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[Norm]

Hi All, testing my memory a bit here but can anybody give me an idea as to the amount of suction I could expect from a 125. I know it is a bit hard to explain but by puting your fingers across the inlet port how hard should it pull on your fingers. This motor was apparently reconditioned but has been sitting for a long time so I'm tipping it will need new seals. I assume they are still available

[scotty]

Norm if the engine has been unused for a bit might need a bit of oil down the plughole to give a good seal with pistonrings also depends how fast you turn motor over . local bearing services should be able to get seals only weird ones are in twin 2 strokes, should feel slight suction at carb/inlet as you crank. best of luck.

[Presto]

Hi Norm - most small 2 strokes run with very low crankcase compression, so you'd feel only weak suction at the carb. They also have low cylinder compression, esp if its calculated after all ports are closed. I wouldn't assume seals have failed until you're sure crankcase compression - and suction - are almost zero.

[Anders F. R.]

A 2-stroke engine with worn out (or otherwise poor) crankcase seals wil typically run poorly. It will have a tendency to rush at idle, suddenly increasing rpm for no obvious reason. It will often 4-stroke more than normal andwill not pull normally.

If your engine doesn't have any of these symptoms, I would not spend time and money to dismantle it unless other reasons make it necessary.

I have had two Sachs 2-strokes that behaved like described, one from 1958 and one a little newer. The first one was cured completely with new crankcase seals. The next one was dismantled and obviously was in need of new seals but was sold as a "diy kit".

My current Sachs 175 engine is a 1964 which has done only 10000 km since new. It has never been opened. Nothing at all indicates poor seals, even if it is almost 40 years old.

Summary: Don't assume it needs new seals just because it hasn't been run for a long time. Try it, and then decide.

Regards, Anders F. R.

[Norm]

Thanks Scotty, Presto and Anders, this is a Flea , I can get it to fire and run for a few strokes by giving it a taste of Start ya Bastard but that is all, I have tried a couple of carbs and one from a 125 motor mower and I get the same result. Proof is that spark and timing are ok so it is a fueling problem and this is what makes me suspicious of seals and why I was trying to find an indication of the amount of suction I could/should expect