Yamaha Grizzly Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter #1
Looking for some advice on a pesky problem I'm having with my 660. As background, it has about 225 miles on it. About 75 miles or so ago, at idle it will occasionally backfire and stall or just backfire or miss. Also, occasionally, when engaging the throttle to move out, it will stall. Also, it I keep the power on just slightly in gear and roll, say at 3 miles per hour, it will lightly back fire about every 5 seconds or so.

I tried changing the spark plug, still doing same.
Cleaned the air filter, even took it out and let it idle to see if change. Still dong same.
Increased the idle speed a turn or so. Still doing same.

Once I get past the low rpm problem I.m describing, quade runs great. Never does it when under power more than idle or just slightly above.

Any suggestions?

Thanks.
BC
 

·
Premium Member
Joined
·
324 Posts
BC I have been reading lots about carberation lately and from what your say it

seams your problem is with your mixture screw. The mix screw only works from

idle to 1/8 throttle. Let it idle for a bit and pull the plug if it's white

turn the screw clockwise 1 turn to richen. If it's wet maybe 1 turn

the other way. If that doesn't fix it take the bottom of the carb off and see

if the piolet jet is plugged. Oh hey, it would make your life a little

easier if you can make a 2 inch flat screwdriver to do these adjustments

you'll see what I mean if you attemt this. This is my guess to your

problems, I hope it helps (i'm no pro mechanic)
 

·
Registered
Joined
·
34 Posts
Backfireing is a sure sign of a lean condition. (Not enough fuel mixed with the air entering the motor) I would start with the idle mixture screw as ad2md suggested. If you run out of adjustment on the screw remove the carb from the machine. After you clean it off, take the float bowl off the bottom. Take the float/s out (don't lose the little pin they pivot on). Now make sure the pilot jet is not plugged with dirt or water. If it is open then I would remove the jet (it should be threaded) and take it to your local motorcycle shop and ask for the next size larger jet. Reinstall jet and carburator and adjust the screw again as needed. With the screw, some are air screws and some are fuel screws and the direction you turn it are different. Not sure about the griz, I never had mine apart but the book should say what way to turn for richer/leaner. Hope that helps.
 

·
Premium Member
Joined
·
2,962 Posts
Before you start messing with your carberator, it sounds like your intake valves have tightened up. This is very common with the 660. I don't have the owners manuel with me, but you are supposed to have your valves checked at 250 or 500 miles. Almost every 660 whether Raptor or Grizzly have the intake valves tighten up and run lean. Adjust the valves and you will have a whole new machine.
 

·
Registered
Joined
·
16 Posts
I agree with starky and addicted on this one. would adjust valves fist though as starky suggested, due to the common occurence of valves tighting on most 660's. If that don't help than mess with your air/fuel mixture. this should take care of your problem.
 

·
Registered
Joined
·
9 Posts
Discussion Starter #6
Thanks all for the advice. Haven't adjusted the valves yet so will give that a try first.

Thanks again.
 
1 - 6 of 6 Posts
Top