EDB-Old Magnet. Will check out the mag cap:eek: The plugs are old champion N1 or something. Have changed them from another head two sets same thing.As for the failure in the orignal head could not tell as it had been run some after it came off.[Needed to load to get to new home] Both the stem and head were peened real good top of piston gone.

edb-Old Magnet Question after checking out the other items my brain went in gear[very rare] . Could it be that i don't have the fuel pump connected not getting enough fuel.[has never ben connected] It just has gravity flow and allway worked ok.
catrat

Hey, what have you got to lose......hook it up and see. A leaned out mixture will cause the engine to stumble and backfire. It's the simple basic things that drive ya nuts:D

Old Magnet -SJ -CC -edb Thanks for all the ideas and sugestions. Have finaly got the 3400 engine running some what good. I belive it was a combination of items. I think the bigest problem was that the high speed jet would turn its self in while i was runing it. It is still smokeing quite a lot. Hope to get to work it and seat them rings;) I have also tryed something i had wondered about on it. I have mixed gasoline with fuel oil 50-50 it runs ok on it power appears good and still starts easy. Gas here is 3.00 fuel is 2.29 off road. Thanks again
catrat

Hi catrat,
one thing I was taught about troubleshooting in my early days was to fix the easiest first most obvious problem and keep at it until what seemed to be a big problem is usually gone. I applied this throughout my career and it never failed me. Usually by the time I got involved many others had been and not achieved much as they were addressing what was the big picture problem, which was the result of the combination of many small problems, fix the small problems and the big one is usually gone at the end of the day.
In your case here you have started checking the easy things, carried out a mag. and carby tuneup and now the unit is responding without redoing the valve job!! It was probably these things that caused the initial valve failure, it leaned out and bang. So now you are addressing the initial root cause of the failure and not just repairing the result. Well done and keep at it.
Cheers,
Eddie B.