No/slow acceleration. No top end.

[GilHirien]

Hey all. First, Thanks for the wealth of knowledge and support already on these forums and all the contributors. I have spent hours pouring over all kinds of topics on this site which were informative, helpful, and also gracious when user error was discovered.

Secondly, on to the problem at hand. I have had my GZ for 2 years. It ran for most of 1. Finances always being very limited, it sat for about a year with little progress made. I ended up having to replace my crankcase due to other problems and now all is reassembled. Those issues have been resolved leaving a newly discovered one. I have no top end power at all. Timing is dead on; I followed the maintenance procedure to the letter when reassembling everything. I have adjusted valves back to spec. They were horrendously tight and not sealing. No gap at all. Intake has been set to .008 and exhaust to .012. Piston was at TDC on compression stroke. Many thanks to the great instructions found in other threads for this. I did a compression test which yielded 180 peak psi which is solidly within normal operating range (140-199) though I will test again as I don't think it was quite warmed up enough.

It will crank right up with a little choke and seems to handle throttle just fine in neutral. It does not want to run without choke but can be coaxed along slowly, but starts running badly or at least inconsistently and may or may not cut off. If I turn the idle adjustment to increase the idle as far as it will turn, it will run with no choke at all without cutting off, but badly (roughly the same as it is with half choke and normal idle speed).

Out of neutral it will pull with no throttle to maybe 1/4 throttle but pretty weakly. It does better with more choke. It will pull a tad harder, but still will not increase past 1/4 throttle. If I give it more throttle than that it will start sputtering and lose torque, and when throttle is released it will backfire, pick back up slightly and resume running at no throttle to 1/4. It does this in first and second gear. It will not take any throttle at all in 3rd or above, and will not pull at all in 3rd or above. I cannot maintain 25 mph in 3rd on mostly flat ground.

To me this sounds like fuel delivery problems. The tank sat with very little gas for a very long time. Bad gas was purged and replaced with new gas and seafoam (3 oz. or so). There was a good deal of crud in the tank, petcock, fuel line and carb when I first tried to start it after reassembly. Petcock was removed and cleaned. Fuel line was likewise. Carb was pulled, opened up, and cleaned to the best of my current ability. No inline filter yet but working on it. I thought that I cleaned it pretty well when I had it off before, but it may need more thorough work beyond my current skill set.

Thoughts, comments, observations, suggestions, pointing and laughing (as long as it includes the previous as well) are all welcome.