Greetings from Houston,

I'm the original owner of a 1985 Yamaha Moto-4 80 and have been working on it a little here and there to try and get it running for my son. I consider it a pretty cool quest to have him up and riding the same Yamaha I rode as a kid. The problem is I can't get it to turn over.

Anyway, the 4wheeler had been garaged at my grandparents up in Dallas for 20 years, and the gas in the tank and carburetor had turned to varnish and the air filter was rotten to the point of falling apart.

Here's what I've done so far:
-Replaced the battery. Full Charge. Have good strong neutral light when I turn the key.
-Took off the carb, disassembled it and ran it through an ultrasonic cleaner. (Here's where I think I may have messed up as the simple green/water solution pitted the aluminum...learned a lesson there) Float was fine. Jets seemed clear but the main nozzle was very difficult to remove and get back in and the main jet doesn't thread flush with the alum body of the carb (not sure if it is supposed to, but there is definitely a gap there.) I also noticed that the choke was a little slow in closing but figured that could be due to it being dry. When wet it seemed to open and close okay so I figured with gas in the carb it would probably be ok. I was careful to back out the jet 2.5 turns per the manual. Re-assembled carb and re-installed with new O-rings and new gaskets.
-Replaced the air filter with a new one (oiled it per instructions)
-Cleaned out the gas tank and confirmed that gas flows through the gas line
-Replaced the spark plug (checked the gap)
-Cleaned the muffler element
-Checked the gas tank breather hose, its not plugged
-checked the carb breather, not plugged
-fuel empties from the carb when you unscrew the drain valve

When I tried starting it wouldn't turn over and flooded the engine. The pistons are making the thud thud thud like they are moving up and down. The break is engaged, run switch is on, fuel is on (obviously). I performed a spark plug test and I'm getting a spark, but I did notice a very small amount of black almost like grease on the spark plug electrode. I also did the thumb over the spark plug hole compression test and seem to be getting plenty of compression.

The main nozzle and jets can't be purchased for this model anymore, and other than replacing the carb I'm out of ideas. Before I cough up another $80(for an aftermarket) or $250(for OEM) carb I'd appreciate if anyone else with experience on this model could weigh in on potential problems based on the above diagnostics.

Thanks in advance!

 

Geeze bro thats all i can think of, it might just b to ald