Ironhead Carb or Timing Issue?

CourtHouseCustom · #1 1st May 2008

Hey all, just did a re-build on an 80 and fired it up yesterday. The bike will idle with the choke all the way engaged but as soon as you touch the choke or hit the throttle it dies. It looks like a lot of fuel is squirting out when you hit the throttle, almost too much. I have adjusted the idle mixture screw still with same results. The motor is a fresh re-build with new over sized pistons, rings, valve job and electronic ignition. The carb was also re-built with a new seal kit. Any suggestions?

BuckIRyder · #2 1st May 2008

What brand carb? Accelerator pump set too high? Gaskets didn't shift during reassembly? Everything tight?No air leaks? Checked the timing with a light? Some stuff to start looking at.

CourtHouseCustom · #3 1st May 2008

Thanks, I'm still working on it. It is the old Keihin Carb, not for an 80 model it is the older one......76-78 maybe. I have everything to check the timing but I haven't been able to keep it running long enough. I will check the other things and hopefully the timing in the next few hours.

Thanks-a-lot, D.J.

jagdprcp · #4 1st May 2008

Defiantely check for intake leaks. The WD-40 trick will work for large leaks, which sounds like you have.

Will the bike continue to idle if you don't touch the enrichner or throttle? It could just be that it needs to warm up a bit....

CourtHouseCustom · #5 1st May 2008

Quote:

Originally Posted by jagdprcp

Defiantely check for intake leaks. The WD-40 trick will work for large leaks, which sounds like you have.

Will the bike continue to idle if you don't touch the enrichner or throttle? It could just be that it needs to warm up a bit....

I don't think there is any intake leaks, I used new gaskets and rubbers on the manifold. Yes, the bike will idle fine with the choke engaged. It dies as soon as you touch the choke knob or throttle. This happens no matter how long I let it warm up.

I also cleaned the idle mixture screw hole to be sure there was nothing clogging it.

I will check for intake leaks and keep trying.

Thanks, D.J.

-stinky- · #6 1st May 2008

What jets are you running? When the choke is engaged you are richening the mixture. When you disengage the choke it leans the mixture out. Your pilot jet may be too small and when you disengage the choke it leans out too much and dies.

jagdprcp · #7 1st May 2008

Check your float level as well. Jetting could be off also. How many turns out is the Idle Mixture Screw?

New gaskets and rubbers don't always mean no intake leaks. If one just happens to slide during assembly you will have an intake leak. It does sound like you might have one though.

CourtHouseCustom · #8 1st May 2008

Well, I checked for intake leaks with WD and found nothing. Also, the bike idles higher as you open the choke.......just the opposite of what it should do. It's got me baffled.

I have the idle mixture screw about 1 1/2 turns out.

Also, I have not changed the jets. It is set up just like it was before the motor re-build and it was running before that. The only thing different is the carb re-build kit which was only seals, gaskets, slow jet plug and a new float needle.

Thanks, D.J.

bulletbob · #9 1st May 2008

I have about the same thing going on.The shop set my cams and installed the new Crane Hi-4.Cleaned and rebuilt the carb (my carb).The bike will start first kick every time but runs about 2or3 seconds and dies.
I keep saying carb and they keep saying can't be.
All the basics have been tested over and over.Timing right,no leaks,has to be carb.I think.
Good luck
Bulletbob

CourtHouseCustom · #10 1st May 2008

Quote:

Originally Posted by bulletbob

I have about the same thing going on.The shop set my cams and installed the new Crane Hi-4.Cleaned and rebuilt the carb (my carb).The bike will start first kick every time but runs about 2or3 seconds and dies.
I keep saying carb and they keep saying can't be.
All the basics have been tested over and over.Timing right,no leaks,has to be carb.I think.
Good luck
Bulletbob

Yeah, that's pretty similar to what I have going on. I have tried everything I can think of with the carb. I am trying mine without the air cleaner on it and the inside of the carb throat is getting REALLY wet with fuel. I just don't understand why it is acting WAY worse after re-building it.