Issue about vapor or smoke through the carb.
A 7hp Tecumseh L-head went to half speed while clearing and could not be throttled higher. The engine was in parts when I got it so I can only go by reports about that. I thought it might be carb related so went through the carb. These was gas in the float so I put the head back on and fired it up.
It still only ran to half throttle. Seems to run somewhat well at half speed and lower but does sound not “usual”. There seems to be an extra snap sound (non-metal) which I think is coming out of the carb but not sure. It could be from the muffler.
There is either smoke or vapor out of the carb. Not a lot and disburses quickly. I thought it could be timing causing the intake to not be closing fully. The engine has solid state ignition so I thought it might be a broken flywheel key. Pulled the flywheel and the key is fine.
It seems to be the intake is not seating fully. What I don’t understand is how can that happen instantly. The machine has run well through the prior storms and in the middle of the last storm it went to half throttle. I was told it was spitting gas out of the throat but what I see is vapor or smoke. It’s not much or a strong flow.
The valves are at .008 intake and .010 exhaust. The spec is 8 and 12. The next move is to lap the valves. If that does not cure it then possibly there’s a crack somewhere in the head under the valve head. ?? Anyone ever have something like this or suggestions if not seat or wall crack??
If a valve problem is it usual for it to show itself all of a sudden?
This message was modified Feb 10, 2011 by trouts2
