Working on my buddies 02 raptor 660. It died when he was riding, sometimes he can get it to start but it dies when you give it gas then won't start again.
It has spark, new battery, New air filter, he said compression is good, would this be a fuel issue or maybe electrical? He is dropping it off tomorrow so I will verify then whether or not it is getting fuel at the carb. Just trying to get a head start on other things to look into. Thanks for any help

 

Intermittent faults are bad to find. Fit a new plug, and check the voltage at the battery with the engine running, should be 13v to 14.5v and move about a bit with increasing revs. It probably is fuel, check the cap vent works, but most likely dirt or water in the carb. If you can catch it with the fault "on" you can check for a spark, otherwise, intermittent electricals are the worst to find.

 

A few suggestions. First, of course, check the gas. Anything with the gas not getting around could cause this. Anything along the carburetor or fuel line. Also, I actually had a fairly similar problem with my Raptor 350. After a ton of time and work, I found out it was simply one of the air valves on the top of the carburetor was loose.

Good luck

 

Ok so he finally dropped the raptor off tonight while i was at work. So I charged the battery, new battery. Tried cranking it and it will crank all day and won't start. I pulled the plug and it has no spark. Well it has intermittent spark I should say. If I crank it, it will spark maybe once or twice every few times I try to crank it for a few seconds. I checked plug wire and no damage, wiggled it around while cranking but no change. Disconnected rectifier/regulator and I have spark when it's disconnected.
SO that points me to a bad stator, but why would I have intermittent spark? He said he can sometimes get it to start but it would die when he gave it throttle then wouldn't start back up. ?? Anything i can check or test before I determine its the stator?

 

mainly only get a faint quick spark when i release the starter button, but not everytime.

 

If the bike sparks OK with the regulator disconnected, most likely it is the regulator at fault. Stators can be checked, not always 100%, but if you get the same resistance on all three stator wires, and they are not earthed, the stator is probably OK, so get a new regulator.

 

All the searches I've done said that if you have good spark and the bike starts and runs with the regulator unplugged then the stator is bad. So it might just be the the regulator? How exactly do i do the stator test? Fixing for a friend so I really don't want to throw parts at it ya know. I appreciate the help though. I'm still learning the electrical part

 

Also when I just unplugged the rectifier, I started it up. Idles and takes throttle like it should. As soon as I plug the rectifier back in, it dies..??

 

Most bikes will run quite happily with a dead stator. One of my friends ran his Vinson for a couple of months through lambing time with a dead stator, just charging a spare battery up and swapping them when the bike got bad to start. We fitted a new stator when the pressure of running the bike 8hrs a day was off. Honda 450FMs will usually not run if the regulator fails. So do the tests on the stator. As it runs with the regulator disconnected you could also check if the stator wires produce voltage when running (AC) but this is quite high, could be well over 100v, so be careful not to get a shock.

 

Dude, how did that bike run so long without a stator