Choose a spark plug replacement by the exact engine application and approved part number. Match heat range, thread reach, seat, gap and electrode type before comparing platinum, iridium or copper-core designs. The small-engine plugs here need a separate equipment fit check.
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spark plug replacement: specifications and practical limits
| Option | Published details and limits | Listing |
|---|---|---|
| DENSO PK20TT Platinum TT | A Platinum TT plug in the DENSO application catalog. | Check Amazon availability |
| Bosch ZGR6STE2 Copper With Nickel | A copper-core and nickel-electrode plug in Bosch’s catalog. | Check Amazon availability |
| NGK LFR6AIX-11 Iridium IX | An Iridium IX plug identified by NGK part and stock number. | Check Amazon availability |
| Bosch X5DC Copper With Nickel | Bosch lists X5DC in its copper-with-nickel range. | Check Amazon availability |
| Champion 71 RC12YC | A conventional Champion plug sold under stock number 71. | Check Amazon availability |
| Champion 592 RJ12C | A conventional plug for approved small-engine applications. | Check Amazon availability |
Check spark plug replacement specs before ordering
- Find the approved plug for the exact engine code, model and production year. Look for manufacturer-approved supersessions.
- Match heat range, thread diameter and reach, seat, terminal and prescribed gap. A physically similar plug can have a different specification.
- Check the service interval and electrode design. Choose the specified replacement for stock use. Confirm any change for a modified engine with the engine builder.
DENSO PK20TT Platinum TT
PK20TT, stock number 4504
Limit: Check the exact engine application and approved gap. Platinum construction does not establish compatibility.
Bosch ZGR6STE2 Copper With Nickel
ZGR6STE2, copper with nickel
Bosch ZGR6STE2 product specification.
Limit: Match the exact engine, seat, reach and torque before use.
NGK LFR6AIX-11 Iridium IX
LFR6AIX-11, stock 6619
NGK part-to-stock-number chart.
Limit: Check the vehicle application and gap instructions. Avoid forcing the fine-wire center electrode.
Bosch X5DC Copper With Nickel
X5DC conventional plug
Limit: Use the equipment or engine application guide. Confirm the package and any approved supersession.
Champion 71 RC12YC
RC12YC, stock 71
Champion RC12YC exact product listing.
Limit: Check the engine or equipment model. The broad vehicle words in a marketplace title are not a fitment guide.
Champion 592 RJ12C
RJ12C, stock 592
Champion RJ12C small-engine listing.
Limit: Use the equipment maker’s plug, gap and torque requirements. Check whether a different part is specified for your engine revision.
Use the specified gap and torque
Follow the service instructions for a cooled engine, clean plug wells, the approved gap check and tightening torque. Check the manufacturer’s guidance on fine-wire plugs and thread lubricants. NGK spark plug installation guidance.
Related guides
Recheck the exact listing
Confirm the selected model, seller, included items and current return terms before buying.
DENSO PK20TT Platinum TT
Check Amazon availability
Bosch ZGR6STE2 Copper With Nickel
Check Amazon availability
NGK LFR6AIX-11 Iridium IX
Check Amazon availability
Bosch X5DC Copper With Nickel
Check Amazon availability
Champion 71 RC12YC
Check Amazon availability
Champion 592 RJ12C
Check Amazon availability
Frequently asked questions
Can I choose spark plugs by electrode material alone?
Use the exact engine application first. Heat range, reach, seat, terminal and gap must match the engine’s requirements.
Do all iridium plugs fit the same engines?
Check the exact part number in the manufacturer’s catalog. Iridium refers to an electrode material and does not determine fit.
Should I adjust the gap on a fine-wire plug?
Check the vehicle and plug maker’s instructions for the exact plug. Use the specified method and avoid pressure on the fine center electrode.
What torque should I use for a spark plug?
Use the engine and plug maker’s specification for the exact thread and seat. Follow their instructions for thread condition and any lubricant.
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