Blown 80cc HT engine

[Frankfort MB's]

i was riding my ported 80cc and over a 1-2 mile range it tended to foul the plug out... Let bike sit a little then tried again and the bike was locked up and would not come loose... Just wanted to know what problem could be even though I'm just going to buy a new kit

 

[crassius]

could be that plug didn't foul, but your piston seized

 

[Frankfort MB's]

I know that it did foul because the spark plug was covered in oil, the piston wasnt seized then it just didn't run right... My thoughts are that the motor got to hot from riding with slower traffic

 

[crassius]

then a new plug should get it running

 

[Frankfort MB's]

The motor is locked up... Took head off and the piston won't even move... Tried 2stroke oil to lube it up no dice, I'll yank it apart in the next few days to get the real truth behind the mystery

 

[Timbone]

I am working on my third engine. None of the three ever seized. Since compression is so low, I would posit that seizure would be caused by 1) lack of oil or 2) block warp caused by excessive heat/ very high mileage.

 

[Frankfort MB's]

I was running 30-1 oil with synthetic echo chainsaw oil and the engine has about 150 miles.... I was actually at a really big car show in Tennessee and the traffic only goes like 15mph and I can cruise a little faster riding on the side of the road, people love these things down there so of course I have to do the requested burnout or revving lol

 

[Timbone]

15 mph on a 44T sproket would be a decent RPM at low load. Maybe hours of this would be a problem.

If I wanted to seize the engine I would run high RPM with low oil and lean mixture. Or maybe WOT on a steep hill i.e. high load. I think 30:1 mix is good.

Let us know what you find.

 

[Frankfort MB's]

I would get up to about 30-35 just to race a couple guys on stretched mopeds with slicks after all what are these motors for?

 

[Frankfort MB's]

Opened up the motor tonight and saw a couple fragments of what looked like a piston ring (I accidentally broke 2 sets putting the cylinder on) took those out then motor freed up so I'm going to order my head gasket then I'm gonna test her out... Should have lightened my piston when I had it out another day....