1956 Royal Enfield engine problem. Help!

[lilcb1]

I have a 1956 Royal Enfield 150cc 2 Stroke. Up until last week it was running perfect. The problem I'm having now is that it back fires. It doesn't backfire through the exhaust but through the carburetor and through the air filter. I did crank case air leak test and found a leak. I repaired it and started the motor up yesterday and it still back fires. I adjusted the timing to 5/32 before TDC with a .013 gap on the points. Tried to start it up and it still back fires. The carburetor I have is an old Amal carb. Could it be the carburetor?

 

[Sonreir]

Probably. Check the jets and make sure there isn't anything plugging them up. Spitting through the carbs usually has to do with running lean. With a four-stroke that is...

Two strokes, possibly the same?

 

[lilcb1]

Thanks! I'll clean out the carbs again and see if anything is stuck or blocking something.

 

[lilcb1]

I cleaned out the carbs and its still the same...Does anyone else know what it can be?

 

[Sonreir]

A leak in the engine cases may be introducing additional air. Any sign of something like that? I know two strokes like/need to be buttoned up pretty tightly.

 

[lilcb1]

I did a test and found a leak. I repaired it but it was the same. I'll do another leak test and see what happens. Its freaking frustrating.

 

[VonYinzer]

Whe was the last time the motor was rebuilt?

 

[lilcb1]

Honestly, I don't think the motor has ever been rebuilt.