Carb jetting recommendation FJ 1100

[balky1]

Hi guys,

I need an advice. I have the carbs on the bench and looking what jets are in:
air: 160
pilot 40
main 105.

Bike has air box and stock exhaust, stock needles. Ran fine, I have the carbs dismantled to change O-rings and joints, but it is a good opportunity to change the jetting also if needed.
Summers here get hot, to around 35-40 °C. Most of my riding is between 0 and 500 m above sea level, but I do at least one trip per year to altitudes between 2000-2500 m.
What jetting would you recommend? I think those mains should be larger, but rode just fine.

[Bones]

I'm in Australia where it also has high temperatures, it's our last month of summer at the moment and can't wait for cooler weather to come along. Can't remember what my air jet is but I'm running 42.5 pilots and up'd my main jet to 120 and it goes like a cut cat. I think standard size main is around 110 so yours sound a bit small. Edit: just read yours is an 1100 so not sure if they were the same as the 1200.

[Pat Conlon]

Runs fine? Why change? Keep what you have....
...or go the minimum, keep the #40 pilots, bump the main to 110 or 112.5 and call it a day.
If you ever lose the air box (UniPods) just shim the needles 1/2 step.
If you also put a pipe on and ignition advance, go with 42.5 pilots, 117.5 or 120 mains. 1 full notch up on the needles.

Experiment, see what you like.

[RPM - Robert]

Sounds like you have a restricted model. I built a few XJR that had very small main jets and different main jet needles in order to reduce hp. If changing jetting you will likely need to change the main jet needle and also make sure you have the "unrestricted" intakes.

[balky1]

Thanks guys.
Yeah, I'll try 110 mains to see where it gets me.
It was a restricted model from Switzerland, restricted to 100 HP. I already have the new carb joints from RPM. I suppose those mains are a part of it. But, like Pat said and what I was also thinking, if the bike ran fine don't fiddle too much, right?

[balky1]

BTW, are those aftermarket paper float bowl gaskets any good? I have 4 new ones sitting around.

[fj1289]

Thanks guys.
Yeah, I'll try 110 mains to see where it gets me.
It was a restricted model from Switzerland, restricted to 100 HP. I already have the new carb joints from RPM. I suppose those mains are a part of it. But, like Pat said and what I was also thinking, if the bike ran fine don't fiddle too much, right?

I'd give jetting a shot - there can be a big difference between a bike that runs "well" and a bike that runs "right"!  The old phrase "the best you have ridden is the best you know" - you won't know if it can be better or not unless you try...

[balky1]

Thanks guys.
Yeah, I'll try 110 mains to see where it gets me.
It was a restricted model from Switzerland, restricted to 100 HP. I already have the new carb joints from RPM. I suppose those mains are a part of it. But, like Pat said and what I was also thinking, if the bike ran fine don't fiddle too much, right?

I'd give jetting a shot - there can be a big difference between a bike that runs "well" and a bike that runs "right"!  The old phrase "the best you have ridden is the best you know" - you won't know if it can be better or not unless you try...

That is my reasoning as well. Will try it.

[RPM - Robert]

Pop up a pic of the main jet needle as well. Maybe see if there is any marking on them.

[balky1]

Pop up a pic of the main jet needle as well. Maybe see if there is any marking on them.

Where are the markings usually located? Do I need to separate it from the diaphragm to see it?

[RPM - Robert]

Mikuni marks them close to the top where the c clip is

[balky1]

Pop up a pic of the main jet needle as well. Maybe see if there is any marking on them.

Needle markings: 5FZ62, clip in the middle of 5 positions.

[RPM - Robert]

The 1100 are marked 5FZ63 in the states and the 1200 is 5FZ72 so I can't confirm the needle. If it just an adjustable 1100 needle with flat bottom slides. We usually end up around a 117.5 main jet and the needle shimmed up.

[balky1]

This is a Swiss model so I expected something different. They don't look to be ever touched by anyone. They are flat bottom slides, yes. As per instructions from this thread, I've put 110 mains (were 105) and left the needles in middle position from 5 slots.

[Pat Conlon]

Did you remove the restricted carb manifolds?