Stovebolt engines that sit idle for a long time are really bad about getting sticky valves. That's particularly true if gasoline is added to a fuel tank that has been sitting empty for years. Gum, varnish, and other byproducts of fuel that has evaporated are suddenly dissolved and ends up causing valves to stick in their guides. Be sure you're using fresh gas from a clean temporary tank for the initial startup and run-in, and clean or replace the vehicle's fuel tank before trying to use it. Soaking the valve guides from the top with a penetrating oil such as KROIL, PB Blaster, spray carburetor cleaner, or whatever similar product might be available to you is a good idea, but the only sure fix for sticky valves is a cylinder head rebuild- - - -that consists of regrinding the valves and seats, and cleaning out any sticky deposits in the valve guides.
Jerry
Thanks for your answer. I was also thinking it could be a sticky valve. But i removed the valvecover and inspected the head when running and it looks like all the valves move as they should. I have done the mistake by filling the gas tank with fresh gas but using a filter between pump and carb, maybe that helps?. I ran fresh fuel out of a can the very first time i started it and it was the same. Can it act like this if the carb needs cleaning or is it only valve sticking or ignition timing it could be?
