THEMOOSE
where did you get a factory service manual
i like to get stuff like that before i buy a new quad

 

Raptorguy,
Get a service manual. $50.00 or so. The valve adjustments are a piece of cake. Any ATV or motorcycle shop should be able to get you one. Most any online store will be able to get you one. When I bought my Alba pipe kit they had one in stock. I took it home with me that day. Don't pay $100.00+ to have a dealer do your valves. Even if thats not your problem you need to do your valves once in a while.

 

It sounds like an ignition problem, and most likely the coil. Look at the coil very closly for cracks, and if you see one replace it. It could also be an internal problem with the coil. If the coil gets hot it will start to break down and sooner or later it will quit. From what you described, the times for the dying and then to be able to resart are pointing coil problems. Check your resistance cold, both primary and high tension then ride it for 10 minutes or so and check them again. If there are any noticable changes, replace the coil. You can do the same thing with the trigger and wiring. Also check for moisture. It is possible that moisture is is gathering in places it shouldnt after things get warm. This will be especially true if the machine is kept in a garage overnight and it is humid. Once the engine starts, and things warm up, the moisture will try to evaporate. But if it is trapped in a connection or similar place then it could cause a short.

Good luck, intermittant wiring problems can be difficult at best and nearly impossible otherwise. Dont give up, and dont let someone who doesnt know what they are doing work on your wiring. Lifetime of headaches to thoise why try but cant.
Ron

 

blastermaster, I got my manual from the dealer, I think it was around $53 & $15 for the 02 supplement.

 

Be sure to check for vapor lock too. Maybe the breather for the gas tank is kinked or clogged.

 

Alright guys, I went all through my Yamaha service manual last night and could not find anything about "adjusting" the valves. I had everything else, lapping, removal, checking runout. It would appear to me that to adjust the valves you are going to use the adjustments off the rocker arms. If that's the case,are there clearance specs? I know when I do an auto motor its get the rocker on the tip of the valve, but not too tight that the rocker can't flex sideways ever so slightly. I've got the day off so I'm going to be digging into all the above mentioned suggestions. Thanks for all the info.

 

raptorguy, you must've been looking at the owners manual that came with your quad, you need a Factory service manual it has all the specs in it. You can get one from your Yamaha dealer (about $53 & 15 for the 02 update) It's not the greatest manual for shadetree mechanics (it's kind of vauge) but it's all we got for now.

Valve clearamce is intake: 0.10mm~0.15mm (0.0039in~0.0059in)
Exaust valves: 0.15mm~0.20mm (0.0059in~0.0079in)

 

it sounds to me like you have a fuel blockage somewhere.either in the fuel line or the carburetor.or your vent hose on your gas cap is plugged or kinked.i've seen it happen a million times.sometimes the most simple thing in the world can be the hardest to diagnose.

 

TheMoose,
Thanks for the info. I have the dealer manual, 60 bones at my bargain dealer. I was looking at the section in the back about valve removal and inspection. I found your numbers up front in the maintenance section thanks though.
I don't think its a fuel problem. I checked the full lines, they aren't kinked or and seem to flow fine. Plus the problem only occurs after a period of riding. Unless it was vapor locking, a fuel problem would bother immediately. As to who mentioned the coil, it looks fine upon inspection, but my meter is at work so I can't measure resistance today. Spark plug wire is fine. Gonna pull the carbs and just give them a once over. We'll see what happens.

 

Raptor valve Adj.
Here is a link I used to adjust the valves on my Raptor it's pretty easy. Even if it's not the cause of your problem, if you haven't adjusted them yet I would do it anyways.The exhaust vales on mine were right on , but the intakes were way tight. Hope this helps.