I own a 92 Yamaha Timberwolf that was converted from an 82 Yamaha YT175 3 wheeler.

It starts and idles only when the choke is fully on. Even after 10 minutes of reving the engine it stalls if the choke is not on.

When i put it in gear and rev it up, it spudders and stalls. After a few tries at this it will sometimes go, but still stall when I let off the throttle. It seemed like the gas/air mixture was wrong.

Naturally, I blamed the carburator so I removed it, overhauled it, cleaned it up, forced air through the jets and it still does the exact same thing as before. I then adjusted the pilot air screw and the idle screw according to the manual and that didn't help either.

I also made sure the gas lines weren't obstructed and that the fuel pump was working fine.

Everything seems to be in order so I'm stumped. [img]i/expressions/face-icon-small-tongue.gif[/img]
If anyone has any suggestions I would really appreciate them. Thanx.

 

it sounds like it may be extremely lean and needs the extra gas from the choke to stay running.

 

Do you have any suggestions on how to adjust this...?

 

take the bowl off the carb and change the main jet. you should probably go up 3 or 4 jet sizes

 

Thanx, i'll try that....my main jet now is 170

 

The weird thing though is that the machine was running fine before with the old jets...i wonder what caused this problem? Could something have rattled loose/off. I was riding a really bumpy field right before it happened...

 

Are the jet sizes in increments of 5? (eg. 170, 175, 180, 185)

 

Is the weather different? Altaitude, and weather also affect jetting because it changes the air. Also, humid weather can trick your motor into thinking it is getting no air.

 

I wouldn't go changing jets yet. Is the gas old? Maybe water in it? Is the air filter clean/dry? Is there a birdnest or mice in the airbox? It sounds to me like you've got crap in the carb or something blocking your air.

 

Agreed....If it was running fine befroe...then yes something has happened. Do not start swapping jets. Take the carb off and inspect it. Make sure your float level has not changed. Clean the whole carb 100%...pilot, main...check the fuel seat/valve. Clean the filter and airbox.

I bet you find your problem when you take the carb off.