Ironhead Need Some Clarifacation/Carb or Clutch

MegaDON · #1 24th October 2011

I have a 1973 XLCH 38mm Mikuni, Streight Pipes, .060 Pistons.
I have been having clutch/Carb problems. I just soaked the carb and finally got her to idle correctly and did a clutch adjustment. so I started the bike, warmed her up and was going for a ride to free up the clutch plates. I have my brother push me and ger het into gear, here is were I can use a little direction. I believe is its a carb issue, I give the bike some throttle and it feels like its going to stall. But when its at idle (nuetral) it revs nicely. Could it be the clutch slipping? Or do I need to go up a jet size or adjust the carb again (carb has factory jetting)

runingmouse · #2 24th October 2011

Quote:

Originally Posted by MegaDON

so I started the bike, warmed her up and was going for a ride to free up the clutch plates.

Hmm never heard of this way for this. The way I did mine was to disasemble and cleen them.

But to answer your question. There has been many simaler questions on here about use of straight pipes. The main jet usualy has to be a biger jet then stock. So if these are new pipes. The carb neads to be set up. My guess.

alanbt · #3 24th October 2011

How do your plugs look? What are you getting for compression, wet and dry on both cylinders?

MegaDON · #4 24th October 2011

Plugs are a black and a little wet, compression is 140 and 135, dry with no oil added into the cylinders.

piniongear · #5 25th October 2011

Quote:

Originally Posted by MegaDON

I have a 1973 XLCH 38mm Mikuni, Streight Pipes, .060 Pistons.
I have been having clutch/Carb problems. I just soaked the carb and finally got her to idle correctly and did a clutch adjustment. so I started the bike, warmed her up and was going for a ride to free up the clutch plates. I have my brother push me and ger het into gear, here is were I can use a little direction. I believe is its a carb issue, I give the bike some throttle and it feels like its going to stall. But when its at idle (nuetral) it revs nicely. Could it be the clutch slipping? Or do I need to go up a jet size or adjust the carb again (carb has factory jetting)

Did you ride off with a cold engine and then give it some throttle to get it going? From your description it sure sounds like that is the case.
Start the engine and warm it up for a couple minutes before pushing it down the drive to free up the clutch and shoot the throttle to it. A cold engine does not run well.

If your Mikuni is clean, the clip is sitting in the middle notch on the needle, and you have the standard jets in it your carb IS NOT the problem.
I assume you know how to adjust the air screw on the Mikuni?
Turning it in enriches the mixture and turning it out leans the mixture.
pg

MegaDON · #6 25th October 2011

After the 2 nights in Pinesol and compressed air/carb Cleaner, the carb is clean (it also would not idle before the cleaning) The needle jet is also positioned correctly.

The way i tuned the carb was I warmed up the bike(2.5 turns out to start), then when it idled i raised it a bit using the idle screw, then turned the air screw in until the motor would "stall" then turn it out until it almost "stall" then meet in the middle of those turns. Thinking about it, the motor might not have warmed up fully. Ill give it a try and post the results, Thanks everyone.

piniongear · #7 25th October 2011

Yes, by all means let the engine warm up to operating temperature, then do the carb adjustment.
We will be waiting to hear the results.
pg

scottfisher · #8 25th October 2011

Quote:

Originally Posted by piniongear

Yes, by all means let the engine warm up to operating temperature, then do the carb adjustment.
We will be waiting to hear the results.
pg

+1

It is getting cold in Canada and my my bike is hic-cupping, and farting like a nut until it gets warm....then it purrrrrs.

s

MegaDON · #9 28th October 2011

Had a chance to ride last night, Started her up and did another carb adjustment when she got warm. She stumbles with in 1/4 Throttle, and responds ok after that. Got back to the garage and cleaned the jets with carb cleaner and compressed air(it still looked clean) and no difference. Should I move the clip on the needle jet down? (fourth position from the top)

piniongear · #10 29th October 2011

Quote:

Originally Posted by MegaDON

Had a chance to ride last night, Started her up and did another carb adjustment when she got warm. She stumbles with in 1/4 Throttle, and responds ok after that. Got back to the garage and cleaned the jets with carb cleaner and compressed air(it still looked clean) and no difference. Should I move the clip on the needle jet down? (fourth position from the top)

Megadon.....
I would say do not move the clip position on the needle.

The reason I say that is because the jet needle (and it's jet) come into play only when you reach 1/4 throttle and on up to 3/4 throttle.
The needle jet comes into play at 1/3 throttle up to wide open throttle.
The main jet and the air jet take effect at a bit above 1/2 throttle on up to wide open.

So what is in play below 1/4 throttle?...... you are asking.
The answer is the pilot air screw and jet are what control
the carb between zero and 1/4 throttle.

So all I can offer is to check the air screw adjustment and make sure the air jet is open and clear.
Since I can offer no other solution you may want to move the needle clip one notch up or down, but I cannot say which way might improve things.
If you drop the clip down one notch this will richen the mixture and raising the clip one notch will lean out the mixture.

So just try it both ways and see if that makes a difference.
The jet needle begins operation at 1/4 throttle and you say it clears out at 1/4 throttle, so I don't have much hope moving the needle clip will help but it is certainly worth trying.
Let me know what it does moving the clip both up and down, should you decide to try that.
pg