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Help required with MAG Engine, please

Can anyone help please? I have got a MAG twin cylinder petrol engine in a mower. It has a 'Burtler' carburettor. My problem is that I cannot get the engine to idle properly, it either revs away or dies. I have checked everything obvious, such as air leaks, valve guides, spark etc, and stripped and cleaned the carburettor, but all to no avail. When I first got the engine it had no bowl on the carburettor, but I found that a glass AC water trap bowl fitted perfectly, except that it is about an inch deeper than the original. Would this make a difference? If so has anyone a scrap carburettor / engine lurking in the nettles, or suggest another carb that I could acquire? It is a very simple one, with about 1 inch bore. The engine is 525 cc. Would a motorbike one work?

Hope somebody can help, the football club wants to cut it's grass!!

Cheers, Barleycorn.

Reply to
Barleycorn
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I dunno about the original, but certainly a motorcycle carb for a similar sized engine would work. Motorcycle carbs are a lot more sophisticated and tuneable - however, it would certainly need fiddling with it to make it work well.

The float bowl should make no difference as it is the float level that decides the mixture, not the depth of the bowl.

My money would be on an air leak. I'd take the carb off and face off the flange on a bit of glass with 400 grit wet & dry stuck to it with water. If it is a socket type carb, investigate the sealing. Fit a new gasket made from a cereal packet & use a decent gasket cement.

Regards,

Kim Siddorn

Reply to
J K Siddorn

Thanks, Kim, I did as you said and sealed all the inlet manifold, but still it ran erratically. I think that I have got to the bottom of it. The engine was standing for several years outside, and I think that the rings on one of the pistons have stuck, presumably the one where the valve was open. I poured some Redex into the bores today, and one cylinder held it, while it drained away in the other. I have poured Redex through the carb, and have mixed a bit with the petrol. It seems to be getting better, I can now get it to tick over sort of, but have set it so the governor opens it up a bit before it dies. We are going to cut the football pitch with it tomorrow, and I hope that after a few hours running it will get a lot better.

Thanks again for your help, Barleycorn.

Reply to
Barleycorn

Yeah, give it something to do, blow the cobwebs out, reseal the piston rings with nice fresh carbon. Always works

But if you are right and the valve face is pitted, you're going to need to get it out and grind it in. Redex isn't THAT good ;o))

Regards,

Kim Siddorn, Regia Anglorum

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Reply to
J K Siddorn

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