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Raptor runs hot and then dies

11K views 7 replies 4 participants last post by  ct32413 
#1 ·
2004 with Yoshimura slipon, K & N filter w/no lid airbox, jetted but I don't know what size needles.

Heres my problem. The bikes runs great at sea level. I went riding in the hills 4000/5000' elevation and it ran horrible. Sputtering, backfiring, flooded basically rich. When I got it back home (322') it ran ok but I could feel heat pouring off right side of the engine like I never have before.

I took it to a shop and they replaced the "thermo switch" and I replaced the radiator fan. I can feel coolant surge in the hoses when I rev the engine so I am assuming that the water pump is working. I have never seen or heard the radiator fan old or new kick on.

When I start the bike up it runs/idles fine for about 3 to 5 minutes and then dies. I can feel heat pouring off of it (still) and I can not get it started unless I choke it. Once the bike has cooled off it will start up fine with no choke and then heats up and dies.

Before I send it off to another shop for some more trouble $$$ shooting, any ideas on things I can check on with my limited mechanical abilities. I have tried searching for similar problems but haven't seemed to find any posted. I have been impressed with the knowledge in this forum and eagerly await any assistance offered.
 
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#2 ·
Does it start idling very fast just before it dies?
 
#3 ·
Is heat coming from exhaust or engine case? You can divide the two. Super hot exhaust is fuel mixture and hot engine case is overload on the cooling system. The cooling system trades heat gathered up by the oiling system and exchanges it in the radiator. Check the oiling system to make sure you have good pressure. You probably do but a way to check (kinda messy) is to slightly loosen the oil line that starts just to the right of the oil filter and terminates at the top of the head. Don't completely disconnect. Just enough to verify good pressure. Just FYI I don't run with a cooling fan at all.
 
#5 ·
Varnish may have choked up the idle jet. I'm not exactly sure how the choke works on the raptor. Oregon uses california gas which absolutely positively sucks *ss. I run my carbuerators dry after every outing so that nothing is left in the bowl. Some senior posters need to chime in here and kick up some ideas. :help: 3 to 5 minutes is about how long it takes to empty the fuel bowls at idle with the fuel turned off. Is the fuel somehow restricted to the carbuerators? That would explain how it runs for that amount of time then cools off (or refills the bowls) and will restart, only to repeat the process.
 
#6 ·
yea.. start there...

pull the carbs.. and clean the crap outa them

set the float levels PERFECTLY (see the tech section stickied above)

and while in there check the valves, tight intake valves get even tighter when hot

once you know the carbs are clean, adjusted and perfect, and your valves are good, report back and we will go further if needed
 
#7 ·
Can't think of anything for the heat issue... but as to the dying due to lean (from your description)...

Check the gas cap for a restriction in it's vent and the vent tube itself. Had the same problem with a Yamaha bike. The gas cap vent hose was kinked down where you couldn't see it. Bike would run for a few minutes until vacuum would build up in the tank (cuz the cap vent line was plugged) and would stop fuel flow. After a few minutes of no running, enough air would enter the tank to allow fuel into the carb again... and the process repeated over and over. When we found the kink in the cap vent hose it was one of those DUHHHH moments. I always check the hose after gassing up now.

May not be your problem, but it's a simple check. Pull your gas cap and see if the problem goes away.


Good Luck!
 
#8 ·
Well valve gapping is pretty important in keeping your bike running well. The intake was loose and exhaust was too tight. I bought the bike used and don't know the history of it. I had put cose to 20 hours on it and had never checked it. Everything seems to be running normal now so I guess thanks for any suggestions offered.
 
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