Dong Fang DF 250 RTB Bobber Information

[Roadkill]

its a 2 valve pushrod, everything it has is between 2500-5000 rpm , if u drag out more rpms great 4 u beating the soft springs I was givin , if u don't here your valves clicking away , either you geared to low or to tight

and tight = engine death

redline all u want , valve float from pushrod engines stops any poss damage

unless valves to tight ---

and roadkill , that "miss" sounds like u need a valve, like axa but not blown cylinder like him

adjust valves NOW

Thanks! I started the tune over. Valves to .002 and .004, new irrudium plug gapped to .028, raised jet needle (Mikuni carb) to top position, adjusted fuel/air. She runs great now with a slight miss if I run at low rpm for a while. I think that the carb might be a tad rich. I would like to check the compression both cold and warm, but can't find any info on compression range in PSI.

Just did a quick search and found that depending on the cam setup, compression in psi should be between 15-20 times the compression ratio. Interesting for me but not much help as I still don't have a baseline to tell if a valve is causing problems or an exact compression ratio. If I go with 9.02 then I'm looking at 135-180psi on a good engine.

Maybe I'm looking at this wrong. If I have a bad valve, it will be way lower than this range or won't hold pressure very long and I can look at as a very rough leak-down test

As to gearing and RPM. I date back to when 6K was very high RPM and torque was king. I still feel like only Dremmel tools and turbines should turn 12K. Remember when the powerband for deisels was 1750 to 2150 RPM? I'm running stock front sprocket and 35T rear.