96 yamaha g-16 -no start and backfires

[badboy72811]

the rockers are not moving.it still turns over ,i cant get the clutch off to see what broke.anybody have any idea what broke. i am not really worried about fixing the motor,i have a 500 cc arctic cat motor i am getting ready to drop in there.anybody know if there is neutral position on a 96 g-16. or if the clutch on the snowmobile motor will make it so i dont have to worry about neutral.

[Mike Mac]

Are the push rods still under one side of the rockers/tappits? Are you saying that when you turn the motor over by hand or with starter, the valves don't open? nothing is moving inside the valve cover?

Usually when this happens, the valve adjustment is way to loose, and the push rod slips out from under the rocker arm.

[badboy72811]

yea nothing moves inside the tappet cover,one rocker arm is really tight and the other one is really loose.and they are under one side of the rockers

[Mike Mac]

At this point if there is no movement of the rockers, and the push rods are not going up and down,well, it sounds like a stripped cam gear. But hard to believe, if it was running not very long ago. Might be time to pull the clutch off, and pull the side cover off the case. But it doesn't sound like good news!

[badboy72811]

i thought it was running fine.but it did seem a little doggy the last week or so.i have already tried to pull the clutch off. i used a puller but it didnt come off,it actually chipped part of the pully.i am going to get it apart to see what happened.i will probably rebuild the motor or i might sell the starter and scrap the rest of the motor.i am just about ready to drop the snowmobile motor in.both motors are out,all i got to do before i drop it in is clean the carbs and adjust them a little bit.i havent ran the snowmobile the past three years cause my kid broke the suspension on it.i will post on here when i get the motor apart let you know what was broke-thanks for the help.

[Mike Mac]

Helps to have the specific clutch puller for the clutch (to keep from damaging it). Before you tear it apart, I would reevaluate the situation, its uncommon for the cam not to be turning. Take the rocker assembly off and feel if the cam is moving with the pushrods and a flashlight. Does it make any unusual sounds or feel like its grinding, when you turn it over by hand. Dump the oil, and check for parts or metal shavings etc.
Good luck, Mike

[badboy72811]

it doesnt make any unusual sounds,before it quit my kid said it made a flapping noise. i thought maybe the timing belt, but not sure.

[Mike Mac]

Does it feel like it has compression at the compression stroke, meaning, does it feel like its coming up on compression every 2'nd revolution? Sorry, don't know how savvy you are with engines!!

Also, you should be able to push the valve open with your fingers. valve springs are weak. Wonder if a valve kissed the piston and bent. I'd pull the head before you crack the case. A bent valve might be hung open.

[badboy72811]

it has compression,i cant push the valve open.

[Mike Mac]

A wild guess, is a bent valve stem. you should be able to push the valve side rocker down to open the valve. The springs are not that strong. This is at TDC of the compression stroke, both valves closed.