gsxr slingshots on gs1100 float height?, HELP!

[gsBert]

hi,

i need to know what your float height is measured from the gasket surface to the bottom of the float, with the carbs upside down and the float just touching the tip of the valve.

note that i need this info for a set or bs36ss carbs (the gsxr slingshots, semi-flatslide cv carbs) mounted on a gs 1150 or gs1100 engine.

the engine configuration does not allow the carbs to be tilted forward as on the gsxr, so i assume the stock gsxr float height will be wrong.

if you've been experimenting and have gotten these carbs to work on any of these 2 engines with a pipe, pods or even in stock form, let me know what your setup is please, im going crazy.

while youre at it, gimme all your jet sizes (pilot, main, needlejet), number of turns for the mix screws, and needle number (model) and clip position.

also, one of the 2 air holes at the bottom of each slide was epoxied over on my carbs, i'm told this is to compensate for the different engine stroke from the gsxr and the 1150, and was easier than messing with diaphragm spring rates. im really tempted to unclog those holes, should i?

 

[RacingJake]

I got the 38mm cv's and used a hose clamp on the frame under the tank to pull the carbs up as high as they could go until the petcock hits the top of the carb. I just kept lowering the floats until they stopped leaking out the back of the carbs. I don't used any filters just some cut down 7oz kids sipper cups as stacks and when I wack the throttle the slides go full open. My slide holes are not plugged, stock needles and pilot's just bigger mains. Since it's a dragbike I'm running 160's mains. I have'nt even touch any of the mixture screws. I also use one of those motorcycle filters about the size of a half dollar to keep all the crap out of the carbs.

 

[lecroy]

I don't used any filters just some cut down 7oz kids sipper cups as stacks

I would expect nothing less!!!!

 

[stiksave]

Bert,

Maybe this will help. http://www.mikuni.com/pdf/rs_app_parts_lists.pdf Let me know how you make out. I've got a set coming in from e-bay that I want to try.

Chris

 

[gsBert]

i got a set of rs36 flatslides on the other 1150 (the red one that's for sale). nice carbs, but i want to get my slingshots to work...

the slingshots will give smoother delivery and compensate for user errors.

the mechanical slide carbs (RS) are very sensitive to throttle and you have to be smooth when opening the throttle up (get a feel for revs and engine loads), if you just whack it open at teh wrong rpm/load, youll just drown your engine with way too much fuel.

do not ever forget that these carbs have an acceleration pump, so never ever twist the throttle when the engine is off ok???!!!
some !@##!@ kid did this to my bike while it was parked, i almost drained my battery trying to start the engine... (super flooded i tell ya)

i really like cv carbs, they compensate for altitude/temperature/engine load, and if you want to go fast, just whack it open and let the diaphragms do their thing...

the RS are easier to jet and tune as your brain provides the computing for throttle position, but while they do give more power in the right hands, i find they act too much like an on/off switch for street use (i'll never ever drive the red 1150 in the rain again, the blasted thing goes sideways when you try to pass someone) and they are tiring on the right hand for long tours...

also, i find power delivery to be a bit unpredictable with them (might be the other engine mods in combination), i never know what will happen when i open up the throttle, it's very interesting, sometimes it'll wheelie, sometimes it'll spin the rear tire, and sometimes it'll just bog down...
all from the same speed at the same load same temperature and same rpm on the same road... 4th and 5th gear are ok though unless youre going over 100mph then the power gets twitchy again...

if you're a power-junkie, you'll love the rs carbs though, hope you got a good deal on them... and you do get used to them, going back to a cv carb feels safe and slightly slushy...

back to my slingshots:
i finally got the bike to run!!!
i replaced the pipe with the 4:1 off my 750 (took some hammering but it fit, the supertrapp header will require some machining but is going on this winter)
i also drilled those slide holes (the ones that were epoxied shut) after flow benching the carbs using my vacuum cleaner.

the bike used to run super rich (too much backpressure combined with the slides raising too fast and staying up too long). the slides now follow the butterflies nicely.

im now running too lean on the needle jet but the needle is adjusted at the lowest position ill raise it 2 notches tomorrow (by lowering the e-clip).
i havent been able to do a plug chop at full throttle, i ran out of balls and road, but ill go on a dyno for that....

if im still runnign too lean, ill lower the float height (measured with the carb upside down) when i have the needle all the way up, but i should not need to, im in the ballpark...

 

[stiksave]

Bert,


I Paid $31.00 plus shipping. They are 36mm RS carbs. I was going to try them on MY 1100, 4 X 1, pods. Any info on your settings in general, or just try them how they sit? To me the cv carbs seem too high maintenance, just my opinion. Probably because I'm still learning. Anyway, I just got a new set of intake boots from my dealer, he loves me $39.50 with tax. Old guy discount I guess. I didn't want to play with the carbs without new boots. If these set level like the cv's, I can use the settings from Mikuni pdf, probably for the gsx-r1100.

Thanks,
Chris

 

[gsBert]

31$????

it's my understanding that these carbs sell for 1000$ and sometimes more....

build some sort of bracket to hold them in place. or you can ziptie from the frame...

they tilt downward, dont leave the petcock on prime, lol youll flood your engine

 

[stiksave]

http://www.thegsresources.com/_forum/viewtopic.php?t=41750&highlight=

 

[Billy Ricks]

Those are stock CV type carbs. They are probably flatslide CVs, but they aren't RS flatslides. Float height is generally around 21mm for most Mikuni CV type carbs.

 

[gsBert]

sorry dude, those are NOT rs-36 carbs...

the diaphragm cover should have given them away immediately...

the 31$ price couldve also given it away. i saw a set for sale for 1500$ us once...

 

[RacingJake]

34 to 40RS are between 559 to 599 new.

 

[moto_dan]

Some additional info
http://www.mikunioz.com/rs_kits.htm

 

[Billy Ricks]

Some of the Yoshimura modified RS carbs could have run $1500 or more. They used special slides and some of the really serious carbs had the slides riding on needle bearings. I know on the AMA Supersport bikes of the early '90s Yosh was running hollow jet needles with fuel nozzles up and down the needles. As the slides rose more nozzles were exposed. These were for CV carbs but they may have been using the needles in the racing flatslides as well.

 

[stiksave]

OK, so I made a testicle out of myself. The stock carbs on my 83 1100E have round slides. Are they also cv carbs. What threw me was the slides, they are exactly like the radial flatslides on the RS model. So, getting back to these, can they be set up for my 1100? Will I get any better performance? Put them back on E-Bay? Stop buying stuff?

Thanks,
Chris

 

[Billy Ricks]

They can be set up for your bike with a little work. If it doesn't already have a jet kit installed contact Dynojet by phone and tell them what you're doing. Chances are they can point you in the right direction and supply you with a kit that will work.

 

[stiksave]

Here's what I've been able to dig up on these carbs. They are Mikuni BDST 36MM. They are from a 1994 Suzuki RF900. The stock jets are 130's. I think they are down draft, so the have to be tipped like the flatslides. Here's a description of the bike, http://www.mcnews.com.au/Testing/rf900.htm . I do have a pair of 2 x 2 K&M's that would help with room for the tipping if the carbs. The next question would be, will they be an improvement over my CV roundslides with dyno stage 3 installed? The jets in my carbs are 135's. Next question. Is there a good exploded veiw and spec chart for this carb some where?

Thanks,
Chris

 

[gsBert]

not to be a pain in the backend here, but make your own thread...

do you guys realise that this thread "help me with my float heights with gsxr slingshots on an 1150 engine" has been completely hijacked...

we're discussing a different carb on a different engine, on a different bike.
thansk for all the help, really, should i feel slightly upset?
i mean its interesting readingf and all, but everytime i see a reply to this post i get all excited becasue someone might have posted their actual float heights, only to find out what i already knew: the rf 900 carbs suck on the 1100 engine.

what you want are either slingshots or rs36, but if you plan on doing any street driving you want the slingshots, all you need is to get your hands on some (flatslide cv carbs) and pray (as i do) that someone posts the correct float height for our engines...

 

[stiksave]

Sorry Dude

 

[pano]

gsBert,

I dug this all up from searching this site a while back. There is some reference to the float heights in here. I have a set but have not had the time to fiddle with them yet.


........After having read many posts about the GSXR Slingshot carb mod for GSs, I obtained what I am pretty sure are some '92 Slingshot carbs for my '81 GS1100E. However, upon inspection, they appear to be downdraft carbs, with the bowls at about a 15 degree angle. Does anyone know if this will be problematic in terms of spilling fule into the cylinders, and does anyone have a solution? I would really appreciate some advice, before I wash out my cylinders and blow my engine. Thanks for any help.

Austin

I'm running the 90 GSXR 11's (36mm) on an 1150 with no problems now. I too was concerned about the angle. I had to lean the float height considerably to get it to run right. I bought my carbs used, and I think they may have been fiddled with previously.

The dyno jet kit that came with the carbs had these super blunt looking needles and huge mains. I fouled about 24 plugs, four at a time, until I leaned the floats.

In the meantime, I bought a Factory jet kit and the needles looked totally different, slim and pointy. I tryed these and fouled half the plugs mentioned above. My emulsion tubes, where the needle slides into, may have been fiddled with also so I stuck with the Dynojet kit. I'm using 32 pilots and 147.5 mains with the needle 4 notches down. I had it a 3 for a long while, but was experiencing detonation in the lower rev range. This change solved that..

I would reccomend a jet kit and K&N filters. If the idle adjustment screw is on the bottom it might need to be shortened, but if on the side with the long cable, no worries. The throttle cable needs to be shortened or a GSXR used. I modified my stock throttle housing to accept the GSXR cable, as it has a different end. Carter

Carter,

Do you have your carbs tilted somehow (like tied up to the frame) to level out the float bowls, or did you just leave them straight, with the float bowls at an angle? What height did you set the floats at, and are you sure that there's no raw fuel seepage into the cylinders? Have you ever checked the intake boots after riding to make sure that there's no fuel seepage? Are your plugs the right color? I want to use these carbs, but I'm nervous about cylinder washout. Any other information from you or anyone else would be extremely useful. Thanks to all.

Austin

Austin

I dont have them tilted, but I did fabricate a crude aluminum bracket to support the carbs to the frame. I mounted on the top of the inner carbs to the bar that supports the four carbs and connected to the two holes in the frame where the airbox used to mount.

The reason for the brackets is to support the weight without an airbox, but also maybe half a dozen times, I've started the bike and the negative back pressure or whatever its called, blew my carbs right off the boots. I also had three boots burst on startup.

Hopefully this is caused by the backpressure and not seepage.

My plugs tips almost look like they do when new, but inside the threads are darker. I actually think I'm running a little rich, but thats to cure the detonation on the 1229 with a little more compression than stock.

The floats are set at 17-18mm, almost as far as you can go. I had a shop do it as my hand dexterity is clumbsy.

When I've taken my carbs off, I noticed residual fuel on the ends of the boots, but I recall this with stock carbs too.

The power delivery is amazing, the pickup off the bottom, and the lightness of the twistgrip is addicting. Feels like a new engine.

One hot tip is to mount the cable to the carbs before installation, then route the cable through the frame. Try it the other way and you'll cussing and cursing. Carter

If you can get a copy of a book titled "Superbike Preperation" by Jewel Hendricks, it goes into detail on this subject and many others dealing with engine and suspension modifications. It was written in the mid 80's and it deals with these older bikes before fuel injection and shim-under bucket valve trains became the norm. My copy is full of greasy thumbprints, it is well worth the $20 or so bucks. Ride On, Ed.

I'm running GSXR carbs on my 83 Kat. It does have an 1150 motor in it but I dont' see a problem running them on the 1100 as I've tryed 36mm 1150 carbs on my 80 1100 with no problems except a rich idle circuit or improper float height.

I'm currently using 90 36mm GSXR 1100 carbs with stage 3 jet kit and dual K&N's. I think you'll run into problems trying to plumb them on a stock 1100 airbox setup.

I had to fiddle a bit with float height as I was told the GSXR carbs are sensitive to float height. I was told to start at 14mm float height but ended up fouling numerous plugs over and over until I set them at 17-18mm. Actually you may have better luck with a Factory jet kit and 14mm may work. I bought a Factory jet kit and tryed to install them in the carbs that had previously housed a Dyno Jet kit and I think the copper emulsion tube that surrounds the needle had been bored out before I bought them. That maybe why I was fouling plugs.

The throttle response was impressive and more immediate with lighter throttle action. The main jets were Dyno Jets equivalent to roughly a 160 Mikuni which seemed a bit big. I'm now running 145's.

Its a bit surgy around 2500-3000 rpms in 2nd and 3rd around town stuff and a delicate throttle hand is required at this low steady rpm. Otherwise its a vast improvement throughout the rpm range. Felt like a new motor was installed the first time I dialed them in right.

I did have to shorten the throttle cable, running a GSXR cable housed in the stock 1100-1150 throttle assembly. I also had the idle speed adjustment screw shortened as it was touching the cam chain tensioner.

I'm running a Pingel petcock with no vaccum line. You also must use a T- fitting to plumb the dual fuel line from the carbs. It's a go if you're into a little fiddling. I don't know anything about accelerator pumps. Carter Turk

 

[Flo]

have two GS bikes running with such carbs (GSXR and BAndit). Never cared about that float bowl height thing. Just set them up like in the GSXR-handbook, runs fine!

I run:
-org. 83 GS1100E-Motor
-36mm CVs from some 1100 Gixer, dont know exact year, might be 90
-K+N-duplex
-Laser 4in1 full with street legal pot

needle, air corrector jets and stuff all org. (dont know numbers, whatever was inside)
idle screw 3 turns out
142,5 main jets
O2-meter shows great reading, full throttle at > 6500 rpm could be richer. Is close to lambda1, great for economy, engine and environment, not perfect for power. But bike runs great, faster than I can drive of course, so no need to change. Better than with stock 34CVs from stoneage.

my other setup:
GS1150
-bored to 1200, 11/1 compression
-36 CV from 97 BAndit 1200
-Speedpro-4-1 with open Race-pot
-K+N-duplex
-HD150
-needles in highest postition + washer M3 under each (I know carbs are precision parts and washers arent... but it simply works great and was the only thing I has available)
-idle screws according to o2-meter (dont know how many turns, sorry)
here someone could go a bit richer too. But it runs GREAT (wheels 1st and 2nd). Correction for all out power should be done with air correctors as mid range is just perfect (acc. to O2 and my "seat of pants")

the BAndit carbs seemed to be set up much leaner in the mid range (Smog regulations?), so they need much more tweeking... easiest point to start are definetely the Gixer-parts.

the 1100 runs like that for two years now and I am really happy with it. It is in every way equal or better than the orig. setup or the 36mm 1150 carbs I tried. The modern carbs arent as worn out as the antique stuf, parts are cheaper and readily availabale and be honest: they are simlpy a more modern and tricked out design!
Manual Flatslides are fine for some people... I dont like them! I managed to slide out of a corner with a spinning rear wheel with the setup above, it really kicks enough!

I sold my GSXR1100W to my brother, up to 180km/h the fresh built GS1150 kicks his ass ;-)

Regards
Flo