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Discussion Starter #1
ok so this raptor in question is bone stock 02 660 it went in to have the valves adjusted cuz it was losing a little top end in each gear , after the valves were adjusted it would only run for a few min and at idle only,then die, now the carbs have been cleaned the valves rechecked the pb switch unplugged and the rev limiter grounded to check still no change.. good compression a set of carbs off another stock raptor were tried on it and same thing,cdi overheating? since it will only run for a bit then die..also no vaccum leaks found
 

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Master of the Electron
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IF this occurred immediately after 'it went in', I suggest it goes back for them to fix it!
 

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Discussion Starter #3
thats the problem its still there and they are scratching there heads...and its not my bike so im tryin to trouble shoot from a distance... but if they did what all they say they did my last guess would be the cdi....maybe should let em borrow the one off my 04 for a test
 

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+1. "it went in" where? What kind of dealer/machanc returns a bike that dosent run? Bring it back and demand for a "real" mechanic to fix it. If not, take it elseware for repairs. GET YOUR MONEY BACK!!!!!
 

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Discussion Starter #5
it wasnt returned and hasnt been yet, when my buddy went to see if it was ready so he could ride they said it isnt ready and what i described is why so it still hasnt been returned and they still cant figure it out other than they wanna try a new cdi on it
 

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Master of the Electron
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The ONLY thing they did was adjust the valves? If so, I'd guess they adjusted them at TDC exhaust instead of TDC compression... and they're so loose that as the head warms up and moves the rockers away from the valve stems, the clearance is so huge it won't run.

Have them check clearance again, and have them EXPLAIN to you how they determine the difference between TDC compression stroke (where they should adjust) and TDC exhaust stroke (where, if adjusted, clearance will be way too large).

Else, if they removed the tank, it could be a fuel delivery problem - have them check to see if (with the fuel hose disconnected from the carb) that fuel flows continuously and for quite a while out of the hose into a container... if not, it could be either the petcock, filter screen or a plugged cap vent.

Also, just to check if this is sheer coincidence, have they determined whether it dies due to loss of fuel or to loss of spark? To see if it's fuel, spray starting fluid into the snorkel right as it starts to die - if it tries to keep running it's fuel starved. To check if spark, put an inline spark tester (you can get em at Harbor Freight for a few bucks) and run the bike, watching the spark in the tester... does it die because spark goes away? If so, unplug the rectifier regulator and try it again... no more death? It's a shorted stator.

That's all I can think of for the moment.
 

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The ONLY thing they did was adjust the valves? If so, I'd guess they adjusted them at TDC exhaust instead of TDC compression... and they're so loose that as the head warms up and moves the rockers away from the valve stems, the clearance is so huge it won't run.

Have them check clearance again, and have them EXPLAIN to you how they determine the difference between TDC compression stroke (where they should adjust) and TDC exhaust stroke (where, if adjusted, clearance will be way too large).

Else, if they removed the tank, it could be a fuel delivery problem - have them check to see if (with the fuel hose disconnected from the carb) that fuel flows continuously and for quite a while out of the hose into a container... if not, it could be either the petcock, filter screen or a plugged cap vent.

Also, just to check if this is sheer coincidence, have they determined whether it dies due to loss of fuel or to loss of spark? To see if it's fuel, spray starting fluid into the snorkel right as it starts to die - if it tries to keep running it's fuel starved. To check if spark, put an inline spark tester (you can get em at Harbor Freight for a few bucks) and run the bike, watching the spark in the tester... does it die because spark goes away? If so, unplug the rectifier regulator and try it again... no more death? It's a shorted stator.

That's all I can think of for the moment.
+1. I hope this isnt a Yamaha dealer mechanic you are teaching. Hope QM input helps. The shorted stator problem can confound the best. Good luck.
 

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Discussion Starter #10
i am unable to check any of it my self cuz its at the dealer other wise i would have checked spark and fuel right off... just like any engine spark fuel compression and so forth, im going on the osumption that they already checked these things and that would lead me to possible cdi over heat as i have seen 1 or 2 lose or have intermintent spark cuz of it, but intell they figure it out or give up im just rounding up few ideas ,im a auto mechanic and just tinker with atvs/bikes just cuz its funner than autos
 

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Master of the Electron
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Honestly, out of perhaps 10,000+ issues I've seen here on the forum, I can't recall more than two that were a funtion of the CDI preventing the engine from running... There have been other CDI issues, but they have not prevented the engine from running - they can prevent the starter from turning over, etc.

If there is spark, it is almost 100% NOT the CDI. Unless one looks at spark (using a spark tester) WHILE the failure is occuring, it's going to be a shotgun approach - replace components until it starts working again (if ever). This is what most service techs do, simply because they don't understand how to troubleshoot. THis is NOT the way we do it, here in the forum.

If this failure IS just a coincidende AND due to loss of spark, and a function of heating up, it is much more likely the stator - a common failure point in which thermal expansion HAS caused loss of spark. Again, I suggest unplugging the rectifier/regulator, just to eliminate the most common stator failure as a suspect.

BTW, if they went to the trouble to try a pair of carbs off another Raptor, why haven't they tried the CDI of that other bike too? As long as they're both 02+ bikes, they are perfectly compatible and it is a 5 minute test. I'd like to place a bet on the outcome... but the goal is just to prove that the failure is not the CDI... if it is, I stand corrected, but at least the problem has been solved.
 

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Discussion Starter #12
i still havnt heard anymore about his bike.... might stop by there after work and see if they mind if i run some tests....gotta love when you try and maintain your bike somthing has to go wrong
 

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Master of the Electron
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So, you going to find a new service facility now?
 

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Master of the Electron
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