Yamaha G1 poor performance when starting from dead stop

[klg404]

Hi all,
Just picked up a 79 G1 last week and starting to go through it. I cleaned the driven clutch (helped enormously) and now I'm starting to trouble shoot other issues. The one I can't seem to figure out is that once the cart comes to a complete stop and turns off, it has trouble starting again. I will have to pump the gas pedal a few times to get it going again. There have been times that I actually had to put it in reverse, then forward to get it started. I have replaced the spark plug, checked that the fuel pump is pulsing, and did a quick cleaning of the carburetor. I also tried adjusting the air screw with no results. Any other things I can try??? Thanks.

-klg404

[smallblock450sl]

Welcome to BGW First, need to know if when you push on the pedal, does the engine not turn over or it won't fire up.

[klg404]

Originally Posted by smallblock450sl

Welcome to BGW First, need to know if when you push on the pedal, does the engine not turn over or it won't fire up.

Thanks!

The engine does turn over, but doesn't fire up. I always have to either choke it a little bit, or pump the gas pedal. Seems like it is a fuel delivery issue...so I pulled the fuel pump line from the carburetor, then hit the gas. The gas is pumping (or pulsing) just fine into the carb...

-kg

[sho305]

It is very common for those to have so many hours on them the crank seals are bad/leaking. You will see oil near the seals or can spray around them and it changes engine speed. The compression could also be low from wear. Used to be cheap to get a bored cylinder and piston I have not looked in some time, but then you have a whole new top end and it will run like new. I've seen bad reeds in the intake also that don't close. Saw one the piston skirt was broke off and it only started with choke, amazing it didn't grenade. You could have some other issue, but this is common on old G1 if it don't start in a couple seconds. They can also plug up the exhaust, you can take the header loose from the cylinder and test start it (with it leaking badly, to test for backpressure).If it fires much faster you would know. Also stick something up the tailpipe and make sure its clear.

[slonomo]

Originally Posted by sho305

It is very common for those to have so many hours on them the crank seals are bad/leaking. You will see oil near the seals or can spray around them and it changes engine speed. The compression could also be low from wear. Used to be cheap to get a bored cylinder and piston I have not looked in some time, but then you have a whole new top end and it will run like new. I've seen bad reeds in the intake also that don't close. Saw one the piston skirt was broke off and it only started with choke, amazing it didn't grenade. You could have some other issue, but this is common on old G1 if it don't start in a couple seconds. They can also plug up the exhaust, you can take the header loose from the cylinder and test start it (with it leaking badly, to test for backpressure).If it fires much faster you would know. Also stick something up the tailpipe and make sure its clear.

Ditto! Need to pull the engine and have a look. It's pretty easy to pull it out, and doesn't really take much to take the head off. Might tell you a lot. You can see the rings from the exhaust, although if one is cracked you'll have to pull the piston to see that.

[klg404]

Thanks guys, I'll take a look this weekend.

-Kg