yamahabansheeboy

my 2002 400ex just wont start but wants to

33 posts in this topic

i just got a 2002 400ex and..................

when i try to start it, it tries to start and stops tries to start and stops tries to start and stops over and over, like it has the hiccups, but wont start and run. the carb is clean and it's getting gas to the engine, the spark plug is sparking a blue spark when i hold the plug to the frame. ive put a new timing chain and stock cam shaft in it, and set the timing, and it has a new piston. anybody know the problem??

:aargh::aargh::aargh::aargh::aargh::aargh::aargh:

thanks

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there are 3 basic principles for diognostic

spark/fue/compression

you have ther first 2 now check compression and leak down

that will tell you if the piston is too small for cylinder/need boring

or valve train has a problem

the reading can also signify timing issues

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THANKS to EVERYONE for the help its in the local shops hands now i dont have a filler gauge to adjust the valves and i did not want to send a valve through the piston from bad timing. the shop can get me running right.

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THANKS to EVERYONE for the help its in the local shops hands now i dont have a filler gauge to adjust the valves and i did not want to send a valve through the piston from bad timing. the shop can get me running right.

Cool, let us know how it goes and what the issue was.

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Got $5 that says it's a problem with the compression release. Would have suggested that earlier, but I did not catch this thread until the day that Bansheeboy posted that he had already sent it to the shop.

Edited by DirtDemon

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The compression release is on the cam, and it sounds like it isn't working. It should bump a valve open as the starter turns the engine over to release some of the compression in the cylinder. If it isn't working, the starter will have a hard time turning the motor over and it will make bad noises when it is trying to start.

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will that cause it to try to start and stop tries to start and stops tries to start and stops over and over, like it has the hiccups but just wont start. the starter seems to be turning the engine over fine but thats not to sey it is.

Edited by yamahabansheeboy

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That sounds very similar to what my friends 450R was doing when he broke his decompression pin in his cam. It would turn over, but it would kind of "hiccup" and sounded like it was kicking back and stopped. It did not sound pretty when he tried to start it, so we just started taking it apart and found the broken pin. Since we were already in there, he ordered the new decompression cam and pin along with a stage 1 Hotcam. Is your machine still in the shop? If so, any word from them? Are you completely sure you had the timing chain on right?, the marks on the cam sprocket line up and you are sure the crank is at TDC when you lined them up?

Edited by DirtDemon
oops

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yea im 100% sure the timing is correct, the shop told me they had checked it and it was not the problem it was instilled correctly. the bad thing is, is the people at the shop are confused on as of why it wont start and if anybody should know there stuff it's them LOL.

but thanks DD for the help

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If it isn't the decompression mechanism, it sounds like you aren't getting spark at the right time. Ask them if they have checked the flywheel key.

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well i called the shop yesterday and they said it's a stuck exhaust valve and today they sey it's not, whatever the problem is it's sure whipping there ass! maybe some time this year ill get it back!?!?!?!?!?

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Take it back and take it somewhere else, do not give them a dime, because they are incompetent. They should have this fixed by now. The only thing that makes any sense to me is the decompression mechanism. If it isn't working at all, it will not release compression and the motor will have a hard time turning over. More importantly, if it doesn't stop working like it is supposed to when the motor starts, it would be just like a stuck valve. Since they were suspecting a stuck valve, maybe they need to take a look at the decompression mechanisme again.

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i stopped by today at there shop and there saying the cam shaft is bad, i remembered you saying the compression release mechanism on the cam shaft is not working, so the -BRAIN DEAD- mechanics there to check it out. and it's pretty damn bad it's been 3 full weeks and there steal dicking around with it!

THANKS AGAIN D.D

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Yes, 3 weeeks is ridiculous, they are supposed to be professionals. It should have been fairly obvious if the cam was the problem. Make sure they don't sell you more than you need. If the cam is bad, then replace just the cam, I would suggest upgrading to a stage 1 hotcam if it needs to be replaced. If it is just part of the decomression mechansism that is not working properly, don't let them try and sell you a whole camshaft assembly with it. It may just be the spring for the decompression cam that sits on the actual camshaft. Ask to see the defective part, or parts before you authorize these morons to do anything. I still think it may be in your best interest to take it elsewhere, if it took them this long to find the problem, do you trust them to be able to fix it properly? What ever you do, I hope you get your quad back and running soon.

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Yes, 3 weeeks is ridiculous, they are supposed to be professionals. It should have been fairly obvious if the cam was the problem. Make sure they don't sell you more than you need. If the cam is bad, then replace just the cam, I would suggest upgrading to a stage 1 hotcam if it needs to be replaced. If it is just part of the decomression mechansism that is not working properly, don't let them try and sell you a whole camshaft assembly with it. It may just be the spring for the decompression cam that sits on the actual camshaft. Ask to see the defective part, or parts before you authorize these morons to do anything. I still think it may be in your best interest to take it elsewhere, if it took them this long to find the problem, do you trust them to be able to fix it properly? What ever you do, I hope you get your quad back and running soon.

thanks again D.D

it's sad there a business and they do shity work like this! they always call and ask before they do anything to fix it so ill know whats going on, and im going to go there monday and check out what there saying and go from there.

the place is........... Greenfield motor sports in Indiana, they have a website also.

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Good luck, and don't take any crap off them, you have put up with enough IMO. I will look forward to hearing how your Monday goes.

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Good luck, and don't take any crap off them, you have put up with enough IMO. I will look forward to hearing how your Monday goes.

thanks, im looking forward to it to.

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