tomos a3 engine trouble

ok i have a 1978 tomos sport.... with an a3 engine i have always had problems with it idling... and now i cant get it to start and stay going. i can get it going and it revs for a few seconds then it just dies. i have cleaned out the carb and the spark is good.

could this be the timming or maybe a bad piston ring ?....

Re: tomos a3 engine trouble

you may have a vacuum leak. Check for leaks in all joints in between the carburetor and the head.

There are a couple ways to check for leaks, but since you can't keep this thing running, just take off the carb and the intake manifold (if it has one) and perhaps reed valve cage (between the carb and engine, if it has one).

All these parts have gaskets or O-rings between them for sealing the joints.

Your bike's a '78.. almost 30 years old.. and if these gaskets / O-rings are original, one or more of them of them is very likely no longer sealing.

Get a tube of Permatex 2 (non-hardening gasket sealant) and put a thin coat on both sides of the gaskets .. reassemble.. test..

Re: tomos a3 engine trouble

Eric Everyday /

wow dont i feel like a fool. after looking at my moped again and thinking about it i decided to check the spark even tho i just replaced the plug.... and guess what the plug was bad. so i got another new one and she runs like a champ.. im going to see if sealing it up will help it idle beter..

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