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Discussion Starter · #1 ·
To all,

I am helping a friend out. He brought me an 03/660 Raptor that was running poorly. I did not start the bike, I stripped the quad down and started looking for obvious problems. I took the carbs off and disassembled them. I cleaned everything and replaced all seals, installed a dynojet kit, new needle and seats, and checked the floats (no holes). I put it all back together with some new gas and it started right up. When i mash the throttle wide open all it does is sputter. It almost sounds like its getting enough fuel just to pop but then nothing. I took the carbs back off, re-cleaned them, blew them out with HP air and reassembled and it's still doing the same. This quad has no mods with the exception of the new HI flow intake and filters I installed for him. I'm not a yamaha man (Honda and KTM) and I cannot for the life of me figure this out. The setting on the carb were set to Jetkit recommendations based on 0-3000 ft riding. Any thing to look out for would be appreciated. NOTE: I did check the diaphrams and they are functioning and working good. HELP!!!!
 

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i would check the gaskets on the black cover that goes over the spring and pins. Mine werent seated perfectly so it was letting in air, a vacuum leak. Check the choke where it connects to the carb, those break easy and if your choke is stuck open it will do what your describing.
 

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I am unique
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To all,

I am helping a friend out. He brought me an 03/660 Raptor that was running poorly. I did not start the bike, I stripped the quad down and started looking for obvious problems. I took the carbs off and disassembled them. I cleaned everything and replaced all seals, installed a dynojet kit, new needle and seats, and checked the floats (no holes). I put it all back together with some new gas and it started right up. When i mash the throttle wide open all it does is sputter. It almost sounds like its getting enough fuel just to pop but then nothing. I took the carbs back off, re-cleaned them, blew them out with HP air and reassembled and it's still doing the same. This quad has no mods with the exception of the new HI flow intake and filters I installed for him. I'm not a yamaha man (Honda and KTM) and I cannot for the life of me figure this out. The setting on the carb were set to Jetkit recommendations based on 0-3000 ft riding. Any thing to look out for would be appreciated. NOTE: I did check the diaphrams and they are functioning and working good. HELP!!!!
It always helps to know the jetting, since improper jetting can cause your symthom, but it also could the park brake switch stuck on, this causes the park brake rev limiter to engage and once the throttle is applied, it will just sit and pop and sound like it is backfiring...........
Just disconnect it and seal the main harness with silicone at the plug and it wont happen again should this be the problem.........
 

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Master of the Electron
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Read "Most Common Problems With the Raptor 660" sticky at the top of this section (General 660) - pay attention to the Rev Limiter section.
 

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i thought my rev limiter was bad, i disconnected it and it turned out it wasnt the issue. Just have to play around with it until you find what works best...
 

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Master of the Electron
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i thought my rev limiter was bad, i disconnected it and it turned out it wasnt the issue. Just have to play around with it until you find what works best...

And, so, what WAS your issue?
 

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Discussion Starter · #7 ·
I'm still working on it. I appreciate the information. I've been extremely busy with work so I haven't been able to continue investigating the problem. I really think it's an ignition problem. I will keep you posted as soon as I have some time to work on it. Thanks!!!
 

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^^well, it was a combination of little things. My carbs were dirty as shit first off, so i clesned those up really good, and even though i dont normally use additives i used some seafoam additive. Actually worked miracles on the damn thing. I changed the spark plug and the boot/wire. I installed a new k and n filter (no lid).
Im not sure which one it was to be honest, but i know it runs a hundred times better. I still have the damn thing disconnected though, better to keep the issue prevented all together.
 

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Master of the Electron
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It was the carb cleaning - at least to make it run decently again... the rest were a bonus.

I also use Seafoam occasionally as it does work amazingly, in some applications - unstuck a carbon stuck open valve in a Ford Escort once... that was a miracle, as far as I'm concerned.
 
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