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2001 Raptor 660r
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5 Posts
Discussion Starter #1
Hey all, asked this in a FB group but no one seems to help, probably as confused as I am.

My problem is it does not start when it's hot coming out of winter. Starts amazing when cold. I have re-adjusted the valves as an attempt which did nothing except make it much quieter, I can actually hear my tires on the road now! I adjusted at wrong TDC 馃槳 spec was at 0.25mm all around lol. Someone suggested that was the problem and while it needed attention it unfortunately wasn't. Im positive it's a carb thing because the whole engine has 4hrs on it since total rebuild. I'm good at jetting but this is killing me. Once it cools down and starts it pops and some black smoke. So I leaned the idle screws till they went all the way in practically and nothing. Back to recommended adjustment. Here's where my brain crashes... Spark plug is dry when trying to hot start and when idling using the choke causes it to Rev up (maybe lean) but when trying to start it while hot choke does nothing and smell fuel (maybe rich). Another thing to note, if I hold the throttle full with no choke it makes this awful clunk typically 3 seconds in like it is pre igniting. The clunk sounds seems to be kickback from the crank to the starter. This only happens once. Now this is a performance build and I will have specs below, considering this, I had the edges of head rounded to prevent preignition. Lastly, used to run 112F now its at 144F because all the power I'm guessing and just maybe the missing heat shield below gas tank is causing vapor lock.

I don't have an exact question but I'm sure you know what I'm asking. While I could probably figure this out with a lot of frustration I only get to see her on the weekends and can't sleep at night not knowing the issue haha. My prized possession.

Stage 3 Hot Cam
Kibblewhite Valve Springs and Valves
102mm CP 11:1 piston
+4 Hot Rods Crank
719cc (I think)
HMF Comp
Stock headers
FMF Stage 1 kit, tuned before build, adjusted needle to compensate runs perfect other than above issue
 

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Sounds carb related to me, the new build wants more fuel. Jet it up
 

Registered
2001 Raptor 660r
Joined
5 Posts
Discussion Starter #3
Sounds carb related to me, the new build wants more fuel. Jet it up
Interesting... heard to do the exact opposite when building bigger. But hey, why not try what I haven't done! Thanks!
 

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in general you stay the same or drop down a jet size when you build a big bore but that is assuming you were correct before you started. do you have the stock carbs or is it a 1 carb conversion. i know the plug is new but try another. what coolant are you running? i agree with digger for now it sounds lean because of the higher running temps. i dont know the compression ratio for a stock 660 but i assume 11/1 is higher you might need to run 20 or 25 percent race gas to keep it from detonating and help with the hot starts. if you have a bore cam look at the top of the piston for signs of detonation. you talk about wet and dry plug but what color is it.
 
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