help w/old aircooled 2stroke

[ellandoh]

1980 honda odyssey wont start?? it has an aircooled 250cc motor. has no exhaust or intake valves, it uses cutaways in the piston . i have checked for air, (CLEANED CARB)fuel, spark is strong. tried starting fluid and get an occasional pop every 15 pulls. if i pull the plug and leave it near the plug port i get lots of fire. im guessing the next step is to check timing...................ANY MORE IDEAS????

THANKS IN ADVANCE
L&O

 

[_JOE_]

As long as it has good compression, timing would be my next move. If timing looks good I'd pressure test the motor. On something that old it very well could have a dried out/worn crank seal.

 

[2strokerfun]

It's basically a detuned '75-'76 elsinore engine with a few modifications. Does it have a CDI or points?? Some had points. Later ones had CDI. If it has points, the timing is not very adjustable except for points gap. If you have points, clean them (running old soft dollar bill through them several times often works) and set the gap. Also, you could have worn out top end. The last time I bought one of these engines, someone had put the piston in backwards and snagged the ends of the rings on the exhaust port. They are very straightforward piston port engines. If you are getting good spark, and timing isn't way off, I tend to look for carburetion or air leak issues. As Joe said, check the seals. You do have to split the cases, though, to replace the seals. Start with choke on, no throttle. Keep us posted. I think the Odyssey's were way cool machines.

 

[MikeT]

He said he's getting a spark so I think the timing idea is one to be looked at. It could have a sheared flywheel key also. Give that a check and make sure you are using fresh gas, clean air filter.

 

[dirt bike dave]

It could have a sheared flywheel key also.

That's what I was thinking, too.

Nice spark, but just coming at the wrong time. That could make it hard to fire, even when using starting fluid.

Bad reeds, stale gas and low compression can all make a two stroke motor hard to start, but it should still light up for at least a few seconds when using starting fluid.

FWIW, I had a sheared woodruff key on an old KDX once, and it behaved exactly like your Odyssey.

 

[ellandoh]

good ideas fellas , timing and flywheel key are on the agenda friday directly after the sweat shop :whoa:

 

[RM_guy]

Check to make sure the choke is working. I went to start my lawnmower last night and pulled and pulled so I started to take off the carb to clean it out. Turns out the cable that actautes the choke wasn't working so it never fully closed. Fix that and it started right up.

 

[MikeT]

good ideas fellas , timing and flywheel key are on the agenda friday directly after the sweat shop :whoa:

Make sure you remove the flywheel and look at the key. If it is deformed even a little, you need to replace it. A little deformation visually will make a lot of difference in the timing.