Engine troubles

lilred

New Member
Dec 9, 2008
19
0
0
Perrysburg, Oh
I have a 2000 yamaha blaster. I was riding it tonight in the snow and was coming across a field at close to WOT and the engine made a clicking noise and then started bogging. So i started to down shift and give it gas and it started to accelerate agian but with less power. I continued on and as I was slowing to turn around it stalled as the rpm's got lower. I tried to get it to refire but no luck. I pulled it home and checked spark which it has. It seems to have good compression when i stick my finger over the sprk plug hole. It is also getting gas. I pulled the carb and reeds off, the piston and rings look good from what i can see. The only thing that I noticed was one of the reeds is hanging open just a bit and the end of it is chipped and frayed looking. The reeds are stockers.

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yea your one reed looks damaged, i would get a compression tester and try it again. if it was me i would pull the jug and have a look at the cylinder/piston make sure every thing looks good and in working order.
 
yea it shouldn't be that much should cost ya $50 or so for a bore and hone then about $90 for a piston kit and another $20 for a gasket kit then your good to go.
 
how long were you holding it wot without changing rpm's ????
thats bad news imo, and i've made one last over 8 years of my punishment
always warm it up completely and never hold it at one rpm for long, especially wot
 
I would check out vitos for a piston kit. They run around 130.00 for piston, rings, bearing, wristpin, cir-clips and gasket set. If your cylinder is not damaged you can go back stock. Myself if I had to do one I would go .020 or .040 over and have the cylinder bored for $30.00+.
 
i'd stay away from the vito's junk, they're cast and prone to breakage, theres only one piston imo, a wiseco forged piston for around the same $$$
 
If you didn't have the reeds in you won't get an accurate compression test. Your actual cranking compression will depend on the guage, altitude and engine temperature as well as the condition of the engines parts. Those reeds are in bad condition and should be replaced, I suspect they are a big part of your problem. You can pull off the exhaust and examine the exhaust side of the pistong skirt/rings, this can be very helpfull in determining internal condition because most piston damage is usually on the exhaust side. I would check the exhaust side of the piston, if it looks good then replace the reeds/gaskets and do an other compression test holding the throttle wide open and kicking untill the guage stops moving. The guage should have a threaded end approximately the same length as the spark plug threads and have a schrader valve in the end to give a more accurate reading. Remember that compression values will be lower at high elevations and lower on a cold engine. Anything below about 100psi is unserviceable and should be diagnosed/rebuilt.
-Brandon
 
I did have the reeds in when i did the test. I will pull the exhuast off and check it out before complete tear down. I was also not quite at WOT, i was accelerating in fifth and getting ready to shift into sixth.