QuestionI have replaced the carburetor on my Poland blower but still won't crank unless I put some gas into the spark plug hole then it will crank and run if I play with the slow/fast
arm on the carburetor but will still die eventually any ideas?
AnswerGlenn
Although I haven't worked in the field in 15 years, two stroke theory doesn't change much .
Is your high idle (out of gear, unloaded) smooth? It shouldn't be. Two strokes without electronic mixture controls are almost always calibrated to be slightly rich when unloaded, as the nature of all three induction systems (piston port, reed, rotary valve) is such that adding a load leans the effective mixture. Something to do with flow dynamics, I didn't need to know, as I don't design them.
You've covered the common problem area -- ignition. I suspect you have an air leak somewhere. Upper or lower crankshaft seal, reed plate gasket, intake gasket, and upper housing gasket are common areas, in that order.
Mind, this is generic two cycle troubleshooting advice; I don't pretend to know the model you're working with.
To track these things down in the shop, we'd build custom block off plates and pressurize the crankcase to a few inches, then watch the gauge to see the leakage rate. Not terribly practical unless you're rebuilding, but you sometimes found porous castings and cracks that way.
When I'm feeling adventurous I'd spray starting fluid (with a tube nozzle attached) around all the seams with the engine running to see if the run behavior changed. Not recommended; too dangerous.
