Zenoah G38 and G62 same problem
 

My father and I have a P-40 with a G38 and a P-47 with a G62. We got the G38 used in the plane, looks new. Tried running it and would only pop and run strange for about 2 seconds(kind of a dieseling noise) then die. We've spent hours tweaking it and trying to get it to run, new gas, new oil, new plug, has spark, no go.
So we gave up, and switched to our P-47 that has a brand new Bennet Built G62 on it. We went to run it, and it started on the 2nd flip and ran beautifully through that first break in tank. We took it down to the field, and to our amazement, it is now doing the exact same thing as the G38. We have tried literally everything we can think of, and no go. Will pop sometimes, will not run. Have tried again, new gas, new oil 50:1 mixed 50:1, new plugs, cleaned needles, different settings, nothing makes any difference. We ran the fuel in our US41 just to make sure it worked, and it ran beautifully.
We have no idea what else to try. Does this sound familiar to anyone? Any ideas? Thanks!

RE: Zenoah G38 and G62 same problem
 

Spark compression fuel, If you are missing one of the three it don't go. Is the pump drawing fuel? It's easy to get the fuel lines hooked up wrong. Check the plumbing.

RE: Zenoah G38 and G62 same problem
 

Yeah, it seems to pump well. We can prime it and get fuel to come out the carb, wet finger. Then we try and start it for 5 minutes, no luck, pull the plug, and it has fuel on it. Not a lot, looks like the right amount. Compression is great. Check spark when plug is out, bright blue spark. No clue...

RE: Zenoah G38 and G62 same problem
 

Make sure the flywheel, containing the magnet, hasn't moved. A friend of mine had a 38 that would only pop.

When we investigated further we found that the Woodruff key on the crankshaft had sheared. This allowed the flywheel to move slightly on the crankshaft and hence put the timing of the spark out slightly.

Hope this helps

Colin

RE: Zenoah G38 and G62 same problem
 

We are now thinking that the problem must be something like this. Maybe we are using a bad flipping technique that caused this on both of our engines. Thanks for the help, we will investigate.

RE: Zenoah G38 and G62 same problem
 

Hi I have a problems with the oil mixing , in the manual they say the enigine works with 25:1 ratio but in other place have read that the engine works with 32:1 ratio. Can some help me!!!

Charlie

RE: Zenoah G38 and G62 same problem
 

I don't think it will make a lot of difference what you use.
I would go with the manual. Who knows more about the engine than the people that made it?