The Craftmans Shop > New from Old

New Cylinder and Piston for TS350 Petrol Saw

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Bob-tech:
The seals are very important for a predictable and stable tick-over. When they leak air you never get a constant carburation in tick-over and it will be impossible to adjust the carb. The seals are just ordinary Simmerrings. There is an impulse connection between crankcase and carburator. This might be a hose or a fixed connection with gaskets. This could also be the problem.

You can test the hose and the seals by spraying it with brake cleaner while the saw/cutter runs. It this changes the idle speed the seals are shot. An indicator towards shot seals is also when the saw changes idle speed when turning it to the side. The seals can be changed without splitting the crankcase, but you have to remove the clutch and the flywheel. There are left hand threads around. An impact wrench is useful to loosen screws without locking the piston.

awemawson:
Carburettor gasket and diaphragm kit arrived yesterday, so I pulled it all apart again, and rebuilt the carb. Turns out that a previous person had assembled it in the wrong order, the gasket for the pump diaphragm being on the wrong side. Also the tiny 'o' rings on the low and high speed jet needles were missing - these seal the thread of the needle to the carb body. Fortunately I had suitable O rings, but had to make their backing washers by turning down standard 4 mm ones as the o/d was too large.

No pictures but here is an excellent video that I followed:



Then having made a flywheel puller (M25 by 1.5 mm pitch for future reference) I set too and replaced the crank case seals

She now starts and runs, but I can't set the idle speed low enough - I suspect that the throttle butterfly mounting shaft may be a bit worn though it feels not too bad. The one for the choke is  quite worn, but I can't see how that can affect anything when the choke is fully open anyway  :scratch:

Somewhere along the way the Stop switch has ceased to work - I may rob one off the other saw.

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