Engine Trouble A80 2stroke overheating carb boiling spark plug lead burning

[Westie]

So I pulled the carby apart blew it all out put it back together and put a new fuel filter on went to start it up and could feel air coming out the block when I cranked it over so I checked the nuts on the head and they were a little lose so i tightened them up and it's running much better will take it for a big ride tomoro and see how it go's thanks for all your help

 

[HeadSmess]

ooooh, loose head gasket. could do it too.

that one will usually make a squeaking popping sound when you first start up, and clears up as it gets warmer. unless the nuts were really loose.

anyways. hope it goes better now

 

[Easyrider]

Hello Westie,

I'm a new builder trying to fine tune my engine - A80 high compression 2013 motor. I was fooled for a long time looking for bad running solutions. I'm now making progress, but the bad engineering on the intake manifold was so poor the carbie would not slide fully on and no matter how hard I tightened it on, there was still an air leak, I discovered. If the air leak is big enough it will make the engine run so lean it will overheat. My solution was to grind down the over-weld which stopped the carbie sliding fully on to the manifold, and then using an o-ring ($2 from $2 shop) to inset into the carby so that an air seal was made. Then the engine ran too rich (but cooler). I've just put a smaller jet in (from a wrecked scooter - a .65), and wow, what a difference. I've just ordered some Dellorto jets online at www.gpsimports.com.au (only $3.50 each! but postage too!). I'll look forward to getting it running really smoothly, with the help of this forum. It has been quite a lot of work, but testing for the air leak was the initial key - I used the propane gas method. But the basics must be right first before other modifications and trials are made otherwise money can be unnecessarily spent . Good luck