Hi there. I have a 1985 Harley Davidson Iron Head Sportster 1000 that I am trying to get running good again. I am a Harley technician but I'm more familiar with the late model Harley's. I have tested and changed a few things on it. I installed a late model CV carburetor (not to solve the issue, but to make it run better). Seems to start great when cold. Takes about 5 minutes to warm up. I take it down the road and runs great. I return to my shop and it will hold an idle just fine. I then shut the bike off and let sit for a few minutes... then try to start it back up. It starts with a little help from accelerator pump, but will not hold and idle unless it is run again for a few minutes down the road or the choke is out. The points gap it good. New plugs and wires. Fuel tank and screen are clean. The jets are 175/45 with a perfectly clean carburetor. Intake seals and inlet boot do not leak. The compression is around 90PSI. I feel is a little low but im hearing this is normal. I want to get this thing going but I'm lost with it not holding and idle after it is restarted hot from a 5 minute rest... Please help? I feel like I'm missing something...

 

I'd try adjusting the carb to run a little richer and maybe going one heat range hotter on the plugs

 

Welcome to the world of Ironheads!

 

If the gas line is too close to the heads it could be a vapor lock situation