YZ450f ***? pleasehelp

they di all that and then noticed the fuel screw??.......did they put the jetting back to where it was??.......you may need a new mechanic
I went to the same place when I read that.
I went to the same place when I read that.

well after they tore apart the carb for the second time, and it popped after that they prob figured they would look elswhere and focused on the headwork they did. Can't really say I blame them. I mean really this whole issue is prob caused by something stuipid that was missed when they originally did the top end. The bike ran flawlessly before all this work. I should have just let it burn oil and said screw it.

The point we were making was that there is no excuse for a professional to be able to "look into" a carb 3 times and fail to notice a loose of missing fuel screw. None.

understandable, but non of this helps me with my problem. At this point if I go to another shop I get the joy of paying more $ all over again. While if I stay with the shop that did the work, I won't have to pay a dime since they did and will warranty the work. And will continue to work the prob until correct. So a different mechanic at this point is out of the question. Back on topic I know its not the carb at this point, What else could they have messed up in the top end making the darn thing run rich?

Nothing but the carb can actually make it run rich, but cam timing can make it run poorly. There's some possibility that if they cracked the coil in all this messing around that it might be arcing or otherwise malfunctioning.

One thing to remember when troubleshooting something like this is that although when a problem comes up right after some work was done, logic suggests that it's related to the work done, it's not necessarily true, and at some point, you have to drop back and approach the machine as if you have never seen it, checking everything in a sensible systematic order. It might be something coincidental and unrelated.

ne thing to remember when troubleshooting something like this is that although when a problem comes up right after some work was done, logic suggests that it's related to the work done, it's not necessarily true, and at some point, you have to drop back and approach the machine as if you have never seen it, checking everything in a sensible systematic order. It might be something coincidental and unrelated.

:thumbsup::thumbsup::blah: Read my thread today on loose flywheel.

It happened at the same time the valves were adjusted.. so when things went bad, and cam timing was found to be off.. It was assumed , it was a mistake as part of the work being done today adjusting valves and installing cams..... not a loose flywheel installed months ago, that just today decided to slip on the crank, and screw up timing.

Once all possible checks were made on the cams..., we stepped back,, checked the flywheel and yup,,, it was off about 10 deg. So even when all marks were lined up...... timing was still off.

cool thanks for pointing me in another direction. I will have them start checking some of the above mentioned and see how it goes.

Finally got the damn thing running right. After another leak down test the engine was loosing pressure somewhere. They checked the valve clearances and everything was fine. So they tore it all down again, put in another set of gaskets and rings. Took it for a ride today and problem appears to be solved.

Did you see the engine disasembled? Piston condition and the cylinder bore? When head gaskets leak water into the cylinder it coats everything with a gummy carbon/antifreeze spooge. Your gummy cylinder may never develop a good ring seal. If you get alot of water in the chamber you can easly crack a piston, usualy in the thin section between the pin and bottom ring-land. Keep a close eye on your water level and pull your plug and look for moisture from steam in your chamber on your sparkplug after it cools.

This can get ugly when at high RPM your piston goes to pieces and takes other parts with it.

I didn't personally see the components, but I did ask the mechanic who is a bit of a friend. He said everything looked fine ( I have no reason to doubt him) But I will keep an eye on the coolant and plug for the next few rides.

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