FJ1100 recommended carb jetting?

[Antonn3]

Hi, wondering if someone can help out with recommended starting point with jetting on my rebuilt carbs?
I have done a search, but cant see anything similar  with my setup , mostly just later FJ1200 settings.

What the 85 FJ has:
-top end has been rebuilt, as have carbs.. carb diaphragms check out good
-dual Uni-pods
4-2 exhaust with NOS Jardine Cans
- collector custom made  2 into 1 on each side, with a crossover pipe
-elevation is 1600 feet
highest summer temps around 35degrees C (95F) with average of 17degrees C (62F)

Thanks in advance,
Tony

[Antonn3]

no one? 
Thanks,
Tony

[craigo]

Wait for the guys at the WCR to come home. They seem to be the brain trust for the 1100s

CraigO

[Travis398]

No 1100 Love around here at all. 

Richen the bottom and lean the top. I believe 110 main and 40 (bad memory, I may have 42.5)  pilots is what my bike likes.
I believe I left the needle alone, but it is pretty common for people to shim it up (richen) just a little.

I didn't touch the air jet, but that doesn't mean it is right. It just runs good.   

[Antonn3]

Thanks Travis, it looks like you might be close. Here is an old write up I had lost/found a while back on jetting.... the 85 now has 112.5 mains with 40 pilot jets.... so going by this write up .. I could go with 117 mains and 42.5 pilots?


Jetting Recommendations
by Denny Zander

Here is a simple set of jetting guidelines that have worked for me. For those considering jet changes, this might help select a starting point.

1 jet size for custom 4 into 2 exhaust

2 jet sizes for 4 into 1 exhaust

1 jet size for K&N filter (single inside airbox)

1 jet size for drilling out the bottom of the airbox

2 jet sizes for both single K&N and drilled airbox

2 jet sizes for individual filters

2 jet sizes for no muffler (open header)

1 pilot jet size for every 3 main jet size increase

Add up all the jet size increases and subtract one. (Remember they go in steps of 2.5 for each jet size)

Under a mismatch condition, like individual filters and stock exhaust or 4 into 1 header with stock filter and air box, subtract an additional 1 jet size.

Check plug color often, sync carbs after each jet change, make sure the floats are set correctly, and seriously consider purchasing a Color Tune. (See "Color tuning Carburetors" in the Maintenance Section).

Make sure your carbs are in perfect working order before making jet changes.

Example from my '79 XS1100 F:
Stock main jets: 137.5

Stock pilot jets: 42.5

2 sizes for 4:1 exhaust (Jardine)

1 size for single K&N

1 size for drilled air box

4 (main sizes) - 1 = 3 or 137.5 + (2.5 * 3) = 145.0
1 (pilot jet size) or 42.5 + (2.5 * 1) = 45.0

[oldktmdude]

Thanks Travis, it looks like you might be close. Here is an old write up I had lost/found a while back on jetting.... the 85 now has 112.5 mains with 40 pilot jets.... so going by this write up .. I could go with 117 with mains and 42.5 on pilots....

117.5's maybe a bit rich at 1600ft altitude. I think that 115 mains would be closer to the mark. 42.5 pilots could also be a tiny bit rich. I'm running 117.5 mains, 42.5 pilots with adjustable needles set with the clip in the forth position down from the top. Idle mixture screws are set at 2 3/4 turns out.
   My engine has 1219cc Wiseco kit, unipods and V&H four into one exhaust, running mostly at sea level. This seems to be a good combination for my bike but different fuel, riding styles and atmospheric conditions will affect set-ups differently.    Pete.

[Antonn3]

Pete, looks like you might be right, as he doesn't allow for elevation and temp.

Thanks
Tony

[Antonn3]

Hello, well Im finally getting around to starting the bike up after its rebuild
Problem is: when I  start the bike, it will only run with full choke on and if I lessen on the choke it dies?
Mixture screws out at 2 1/2 turns.
Hard to adjust for idle as is.
What should I be looking for, or at least, a starting point?
.....see top of topic for info.

thanks,
Tony

[Antonn3]

BTW.... I ended up putting in:
112.5 main jets
37.5 pilot jets

Tony

[Pat Conlon]

BTW.... I ended up putting in:
112.5 main jets
37.5 pilot jets

Tony

Tony, you have 2 issues:

1) the bike will only run on full choke; your idle circuit is plugged. Gotta pull the carbs and clean them. See the carb files for a complete description on cleaning.

2) in my opinion, your jetting is too lean for the pipe and UniPods you have on your bike. Who told you to run this jetting? It's real close to the stock setting which was lean to begin with...let alone, now even leaner with your mods.
I would suggest 40 pilots and 115 or 117.5 mains with the air/fuel idle screws set to 3 turns out, as a starting point. When the bike gets running, don't forget to sync your carbs....and set your idle to 1000-1100 rpm.
Now do the idle blip test to fine tune your mixture screw settings, Read your plugs, listen for ping, and go from there.

Gotta get your carbs cleaned first.....pay attention to the fuel passage which draws from the bottom of the float bowls and goes up the side to the brass tube....that is easily clogged.

Cheers

[oldktmdude]

Tony, you have 2 issues:

1) the bike will only run on full choke; your idle circuit is plugged. Gotta pull the carbs and clean them. See the carb files for a complete description on cleaning.

2) in my opinion, your jetting is too lean for the pipe and UniPods you have on your bike. Who told you to run this jetting? It's real close to the stock setting which was lean to begin with...let alone, now even leaner with your mods.
I would suggest 40 pilots and 115 or 117.5 mains with the air/fuel idle screws set to 3 turns out, as a starting point. When the bike gets running, don't forget to sync your carbs....and set your idle to 1000-1100 rpm.
Now do the idle blip test to fine tune your mixture screw settings, Read your plugs, listen for ping, and go from there.

Gotta get your carbs cleaned first.....pay attention to the fuel passage which draws from the bottom of the float bowls and goes up the side to the brass tube....that is easily clogged.

Cheers

Tony, I think Pat's advice is spot on the money. You are too lean. Clean the choke passages as suggested and go to the jet sizes that have already been recommended. People here know what they are talking about, listen to them!  Pete.

[Antonn3]

thanks guys. the carbs have been cleaned thru and thru with attention paid to make sure they were very clean.
As for the jets ..Randy helped with selecting the combination.
Keep in mind this is a Canadian FJ, which had different jets if I recall?

Thanks
Tony

[Antonn3]

Ok, now that I found Randy's old email on the jet selection, he does state I might have to shim the needles.

Tony

[Alf]

Hola

I agree with Pat. I would fit 117,5 main, 40 pilot jets, and leave float bowl height at minimum and I would increase pilot air jets one size to help driveability around 2.500 rpm. And perform the procedure to set the mixture screws settings, starting from 2 1/2 turns out. I would test these settings with the needle in std position. The std emulsion tubes must be oval with the time & use and the bike is running rich. I think you don´t need to shim the needle

If you fancy, take a look at my web where I describe the carb tests that I perform, subtly different and that my friends and myself have development with the time & experience

Keep us informed, please
Regards

Alf

[Alf]

Sorry, I wanted to say leaving the float bowls level LEAN, so the opposite:  at HIGHest level