HELP tuning mikuni 44

[DATSUN671]

i have a recently rebuilt l20b bottom to top. my only problem is tuning the mikuni 44. it runs fine when its cold but when it starts to run on normal temp it bogs out then runs good and it also feels kinda weak.

 

thanks for the help.

[DATSUN671]

also i checked the exhaust temp #1 is 400 degrees #2 is 500 #3 is 600 and #4 is 500

[banzai510(hainz)]

is this a 1 carb or dual carb set up?

[Stoffregen Motorsports]

The most overlooked area of a dual carb setup is the linkage. If the throttle stops are not set up properly you can twist a throttle shaft which may have the symptoms you describe. You can straighten them out, but be careful. There is a dual carb linkage thread around here somewhere that has some good info.

 

For the record, I really do not like the mechanical style linkage with the two pushrods, centerpull is the only way to go.

 

Also, a bog in the middle range could be lean or rich. It's best to supplement the symptom with a visual inspection of the spark plugs before making any jetting changes.

[DATSUN671]

I found 2 fuel lines that go from the tank to the motor. One is for the carbs and the other idk it was just cap off. When I pulled off the cap on the fuel line there was fuel coming out. Could this be the return line?

 

Does anyone have a photo of the whole fuel system?

 

Thanks for the help

[_chiefjt]

Yeah that's probably the return line. Also, have you had the carbs synchronized?

[Stoffregen Motorsports]

 Also, have you had the carbs synchronized?

I guess that's what I was going after. If the carbs won't synch up properly, then it's likely there is a bent throttle shaft.

[DATSUN671]

Also took the carb out to see if they will spray and only one side was spraying fuel. What could be the cause of this?

[shacks510]

Pull the jets out and look inside the jet hole and see if there's gas in it. It'll be clearly visible. Also squirt the jets with carb cleaner and make sure all holes flow good.