Yamaha fuel or fire

dbaker72

New Member
Sep 7, 2009
2
0
0
52
i have a 05 660 with a hmf slip on pipe and a cheep after market cdi it has a white epi spring in it also. that was for mud riding with large tires. now my problem is that it is cutting out about half throttle around 25 to 30 mph. it will miss a little on take off with this cdi. but if you hold the throttle down it will still gain speed. i put the stock cdi back in it and at half throttle it will just die unless you let off of the gas. it also done this a few times on take off with the after market cdi. i had it jetted at a shop in town on a dyno so they say the jetting is right i dont know. i also have a new clear inline gas filter on it. can any one help me out?
 

AZCourt

AZ's Finest - UTVUnderground Approved
Feb 11, 2009
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Sounds like jetting. What jetting is in it?

You can only do the main jet on most Dynos, therefore the part throttle stuff gets missed.
 

cls 78

Valentine Motorsports - UTVUnderground Approved
Feb 3, 2009
64
3
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Norco
Just a thought, check the reverse signal wire under the air box. I had the same problem and re jetted about 10 times and discovered the problem was this connection. When you pull the airbox completely you will see it, crimp the plug lightly and push back onto the engine. See if it works, it did for me.

Just my .02

Mike
 

BlackRhinoPerformance

BRP Site Sponsor - UTVUnderground Approved
My guess would be bad gas or crap in the gas has plugged up a jet or two. I've had to tear down carbs and blow out all the jets and jetways on a couple of machines that were running similar to what you're describing.

Hot tip is to always run fuel stabilizer, gas these days starts going bad in 3 weeks.
 

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