Engine had a miss now blowen motor on the exhast side

Y

yamaha-farmboy

New member
Joined
Jan 27, 2013
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6
Age
35
Location
sask
2003 viper mountian 4500 k on it

Cleaned and inspected the carbs all was good took it out for a ride and motor had a miss to it at high speed. Had good look at it adjusted power valves and looked at carbs again all was good so took it out again seem to run good for a few miles no miss then started happening again waasnt long after that it just died pulled all plugs were good but the exhast side one was white as a ghost what could of caused it to lean out or it missing like that.

Thanks
 
well I am guessing your referring to the mag side cylinder(right side of sled while sitting on it) that one and the center one are the famous cylinders that burn up all the time. The causes likely are old gas in the sled from storage and first ride out, low octane fuel in machine, dirty carbs(you said you cleaned them though), float stuck closed/faulty needle-seat, or plugged jet from dirt in tank or faulty fuel filter in tank.

The damage could have been done before when you said it was missing but then you cleaned the carbs, and when you ran it hard it just let go. More then likely the front edge of the piston will be melted away and hence the sparkplug being lean looking.

Take a light and look down the cylinder spark plug hole and take a look at the piston, is it all silver colred or damage to the top of it?

you didnt mention if it has compression or anything??

so youll need to elaborate a bit more in order to help more, kinda flying blind a bit.
 
yes it was the far right side the rope did not want to come out then after a bit it came out a little so amybe just stuck piston not sure yet havent taken it apart. Prior to that ride we did compression test and it was starting from cluth side 90,110,100 would of that caused the miss not even or low compression
 
the vipers have staggerd compression, the pto side is 10-20 psi lower.
compression does seem alittle low but it could just be your gauge.

mine is at 120 140 140
 
"Just a stuck Piston"??? that's not a low level problem in my books.
I would say it warrants a tear down inspection. Funny thing about compression testing is that it doesn't really give you a great "big picture" of what your motor is like. I've had these motors with good compression warm and cold but after a tear down, it's hard to believe they were running as well as they were. You could do a leak down test but at this point, not sure it's worth the effort.

My suggestion, and it's only my suggestion, would be to pull the head at minimum and have a look.

If you're in the Regina area, PM me if you need a hand.
 
pulled it apart found out the prev owner had a hole in the crank case and thought he would jb weld it and then it let loose that explains the miss it had and could not find out what was doing it
Some people he had the motor out why not just fix it the right way
 
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