Yamaha yt125 help

[83ATC185S]

Been messing around with my 1982(i think) 125 yamaha, cant get it to run

Have 90lbs compression,cleaned the carb,getting gas to it,cleaned the reeds,have spark,plug looks new. running premix gas. Still cant get it to fire at all. Its been sucking at the carb like it should,and puffing out the exhaust

Im not familiar with 2strokes so any help would be great. Im running out of ideas on what to check.

I dont have a manual so im doing this kinda blind too. Thanks for any help

[Yamaha_Rules69]

Have you tried giving it a shot of starting fluid in the spark plug hole? 90psi sounds a little low, I think it should be at least 100psi to run. It could need a new set of rings/hone, or new piston and bored out, but you will not know until you take it apart. Does it backfire when you pull on the rope, and jerk your arm? If so, it could be out of time (flywheel key) Heres what I would do,the starting fluid dosnt start it, pull start it behind another atv/vehicle, and see if you can get it to start. If it starts this way, and runs okay, but will not start by pulling it over, the compression is just too low to start by hand. Give this a try, and see what happens! Good luck

[83ATC185S]

I havent tried the starting fluid in the spark plug hole, I sprayed a little in the carb. It doesnt backfire or even sputter (even on spray)

Pullstarting it isnt an option, I have no chain for it right now. I was just trying to see if I could get it to fire and figure out weather or not its worth a new chain/tires ect ect. If 90psi is too low to even start,and i need new rings or a bore and hone. Then this little yamaha is going to sit and rot in my backyard. I would rather put money into my honda's.

Thanks alot for all the info!

[flowmasterman]

all you need is air,fuel,and compression,and spark! 90 lbs is enough to run, take the plug out to see if it is wet after pulling on it,that will tell you if it getting gas to it,if plug is wet, check the plug for spark, and just because it has spark at the plug doesn't mean it will run with that spark, it needs to be a fat blue spark in between the electrode and end of the plug. could just be a bad plug. And I hate to ask.but is the kill switch in the on position? on 80-81 the kill switch is a push button type, and if the decal on top of button is wore off you can't tell which is on or off unless you already know. OFF will be pushed in where button is flush with the switch, off is where button is sticking out of switch,but if it an 82 like you think it will have a flip switch and thumb throttle. only other thing could be coil,,which i doubt, or the CDI box, cant get out of time unless the keyway on crank stripped out because has a magnectic pick up on flywheel.

[sandpuppi101]

Hey 83ATC185S I have one and I'm kinda in the same boat as you but mine run's.90 psi is deffinatly on the low end of compression and althoough it may run it's gonna be an issue for you.I may sell mine or if you wanna start selling part's off your's I mite buy some stuff.Let me know by PM if ya wanna sell some part's.I know another guy who'd be interested in some of your part's if ya decide your gonna part it out...

[old-yellow]

The stock compression is 100PSI for the YT125 so being 10 psi low is not a big deal it will run just fine like that, but you should check the the flywheel key to make sure its not broke, If not then I would try testing the magnectic pick to see if it went bad and is throwing the timing off.