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Need help with 450 04mod performance problem

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I have a wr450f 04 model and need some help. It's like ignition cut on a given rpm. Bike is completely stock with only 500km on it. This problem has not been there earlier but now it's there all the time. Happens all the way between 70-80 km/h in 4gear and between 85-95 in fifth. Dont know if it is ignition problem or carb. Is it possible that it can be the pilot air?? Thanksful for any idea to solve this problem.

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My lokal dealer dont know a damed shit about this bike.... My bike is the first one of this kind he have sold...

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I have a wr450f 04 model and need some help. It's like ignition cut on a given rpm. Bike is completely stock with only 500km on it. This problem has not been there earlier but now it's there all the time. Happens all the way between 70-80 km/h in 4gear and between 85-95 in fifth. Dont know if it is ignition problem or carb. Is it possible that it can be the pilot air?? Thanksful for any idea to solve this problem.

Normal, you are knocking on your rev limiters door!

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Bike is completely stock with only 500km on it.

You haven't put in the YZ throttle stop? You're missing a lot if you haven't done this.

Jerry

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Normal, you are knocking on your rev limiters door!

No way! Maybe at 12-52 gearing.

Try doing a search for TPS and see if your symptoms match the problem others are having. Like a surge at steady throttle openings?

EDIT: You guys are thinking M/PH, he does say KM/H though.

Oh and a Euro bike probably doesn't have the longer throttle stop.

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Gearing on bike is 14/50 and there is nothing like a throttle stopper on this bike. And like Luke n said the problem is not that I'm knocking on any rev limiter door... 100mph = aprox 160kmh anyway thanks for answering! I'l search for TPS problems and see if that can help me solving the problem.

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Now I have changed the needle possision (richer), also done the air cut valve mod and uplugged wires to TPS but the problem is still there.... If was a little bit better when unplugging the tps.

Anyone who have a idea what this could be

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Post all your jetting specs, mj, maj, pj, paj, needle, clip position, etc.

It could be as easy as a main jet change, but I'm not sure how the stock jetting is in Norway, and you said it's a new problem. However, because you said it's a 4th and 5th gear issue (I'm assuming higher throttle position) I would think main jet or needle. Maybe your mj is clogged.

It's probably not a pilot circuit issue, but FYI, the paj controls vacuum at the pj.

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It's a common problem with the ignition mine does it every now and then spray some WD-40 down it or by-pass it and the problem goes away :D

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Disconnect your TPS at the carb. If it goes away then you have experienced the standard design flaw in the CDI feedback loop with the TPS. If that does not solve the problem you have to rejet to eliminate the cutting out. :D

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carburator ID mark 5TJ2 10. Jetting specs: M.J160, P.J48, P.A.J80, P.S1 1/2

nidle clip possision 4 (from top) standard 04 nedle. Bike is completely stock (no modification on airfilter or exhaust ) I'v reversed the air cut valve mod.

Can anybody tell me what the TPS realy is good for? Why is it on this bike if you can unplugg the wires and engine still runs and performance good??

I'v also measured the TPS as manual tells me to do and I find it ok due to those values mentioned...

My lokal dealer still dont know anything about this bike and the guy who work as bike tech (yamaha norway) and probably could have solved this problem is on holyday.....

I think I will have a nervous breakdown soon....

Riding condition is from sea level and up to 1000ft and temprature now is 15 deg celcius.

Also, is it any risk to drive bike with TPS unplugged? (engine, cdi og other electrical damage)?

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Not sure if this will fix it, but try a 165 mj or just make sure the 160 is clean. It's real easy, no need to remove the carb. Just drain the bowl, remove the plug and get the mj out with a 6mm socket. Can't comment on the TPS, although I've had it on and off (currently on).

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Thank you for answering! I'v spoke with a "yamaha guru" and when I told him the symtoms of failure and that the problem seemed to be gone when unplugging the TPS he told me that this was a TPS failure and that he had experienced this several times earlyer. I also asked him about unplugging the TPS and the only thing that happens is that cdi unit "read" throttle possision fully open and adjust ignition from that. He also said that I may notice a drop in throttle response in low and midrange throttle area...

By the way he also told me that it was almoust impossible to measure the tps like manual said because it can seems ok while engine not running but when engine running you have voltage input and also the vibrations.

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