Hi all. I have a 2003 raptor 660r le. When I start it, it sounds a little rough and when i give it a right thumb squirt it go's boggy and pops out the exhaust. I have looked at the forums on the net and found that people are saying parking brake and so on. So here is a list of what I have done. I have removed and had the carbs rebuilt. Had them properly tuned from my local shop. Had the electrics removed and tested including cdi voltage reg stator and coil (not sure about pickup). Removed park brake and neautral switches and bridged the two bullet connectors. Grounded the reverse swith off the bottom of the crank case. Checked for breaks on all the wires in the loom with multi meter (all ok). Removed the engine top cover and triple checked the timing marks. Replaced the spark plug and set to correct gap. Adjusted the tappets. One thing that I did find was the rotational direction sensor has a higher resistance than specified. The quad is stock standard. At the moment I am willing to try anything to get this thing up and running cause im going crazy that i cant ride my quad. Oh also forgot to mention I am in Australia not sure if that makes a difference to the details of the quad. I dont want to buy any unneccessary electrical parts. Are there any other tests I can do to single this damn problem out

 

Classic lean for some reason. Could be lots of things.
Dirty main jets.
Leak between the carb and head.
Jetted lean.

Pull the choke on and give it a try. How does it run like this?
What do the plugs look like?

 

with the choke on it still pops and farts but smells really rich out the exhaust. UPDATE. Ran a timing light on it and as it revved the light dimmed. Swapped coils but made no difference. Has a new plug in it. it is black and looks wet

 

is it hard to crank? What kind of shape is air filter in? Did you check the readings [ohms] on plug boots?

 

when it started playing up I replaced the air cleaner with a new k&n one. Cranks over fine without an issue. checked the plug boot resistance and its in spec. Its so confusing I just cant narrow it down.

 

im not sure wether it is a stator/pickup coil issue. If the spark plug was white and not wet it would indicate that it is firing consistently. After i give the throttle a squirt and it goes boggy i can stop the engine, pull the plug and inspect it, it is black and wet. Just seems like it is dropping out on spark

 

What you mean by cranking over good? cranks up and runs good? or turns over good without running?

 

cranks over good and starts and idles ok. idle sounds a bit rough though

 

How old is the fuel? Bad fuel could make it sputter and back fire. Seen that happen a few times.

 

yep thats why my father;s 660r kept popping because of bad fuel
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2001 yamaha raptor 660r(father's)
1995 yamaha warrior 350(borrowing)
2008 yamaha raptor 250(soon)
2006 yamaha raptor 80