backfire when warm

[briggs206]

im going to look at a 1974 white top lawn boy with a issue of popping and backfiring when it warms up. any suggestions on this problem before I buy it? im worried it may be a compression issue and I don't want to have to sink money into it. its 45 obo and selfpropelled.

 

[Two-Stroke]

That could be an ignition issue -- if it's a '74 it almost certainly has points, condenser, etc. If the compression feels strong and smooth I wouldn't worry about that.

I have a 1974 model 8232 (D-series, self-propelled) and I really like the look of it -- it's distinctively mid-1970s. I'm less thrilled about the design of the self-propelled mechanism -- I wish I had the same mower without that stuff.

Do you know the model number?

Bottom line: if it looks mint or near mint, it might be worth $45 -- given that it has this engine issue. I'd offer less or maybe pass. Please let us know how this comes out.

 

[jp1961]

I've never heard a two stroke backfire,,,isn't a backfire a 4 cycle problem when the engine fires on the exhaust stroke??? Like the other post said, may be an ignition problem or maybe the exhaust ports are carboned up. Another item to check is if the flywheel key isn't sheared and slightly off.

Jeff Pittel

 

[briggs206]

it surely isn't mint condition. im not sure the model number but its solid state ignition. the owner said it pops after running warmed up. I wonder if its lean. I agree on the roller style self propel. I didn't care for that design either. maybe il pass if the price seems high.

 

[JohnBoy1]

Solid state D600 has coil like the f series. If it starts fine then starts to miss and pop the run side of the coil is bad.

 

[Phototone]

It could also be caused by a build-up of carbon and old fuel deposits in the muffler, which under the intense heat from the exhaust from the cylinder, is igniting.