This reduces mistakes, especially when working in less-than-ideal lighting conditions at the dock.

Plugs housed individually are less likely to get damaged or lose their anti-corrosion coatings before installation.

## Proper Maintenance Practices to Extend the Life of Mercury 2 Stroke Outboard Spark Plugs
The lifespan of spark plugs in a Mercury 2 stroke outboard can be significantly extended by following a few key maintenance steps. Regularly checking the spark plug gap with a feeler gauge ensures the electrode spacing remains within manufacturer specifications, which affects engine performance and fuel efficiency. Cleaning deposits from the plug surface helps prevent misfires and rough idling, especially after long periods of use or storage.

Replacing spark plugs at recommended intervals prevents wear-related issues such as electrode erosion or carbon buildup. Using dielectric grease on the threads improves electrical conductivity and protects against corrosion.

Also, examining the plugs for signs of overheating, fouling, or physical damage during routine engine inspections can help catch potential problems early. **These maintenance tasks contribute to smoother starts, better combustion, and reduced engine strain over time.**

## Common Mistakes to Avoid When Installing Spark Plugs in Mercury 2 Stroke Outboards
Improper installation of spark plugs in Mercury 2 stroke outboards can lead to poor engine performance or damage. A common mistake is over-tightening the plug, which can strip the threads or crack the cylinder head. Using a torque wrench set to the manufacturer’s specifications is necessary to avoid this.

Another frequent error is neglecting to check or reset the spark plug gap before installation, causing misfires or inefficient combustion. Inserting a dirty or damaged spark plug risks contaminating the cylinder and degrading engine reliability.

Skipping the use of anti-seize compound on the threads can make future removal difficult or cause corrosion inside the engine block. Ensuring the spark plug wire boot clicks firmly onto the plug prevents loose connections that cause intermittent firing problems. **Careful attention to these details ensures the engine runs smoothly and reliably.**

## Comparing Spark Plug Alternatives for Different Mercury 2 Stroke Outboard Models
Choosing the right spark plug for different Mercury 2 stroke outboard models depends on engine size, operating conditions, and manufacturer recommendations. Standard copper core plugs work well for smaller or older models, offering good conductivity but requiring frequent replacement. Iridium plugs provide a longer service life with better ignition reliability and can handle higher heat ranges, suitable for performance-oriented or newer engines.

Platinum plugs fall between copper and iridium, offering moderate durability and steady performance. Some models specify a particular heat range or electrode design to optimize combustion and prevent fouling under typical marine use.

It is important to match the spark plug’s specifications to the engine’s requirements stated in the owner’s manual rather than simply choosing based on price or brand. **Using the correct spark plug type helps maintain engine efficiency and reduces the risk of running issues.**

## People Also Asked

### How Do I Choose the Right Spark Plug Size for My Outboard?
Choose the spark plug that matches the specifications listed in your Mercury 2 stroke outboard’s manual. Check the gap size, thread diameter, and heat range to make sure it fits correctly. Using the recommended spark plug ensures proper combustion and engine performance.

### What Is the Proper Way to Install Spark Plugs on a 2 Stroke?
Tighten the spark plug by hand first to avoid cross-threading, then use a torque wrench to the manufacturer’s specified torque. Over-tightening can damage the threads in the cylinder head, while under-tightening might cause poor sealing and misfires.

### How Often Should I Replace Spark Plugs on a Mercury 2 Stroke?
Replace spark plugs every 100 hours or once a season depending on use and condition. Always inspect them for corrosion, fouling, or wear before deciding whether to change them. Clean plugs may work, but new ones keep the engine running smoothly.

### Can Using the Wrong Spark Plug Damage My Outboard Engine?
Using the wrong spark plug can cause poor engine performance or damage the motor. An incorrect heat range or gap size can lead to overheating, misfires, or carbon buildup that reduce efficiency and increase the chances of engine wear.

### What Are Common Spark Plug Problems in 2 Stroke Outboard Motors?
Common problems include fouling from oil or unburned fuel, corrosion from moisture, and wear of the electrode. Regularly checking and cleaning spark plugs helps avoid starting issues and rough running in 2 stroke outboards.

## Conclusion
Choosing the right spark plug for a Mercury 2 stroke outboard depends mainly on compatibility with your engine, durability under wet and high-heat conditions, and ease of installation. Proper electrode design and corrosion resistance also affect performance and how often you need to replace the plugs.

Consider how often you use your boat and your budget when picking a spark plug. Some options last longer but cost more upfront.

Refer back to the comparison table and product details above to find one that fits your needs and engine specifications best.