Struggling with the jetting on my '02 426

In the past 2000 kms, I have changed the plug 6-8 times because it is carbon fouled... I have gone from a 165s Main down to a 155, Had the needle (OBDQR) on the second from the top all the way through to the second from the bottom. I have done the BK mod as well as timed the squirt as per the manual!!! It is a "Canadian Model" with a stock Stainless Pipe and can (Cannot remove the baffle in the end as it is a welded in piece), it has the airbox lid on, but snorkel removed. It runs good for a couple of hundred Kms, then it starts to buck and fart until it gets warmed up (to get it warmed up, I have to hold it Pinned down the road... not too good riding in town) It has a BD Quick release DS kit

I am running a

OBDQR on #3 position

Main 162 (Now)

Main Air Jet 200

Pilot Air Jet 75

Starter Jet 65

Pilot Jet 45

Today, I checked the plug and it was white in the middle and "black as the ace of spades" on the outside edge. I checked the float level and it appeared to be too high, I set it to the specs in the manual. I raised the needle to the #4 position and put a new plug in it... ANY IDEAS...??? WILL A JD JET KIT HELP ME FIX MY SPUTTERING PIG...?????

PLEASE HELP?!?!? :thumbsup:

Here is a dumb question for you, have you checked the air filter? How about valve clearances? Symptoms seem backward for valves, but you never know. What plug are you running? Are you sure it is the right one? I am running a CR8EIX in my 02 and have only fouled 1 plug ever. Just a few suggestions, hope this helps.


Filter was just cleaned (using Bel-Ray) filter oil... Haven't checked valves- seems too intermittent.... runs fine for a couple of weeks then starts the sputtering.... new plug and a couple of carb adjustments - runs fine - think it's fixed... then it starts sputtering... After the last adjustments, I haven't had time to try it... I'm going to see STAIND in concert tonight with my wife... getting up early tomorrow and heading to the single tracks of Michigan... I'll post back tomorrow Night... Thanks for your help


My 426 would foul plugs too, it turned out the center intake valve was too tight. Once the valve was reshimmed all the problems went away.

Last year mine did the sputtering , plug fouling game and after I installed a Vortex CDI ignition the problems were gone. The Yamaha CDI is a weak spot on that bike. My .02 -- WR Dave

Thanks... I'll look into the CDI, as well as the valves... My friend is a mechanic at the local Yammie Stealership and said he'd do it at home...

I now have a new problem... Hit a large stump while single tracking in Michigan and now appear to have a bent left fork :thumbsup::applause: ... Assume that it is the outer tube that is bent just below the bottom clamp... Any ideas?? or places to get cheaper replacement parts... A new complete fork runs almost $700 US from most websites that i could find, and an outer tube is around $300-$350... As for the adjustments I made to the Carbie... I never really got much seat time to find out (4-5 miles) before my ride came crashing down!!!!


Try E-bay, I think I have seen whole fork sets go for around $300. Are you sure it is bent and not just twisted in the clamps? Just a suggestion, hope this helps.


Yesterday, I loosened the clamps and gave 'er a good hard shake on the bars with the wheel between my legs and everything seemed to straighten out. I tightened it back up and took it down the road.... it went where the bars were pointing... So I guess I was lucky!!!

Thanks for your help...


That is actually a common problem, and you pretty much did the proper fix for it. As long as they are straight you should be good to go. Glad you got it.


Try disconnecting the neutral wire ( I think it was sky blue on Canadian model) That allows for a stronger spark when bike is in neutral. I went from fowling plugs three times a summer to zero times.

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