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YFZ450 problems??

Old Mar 1, 2004 | 03:00 PM
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Default YFZ450 problems??

Hey all,

I have a yfz450 with the White Brother's E-Series Titanium Race pipe. Had the dynojet stage 2 jetting in it and it was popping and backfiring. Took it to the shop and the Throttle Position Sensor was bad and was shorting out the CDI Unit. They replaced both TPS and CDI and the bike is fast no doubt, but it still pops on deceleration and it popped a couple of times on acceleration (around high third gear).

Took it back to service, they said it was running way to lean, yanked the Dynojet kit and installed the White Brother's jet kit that came with the pipe (which is a 168 main and a larger pilot jet...why they change the pilot I don't know). Took it out to Glamis last weekend and I lost almost a gear in speed....totally dogged it out -- still fast -- still beat 450r and raptor, but not nearly as fast.

I am going to go back to the Dynojet kit and maybe go up one size on the main and see how it does....just wondering if anybody has any advice for jetting the Dynojet kit for stage 2. I called Dynojet and they just recently (in the last week) revised their after-market needle that comes with the kit for my bike, so I will probably go with their specs with the new needle to start....unless someone has better advice.

If you are going to offer jet specs - please make sure they are dynojet - they do some wierd things. Stock main I think was 152 or 158 (can't recall) and Dynojet's stage 2 main is 142 with a thinner needle and a main jet extension. Odd.

Anyway - also wondering from anyone with an e-series pipe (not even necessarily on a 450) if you have popping on deceleration....not a lot, but some popping. This is my first four-stroke - sold my Banshee and went this route, so everything sounds a little different [img]i/expressions/face-icon-small-smile.gif[/img]

Thanks!
 
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