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WR372

03 WR450 Jetting Q's

8 posts in this topic

I posted this in the Jetting forum as well

think I am getting a pretty good feel on this jetting stuff. However, I am still a bit frustrated getting it dialed in. The setup:

04 WR450

500-1000 ft. elev

165 main

blue 5 from bottom

45 pilot

airbox lid removed

end cap removed

60-65 deg.

I think the bike runs pretty well now, but it still has a studder at 1/8 to 1/4ish while cruising steady throttle in 4th or 5th gear. After searching, this might be the TPS. It studdered real bad with the clip at the 4th from the bottom, and was almost the same at the 5th and 6th.

My other problem is the fuel screw. At all of my testing the best position for the f.s. was all the way in. It is a storm cycle f.s. I tried the 48 and the 45 and there was no change in the studder, or the fact that the f.s had to be all the way in to run well. Could I have to go to a 40 pilot? Is the f.s bad? Am I way off on my numbers here? Any thoughts and suggestions?

Thanks

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Put the red needle in at 4 from the top ( Clip positions on needles are always referred to from the top on jetting posts):cheers:

The blue needle is to rich for under modified air box / pipe combinations and your described conditions.

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Put the red needle in at 4 from the top ( Clip positions on needles are always referred to from the top on jetting posts):cheers:

The blue needle is to rich for under modified air box / pipe combinations and your described conditions.

^He's the man and I will add that the stuttering condition is from using the blue needle. It is way rich. Put the red one in like Indy says and the stuttering will disappear.

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Well I changed to the Red #4, I am running the 165 Main, and from recommendation in the jetting forum I am running a 40 PJ. The fuel screw still is all the way in with the bike idleing just fine. I tore the carb down to clean it out and make sure nothing is sticking. Now there is a very noticable stumble from idle to 1/2 throttle. When I give it a good wrap (not a very fast one) it stumbles or dies. It did it to an extent before, but never this bad.

So what is the problem? Why am I not getting any response from my fuel screw? and did the smaller PJ cause the stumble off idle?

Thanks

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40 pilot seems low for any WR450. Do you mean a #40 leak jet ??? that would be a good choice. I would put back the stocker (45) or even drop in a 48 and evaluate again.:cheers:

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the 40PJ was recommended by burned, I have had the 45 and 48 in and cannot get it to adjust on the fuel screw though. Thats why I went to the 40PJ. I havent changed the leak yet, because my dealer doesnt carry them and I havent looked for another source.

So what else would cause my fuel screw to be unresponsive?

Thanks

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Disconnect your TPS and your problems will be over. Trust me, I went through the same frustration. Once disconnected, follow the rest of the standard jetting advise and your bike will run smooth and strong. Sorry if I upset any of the pro tps dudes, but my '04 doesn't like it's TPS. Don't ask me why.

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I have a feeling the TPS will help with the 4th/5th gear cruising studder, but I am not sure it has much effect on the low end off idle studder.

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