GSXR carbs

[RJ]

If you look on the "old Q&A" section under "performance" the first one or two entries is a piece about what great carbs the slingshots are when bolted up to the 1100. That got me going on these things but there's no specific info on jetting. I finally purchased a set. While looking for others with the same setup, I've come to find that guys are either running the BS34's, smoothbores, or RS's. Carter seems to be the only one who is actually running slingshots, and believe me I have dug all through this website for info. I guess it's going to be somewhat of a trial and error exercise.

[Anonymous]

Always is, I don't mind the experimentation, as long as I can make some progress.
I am looking forward to working with a set of reasonably pristine 8 yr old carbs (thanks again to Scotty) rather than a 23 yr old set that have been brutalized hacksaw modified. seems that shagged i( is this the correct syntax for this expletive?, maybe one of our GS kin across the pond will proof read for me, just ignore the typing, "Dammit Jim, I'm a Doctor (well ..in two more months), not a typist" ) idle mixture seats and threads were a big part of my idle problems.
Nyquil is making me punchy, time for sleep

Keep experimenting,
Derrick

[scotty]

i have the original katana air bo if you wnt to swap-I dont know if it will solve ur problm though. I hadn't gotten that far into the project

[RJ]

Well, you know if hot rodders from the 1950's could find a way to mate a flat head Ford to an Oldsmobile transmission, I think I can find a way to jet my carbs. I just would like to have a starting point close to where I need to be and not go through a million combinations of jets before I get there. Otherwise, long live the dinosaur GS and everyone have a good weekend.

[Anonymous]

After futzing around with my Semi-flatslide install I have a few observations to share.
1. After trying to cut my own boots, I jury rigged my torn boot with tape, andI have found that the stock 1100E intake boots can be used, it does take a little time to find the correct rotation to get the angle just where you want it. So I have ordered a new set of boots.

2. On the 96 Kat 750 carbs I am using, you can use your 1100E throttle cable, but it has longer action the the Kat, so you are near the end of the adjustment, also the cables exit angle is different, so you will have to reroute the cable to avoid binding. This is very important, because the return action on the Kat is much lighter than the 1100E, and will hang easily. I really like the carb mounted choke/enricher knob, it gets rid of some of the cable clutter on the bars and it has positive detents to keep it on when you want it on.

3. If you are going to try to match the downdraft angle, like I have (as opposed to adjusting the floats to compensate for the lack of angle) test fit your tank before you finalize any bracketry, the top of the far left carb will hit the fuel petcock with very little angle.

4. If you need to replace the fuel lines, you need thin walled line (Anybody know where I can find some?) because the OD of the correct ID fuel line from the auto parts store is too big, it will not fit between the carb bodies and if you route is outside, it is in the way for everything you do on the backside of the carbs.

5. there is a vacume port on the front right corner of the rightmost carb, that was not in my manual diagram, I used it for my fuel petcock vacuum. But it about drove me nuts looking for a vacuum leak. you can see it in the pic below


So after plugging my vacuum "leak" it starts, and even idles so-so. I still need to balance the carbs, and figure out the jetting.
I am thinking of eventually getting a dynojet kit for these carbs, maybe for the Kat 750, but I will see how it goes.

I will keep you informed

Derrick

[Anonymous]

On further review of the Dynojet website, it looks like the only difference between the kits for the GSXR1100, GSXR750 and the Kat 750, are the sizes of the mains, then needles and other stuff are all the same part numbers. I wil probably go with the late 80's GSXR1100 kit, and the biger jets.

Derrick

[HiSPL]

Try the clear fuel line that they sell for lawn mowers. That's what I'm using right now and it works well, with the added benefit of being able to see if the fuel is flowing or not...

[pano]

I bought a dynajet kit at:

http://www.overstockpartsgalore.com/jetkitmain.html

it seemed to be the best price I could find

[Anonymous]

Hey Pano,
on your GSXR 1100 what size pilots were in them? In the 96 Kat 750 carbs I have installed the stock were 32.5, I went to the 40's from my stock 83 carbs, but I think it is running too rich. It idles ok until it starts to warm up , then the Idle starts to dropp and finally stall.
Also, have you looked at the needles in your dynojet kit? how do they compare to the stock ones? I am also getting some blue balck smoke when I blip the throttle, maybe i shimmed the needles too high?

I guess if it were too easy, it would not be any fun.....but I am tires of having so much fun at idle

Derrick

[scotty]

my plan was to leave the needles stock position and just increase the mains to about 15((for my engine) I would say 107 for yours or something close. 130s if you have some flow mods like a exhaust or pods

[pano]

I haven't opened them up but the spec sheet says

main jet 122.5
pilot jet #40

The dynojet gsxr needles are sort of fat with a tapered tip. I havent looked at the stockers yet.

I just finished up installing slotted cam gears and dialing them in. I have to close that up and make sure everything is running right with my old carbs before I play with the GSXR carbs.

Man, its gonna be spring before you know it and I got so much to do!

[Anonymous]

Thanks guys,
I think you are right Scotty, I may have been a little too aggressive with my initial needle shim, especially since my stock needles have a second taper at the bottom.

Pano, thanks for the look, I think you are going to find that the dynojet needles are radically different than the stockers, at least if they are close to mine. My stock needles are slender and taper down to a more slender size about 3/8 inch from the bottom.
I did some additional digging on the schematics on bikibandit and found that the GSXR1100 carbs changed in 1989. It looks like different slides, and such, The part numbers list for the 86-88 pilot jets do not give a size, but after 89 they are pretty uniformly #30. And the mains as 122.5.
But the stock jets that I pulled out of my Kat carbs are 32.5's.
I guess that I will start by dropping my needles a bit and see how it runs (at least I don't have to pull the carbs to get the needles) and if it is still rich down low, I will put the 32.5 pilots back in.

till next time,
Derrick

[Flo]

Gixer-carbs on GS

Hi,
I am new registered in this forum, but sporadically reading it during the last years. Really nice institution, I miss something comparable in Europe...
However to the facts, not boring someone :-)
I got a GS1100. Has Laser 4-1 street legal, K+N dual-filters, 36mm-R-carbs with orig. needles and stuff (whatever it had, I dont even know from which type of Gixer they come) except the main JEts: 142,5.
runs quite fine on the road! No deep holes

maybe a point for someone else to start.

I was a bit surprised, that according to my O2-meter even the idle and lowend mixture is nearly perfect... real o2-testing was not possible, because since I got the o2-meter installed there always was snow or ice or salt on the road... and its no fun to do the fullthrottle testing under these circumstands :-)
Minor changings were necessary to the cable and choke assembly (I got my choke lever from a -E at the handle bar allthough I got an old KATANA).
at least the Gixer-carburators with 36mm diameter (used 88-92 indifferent models, maybe also on the GSX-F, I think in the US its also called "Katana") will fit to the old GS-engine witthout bigger problems. I cant tell exactly for the bigger ones. and the older ones (85-88) I would not use...

Greets
Flo

[scotty]

welcome Flo--i was hoping that dereck would leave the carbs stock except for the main het for the initial test and then go from there if the plugs read poorly

[Anonymous]

Hey, I'm learning as I go .
I have gone back to the stock 32.5 pilots, mikuni 130 mains and 1.3mm shim in the needle. The method to my madness was that I would rather start out a little rich and work my way back rather than starting out lean.

Either way, I picked up the new intake boots tonight and will hopefully get back to leak free tuning tomorrow.

FLO: So it seems to run well in the midrange, on the stock needle? Are those mikuni 142 mains or dynojet?
I appreciate the starting point and help from all involved. I will post an update tomorow.

Derrick