4-1 filter,pipes and jetts

[chevy45412001]

I did not want to step on winter hawks thread to much. I have 4-1 kerker (no baffle) ,4 individual pods (no name brand ). Heres the story,Pipe was on frm PO. I removed stock air box and installed filters. After filt chang bike lost a ton of midrange arm jerking power. No guts after 5,500 rpm. I put a washer under needle to raise it. That helped a lot in mid range. Went from stock 112.5 jet to 125.0 then up to a 155.0 main jet. 155 way to big would not run at all above 45mph. dropped down to a 137.5 main. Now runs real good. will take in XSess of 9,500 rpm's ,Now in all this i have never turned a screw or chganged any other jets.What if any diff,would air piolet jets do or not do. and the number of turns of same in or out. Or should i leave well enough alone?I do think i'm going down 2 more jets to a 135.0 as my plugs still look a lilttle black.Any layman help here would be appreciated.Btw i have the back fire at let off of throttle (doesn't bother me ) and a small tick just off idle till 2750-3000 rpm (but that seems to be the norm for all i've read here ) tia

[Dennyz]

Judging from the jets your are using, you have the second generation XS carbs ('80-'81). With the exhaust and filters you are running, the 137.5 are close. I would bet you could go down to 132.5s and sill run strong, yet bring the mileage up. I prefer to run a little to the lean side. The second generation carbs usually don't need to have their pilot jets increased. Adjusting the idle mixture will improve the idle smoothness, off-idle transistion, and starting. The best tool for the is a Color-Tune.

[prometheus578]

Denny, I've seen Color Tune mentioned in several other posts but after searching the web can't seem to find any info on how it operates, nor availability and prices. (My plugs are clean, but geez... the exhaust smells like it's running rich.) Any place local that I can pick one up? Approx. price?

[Dennyz]

I purchaced my Color Tune years ago from the Internet (don't remember the price). I will see if I can find a link.

[TopCatGr58]

Hey Denny, and Prometheus,

Found this one:
Auto Expert Products

Another:Gunson Auto Test Equipment

Hope this helps, they are around $59.95. T.C.

[Dennyz]

here is another one:

Color Tune

Color Tune "How To"

[chevy45412001]

sorry

I've got later carbs than that Denny z,I ride the XJ maxim version of the great XS series. As for starting i hit choke hit key wait aprox. 15 seconds take off choke and ride.

[Dennyz]

I have never worked on XJ carbs, but I understand they are very similar to the '80-'81 carbs. The only real difference is the port that joins all four together. I have read where some have plugged this port when tuning the idle mixture. Mike Hart had a drawing of the home made plug tool

I've got later carbs than that Denny z,I ride the XJ maxim version of the great XS series.