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Scoredaddy

Jetting Q?

6 posts in this topic

I bought a 01 YZ426F a month ago and I'm going through plugs left and right. The power is there all the way through but what's next? Change jets or move needle?

I'm also running a NGK CR9E plug will it make a difference using a CR8E?

Understand that I'm not very mechanically inclined but that will more than likely change soon!

Thanks, Scoredaddy

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Scoredaddy, the only way I could get mine under control was to follow BK's advice and start running a higher octane fuel (I mix pump 92 octane with VP 108 and run 100 octane fuel) and do his carb mod which leans out the accel pump squirt. Fixed mine and it runs awesome!

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The stock plug is a CR8E, I do not remember if 8 or 9 is hotter. If the 8 is hotter then you will want to change.

There is a long list of stuff to check but first, are the plugs fouling while you are riding, or only when you give it the first cold start of the day (or only during starts in general)?

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The 9 is colder, NGK gets hotter on LOWER numbers.

I know the manual lists CR8E OR CR9E but most guys I think run the 8, and that is what comes in them from the factory (all the ones I’ve seen, anyway).

My advise would be to try the 8 and see what happens.

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BK is Tim Ferry's Mechanic and he visits this fourm now and then. Follow his carb mod suggestion and I believe you will like the results.

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