Carborator; Weber IDF or EMPI HPMX Jetting

No two "Identical" engines respond exactly the same to a given set of carb jets.....   That said, your best course is to buy C. B. Perf's  Weber Manual....   It will explain just about everything and Danny Piperato can fill in the blanks.....   When you get your manual, read it cover to cover at least twice....   Good luck and hope you solve the problem...

Bluespeedster (sounds so impersonal. Do you have a first name?)-

Any chart is only a starting point, and will usually err on the rich side, as no one wants you coming back looking for a replacement for a seized engine from running too lean on their recommendations. And Leon's first statement is right; you and your buddy can build what seems like identical engines and they probably won't use exactly the same jetting. It'll be a trial and error thing; change one thing at a time and see how it reacts. From what I remember, a .60 idle jet seems large for your 1600, so start with the idle circuit. Go one step leaner, retune and see how it runs. If you can find someone close by with a selection of jets it will help, otherwise you'll end up with a collection of your own (and the investment that goes with it).

Don't let plug color be the final say; as Leon said in your sooty plugs thread, proper plug reading requires a full throttle run through the gears and immediate shut off to be effective, and today's gas is much harder to read. Rely more on how the engine runs after you make a change. Hope this helps. Al 

And as Leon said, get CB's Weber manual. There are some things in it that could be better, but the troubleshooting section is totally worth it.

Leon- I will look for the manual; thank you for the lead. And yes understand there are no 2

         endgines alike. Just need a bench mark to start.

ALB- sorry for the inpersonal approach, need to remember to put my name at the end of a

        posting. Thank you for the not on lean/rich levels to keep the motor running properly.

        My understanding is; and based on many factors one being just as you mentioned gas

        quality, it a good idea to opperate just above Stoichiometric ratio for air cooled

        engines. There is alot more to be said about this but I'm not going there for its still a

        fog how one measures A/V ratio without an expensive analyizer. I'll drop down to

        a .50mm idle jet and see what happens.  Thanx again, Michael

I'm assuming you have dual carburetors? Lots of good info in the Knowledge section:

https://www.speedsterowners.com/forum/knowledgebase