'84 FJ1100 resto mod

[RPM - Robert]

Snap a photo of the emulsion tube. If it is non shrouded you need the shrouded 1200 version as those slides are late late 85 1100s or 1200 slides. The main jet needle needs to be measured from tip to tip as well as the 1100 needles were shorter and the slide had a flat bottom.

[stou]

Here's a photo of both carb parts. The one I use is the one on the right, it has #110 main jet. The one on the left has the #124 main jet.

[RPM - Robert]

The parts on the left are early FJ1100. The parts on the right are late 1100 & FJ1200.

That looks like a curve bottom slide needle on the flat bottom slide as well. You will need to slide the plastic piece off the needles and see if there is a number stamped at the top.

Either way, you are most likely going to have to update to the later parts to make them the same since the flat bottom slide are obsolete and harder to find than rocking horse dung.

Time to break them all down and see what you have. Take photos of the springs and measure the big hole in the bottom of the slide to see if they have been drilled out too.

[stou]

Maybe my explanation was not clear. I have 2 sets of carburetors (2x4). The set on the right are the one that I installed on the bike. The other set came from another bike I have for parts. I don't plan to use the carburetors with the flat bottom. I was just looking for the jets to see if I need to buy 4 new 117.5 to go with the pods filters, like Pat suggested.

[RPM - Robert]

Oh. Since the curved bottom slide carbs have aftermarket jets, you still need to check the needle for number to see if Mikuni of aftermarket.

[stou]

The number on the needle is: 5FZ74. On the needle of the flat bottom slide, there's nothing, no number.

Why did you wrote that the curve bottom slide carb have aftermarket jet? Because they have #110 jets or because of the size? The flat bottom one that has #124 jets.

Left: #124 from flat bottom slide. Right: #110 from curve bottom slide.

[RPM - Robert]

sorry, this two different sets is throwing me off.

The needle with no marking in the flat bottom with the 124 appears to be a 1200 aftermarket kit someone stuck in a set of 1100 carbs.

The other needle marked 5FZ74 is a Yamaha/Mikuni needle and the main jet at 110 is stock.

[stou]

Good, so I used the good carburetors. I'll make a list of parts I need and I'll probably made my RPM order this week. Thanks Robert!

[Dieselman7.3]

The parts on the left are early FJ1100. The parts on the right are late 1100 & FJ1200.

That looks like a curve bottom slide needle on the flat bottom slide as well. You will need to slide the plastic piece off the needles and see if there is a number stamped at the top.

Either way, you are most likely going to have to update to the later parts to make them the same since the flat bottom slide are obsolete and harder to find than rocking horse dung.

Time to break them all down and see what you have. Take photos of the springs and measure the big hole in the bottom of the slide to see if they have been drilled out too.

Robert what is the Point of drilling the hole in the slide? Thanks

[fj1289]

The parts on the left are early FJ1100. The parts on the right are late 1100 & FJ1200.

That looks like a curve bottom slide needle on the flat bottom slide as well. You will need to slide the plastic piece off the needles and see if there is a number stamped at the top.

Either way, you are most likely going to have to update to the later parts to make them the same since the flat bottom slide are obsolete and harder to find than rocking horse dung.

Time to break them all down and see what you have. Take photos of the springs and measure the big hole in the bottom of the slide to see if they have been drilled out too.

Robert what is the Point of drilling the hole in the slide? Thanks

Some jet kits will have you drill out the hole to change the rate at which the slides react to the vacuum signal above the diaphragm.  Similar to the different slide springs some jet kits will come with. 

[FJ_Hooligan]

Also consider getting some new #40 pilot jets, 117.5 mains and (4) shims for your needles, .....

I think Senile Padre meant to recommend the #42.5 pilot/idle jet size.  

Also, unless you have a performance exhaust or other engine mods, I wouldn't go bigger than #115 main jet

And I would second the recommendation on the RPM carb bolt kit.  Whoever thought that up was a Freakin Genius

[fj1289]

Also consider getting some new #40 pilot jets, 117.5 mains and (4) shims for your needles, .....

I think Senile Padre meant to recommend the #42.5 pilot/idle jet size.  

Also, unless you have a performance exhaust or other engine mods, I wouldn't go bigger than #115 main jet

And I would second the recommendation on the RPM carb bolt kit.  Whoever thought that up was a Freakin Genius

Yes he was!  Thanks 

[stou]

Also consider getting some new #40 pilot jets, 117.5 mains and (4) shims for your needles, .....

I think Senile Padre meant to recommend the #42.5 pilot/idle jet size.  

Also, unless you have a performance exhaust or other engine mods, I wouldn't go bigger than #115 main jet

And I would second the recommendation on the RPM carb bolt kit.  Whoever thought that up was a Freakin Genius

Ok, so with Uni pod filters with stock exhaust and engine, it is #42.5 pilot jet, not #40 and #115 main, not #117.5.  Thanks!

[stou]

On another thread http://www.fjowners.com/index.php?topic=18936.msg192062#msg192062, I found the "Carburetor jet size calculator" https://raggedmoto.com/carburetor-jet-size-calculator/

With stock #110 main and #40 pilot, it give me #112.5 main and #41 pilot with pod filters and stock exhaust. On RPM website, there's only #40 and #42.5 pilot jets available. I think I will order the #112.5 and #42.5 but I will start to run the bike with #112.5 and #40 first and see what it look. If it's too lean I'll install the #42.5.

The calculator give #115 and #42 for pod filters and aftermarket silencers

[Pat Conlon]

...And I would second the recommendation on the RPM carb bolt kit.  Whoever thought that up was a Freakin Genius

I bow to the original FJ Forum Carb Guru.....

David Raforth has forgotten more about FJ carbs than I currently know....(check out the Carb Files)

(Although #40 pilots worked fine for me)

Stou, our CV carbs are very tolerant (by design) to air density changes (affecting air velocity) from temperature, humidity and/or elevation differences....as compared to non CV style carbs. That's why CV carbs are a better choice for street bikes which see these different conditions.
The link you provided, the Ragged Moto carb jet calculation is fine for non CV style carbs (e.g. flat slides) where elevation and temperature is a concern, and each race track requires different jets depending on time of year.... but, again our CV carbs are more tolerant.  The Ragged Moto calc confirmed #40 and 117.5 mains for me using the default settings (sea level, 70*F)

My point....get your jetting close and the vacuum from air velocity thru your CV carbs will raise or lower the slide and needle where it should be... with normal street riding your needle height is 80% of your tuning.