OK need a bit of help here. Have a 1986 Heritage which was imported to the UK from the states. It is very original with the plug in the Carb to prevent "tuning" the mixture screw. It's coughing very badly when the revs increase and running very lean (white deposit on plugs) we are wondering if the main jet should go up to enrich the mixture it currently has a 170 main jet. Are they easy enough to find for this year carb.

 

Could be the compliance fittings ,manifold to head. Definitely pull plug to access mixture screw and increase low speed jet 1 to 2 sizes. Main jet is pretty close from factory ,you would have to do a high speed run test to check main.

 

My money is on "intake gaskets" !!!!!! And agree to pull the plug for adjustment ONLY.

 

It's NOT the main jet. As stated, check the compliance fittings, they are probably leaking.
That said, there's nothing you can do to that carb to make the bike run perfect, it's just a lousy carb. Switch it out to a later CV, S&S or Mikuni carb, that'll wake that old EVO up.

 

X2. Intake leak for sure. Todd

 

I had a EVO powered stock carbed Heritage back in the '90's if I remember right, just drill a little hole into that plug and then pull it out with a spring hook or pry it out. It's blocking the low speed fuel mixture screw, turning the low speed mixture screw counter clockwise will richen your low speed fuel mixture. The main jet is for high speed fuel mixture (4000-5000 RPM). You won't need to change the main jet. You can also adjust the needle it affects the mid range. I think lowering it richens the mixture. If I remember right??? Their's probably good videos on youtube.

 

Raising the needle richens the mixture, lowering the needle leans the mixture

 

Hello old chap, from just up the road and welcome to HDF! I suspect you have other problems, as suggested above, so leave messing with the carb settings for now. If you remove the carb to check it over, buy a refurb kit, which comes with all gaskets and rubber parts etc.

For a useful source of parts diagrams and info try this website.

 

Hi Everyone and thanks for useful suggestions. We took the carb apart for ultrasonic clean. All seems good within the carb. Checked all gaskets and again all looked good. Will check our work again. Is there a seal for the Fast idle Cam (compliance fitting)? I don't think we took that bit off.
Wondering if to upgrade to the later CV version… although I would like to keep the bike original if i can.

 

Since you have the carb off I would change the intake seals and compliance fitting.

While I've never had a butterfly carb many here have said that the CV is a much better carb.