OK I have put a new top end kit on it. Compression is 115-120#. The carburetor is new. Has spark and gas. I can get it to run for a few seconds only if I spray starting fluid in it but cannot keep it running. Just barely firing off for a few seconds. I have pulled the exhaust and cleaned it out to make sure its not plugged. Only thing I can come up with is the CDI box. The CDI box is about $200. Just want to see if anyone else has any ideas before I throw more money at it.


Anyone know the best place to get a CDI Box?

 

$200 for something that doesn't exist, sounds reasonable. The ignition coil is the CDI on the LT50, the exciter coil behind the flywheel is more likely to give trouble. Disconnect both kill switches, fit a new plug and try again.

However your problem is fairly certain to be fuel. Are you starting it on prime? does fuel flow into the carb full bore on prime? Have you tried cleaning the new carb out? The float needle is a weird device on the LT50, are you sure the float level is correct.

If you do need electrical parts, used ones from breakers are cheap, because they are not much called for.

 

Replace the crank seals? Most people over look these when they do top ends and doesn't matter how good the top end may be and even it's getting fuel and good spark,if the seal(s) are leaking it can't compress the air/fuel/oil mixture in the crank case and shoot it up the transfer ports for ignition.They may kick off a little on starting fluid since it so light versus gas.

 

With the comp at 115+ I'm thinking carb related also.
To check the stator and coil, use a ohm meter.

 

Thought it did have a CDI and its built in with coil. All one piece

 

Guess I will have to look into that.

 

I have OHM meter. If it was only fuel you would think I could keep it running on starting fluid. Maybe not. I am not sure. I build all kinds of car race motors but this little thing has me stumped. It is frustrating. I read where you have to split the case to replace crank seals. I just want to figure out the problem for sure before I just go to replacing more stuff.