95 600 diversion, cant get no1 cylinder running right

Hi All I hope someone can help as I am literally pulling my hair out

My divvy has been running badly for a long time and I have got everything else sweet apart from no1 cylinder, using colour tune I can either run it rich and have it fire every time or run it dark blue and it starts missing, I have balanced as best I can with it running as it is, fully and very carefully cleaned the carbs, set the floats spot on, compression is 7 bar across all 4, valve clearances were corrected 6 months ago, have swapped plugs and coils over and even carb guts and it is consistently running badly on 1, any thoughts.

 

How are the carb to engine rubber boots? If they start to dry up they'll crack and allow air to get in.

 

Yeah you're sucking air.

Try dousing the boot at the head with WD-40 while it idles. In particular make sure you spray upwards at the bottom and along the inboard side...from my experience the gaskets seem to fall apart starting at the bottom, and if you don't spray directly at it, it may not find it's way to the leak just running down...the OE gaskets are very narrow circles around the port, not the same size as the boot diameter...so you actually have to be spraying straight into the leaking area to get a reaction...

Idle will react and the motor will pick up and smooth out momentarily as it stops the air leak...

Make sure the vac cap on that one's not shot too...

 

Thanks, the boots are new and high temp siliconed as that was certainly an issue, I have sprayed with wd40 and it doesnt affect the revs, it used to but since the sealer it doesnt,

why might it only run when rich, ie a yellow flame but misses when i try to lean it off to blue, for information the burn starts to go blue at about 4 turns on the idle screw when factory should be 2 ish, the other 3 cylinders are between 2 and 3 turns and running dark blue and dont miss

 

How many MILES does 6 months equal?

Is the recommended interval 5K, like the earlier "airheads?"

That being said, it's probably a bad throttle shaft seal. REALLY hard to detect as a vacuum leak, but that's probably what it is, based on everything else you've checked.