90 or 93 carbs from a 750 GSX-R fit on a 91 750 GSX?

[takirb]

Does anyone know if i'll run into problems with this? i have some carbs from a 750 GSXR, but i need to resell them if they won't bolt right in. i believe the carbs i have are BST38SS, and in my GSX i have BST36SS carbs. Will they fit or do i need to fab them somehow? Anyone got experience with this?

Also, i'm new to the bike world, and have 0 riding experience. on the fuel petcock, what position do i need to leave it at if i'm not riding it? NEWB question, sorry, gotta start somewhere

[md86]

Not gonna be much help with the carbs , but here're some theories and info I've read . Bigger carbs can sometimes make more top-end power , but often at the expense of low and midrange grunt . The boots on the Katana are made for the 36mm carbs that come with it , so slightly larger carbs may have to be "made" to fit . I personally wouldn't do it . I ride around in the middle of the tach most of the time , so I'd be hesitant to give up much power there . You can always bolt them up to see if they'll fit , but they more than likely will not run great without ALOT of tweaking .
I know about the petcock though (and the subject is actually a "sticky" on here somewhere , I belive) . Keep it pointing down . That's "on/off" . Forward is reserve , back is prime . Don't put it on prime unless the carbs have been drained or it's been sitting a while .

[takirb]

Thanks for the info! actually, with the carbs, i bought them used off ebay, and after they arrived, i looked at the auction again and realized it said GSX-R, not GSX. so i'm just trying to utilize my money instead of reselling them to get the right ones. new carbs are quite pricey, and the ones on there now pour gas. they've been rebuilt, but the gas still pours through them pretty heavily (flooded my carport with gasoline). i'm thinking it may be as simple as replacing the needles/floaters, but the mechanic that was working on it said i needed to replace the entire assembly instead, dunno why though...

[illinoiskat]

I have read that the stock katana carbs are crappy, so maybe upgrading them would not be so bad. The GSXR block and GSXF block are the same for the oil cooler years. I dont see why it would not work.

The petcock PRI is only for starting it bypasses the vacum circuit. If your bike fell over on PRI fuel would spill everywhere. The strait up and down position is standard run postion, which is where I leave it. I only needed to use PRI twice, both times really cold weather. Below freezing.

[OldandReallySlow]

The carbs off an oil cooled GSXR should work. They will be alittle too much for a stock bike but with a full system and maybe an ignition advancer you might get by. The 93 carbs are from the "water-pumpers" and have a different spacing as a set. Guess you could dis-assemble the set and use your Kat parts to narrow the set down.

[Court93kat]

takirb-

Where in SC are you? If you are close enough I could come over and offer some assistance. I have had the carbs apart on my '93 quite a few times. Post back or PM me if you would like some help.

[The CyberPoet]

I have read that the stock katana carbs are crappy, so maybe upgrading them would not be so bad. The GSXR block and GSXF block are the same for the oil cooler years. I dont see why it would not work.

While the basic block is identical for the oil-cooled GSXR and the 88 - 97 Kats, the actual bore and stroke values for the two engines are significantly different, and that affects the ramp-up speed and vacuum levels the carbs are expecting at any instant. At minimum, rejetting the carbs to compensate would be necessary (as well as adapting a solution to fit the larger openings both to the airbox and to the intake stacks). In conjunction with the differences in the airbox designs, and given that you say you have zero experience working on bikes, my advice is to sell the carbs again and find the right carbs (or rebuild your existing ones).

Sidenote: GSXF vs. GSXR -- never simply search for GSX when scouring ebay

Cheers
=-= The CyberPoet

[takirb]

they bolted right up!!

"Sidenote: GSXF vs. GSXR -- never simply search for GSX when scouring ebay "

so i've learned, that and i hate it when people spell GSX in caps and put the lil' "r" in lower case lol

the carbs bolted right up. there wasn't a problem fitting them in since they connected to the intakes via a rubber hose w/clamp (only a 2mm difference in size). the bike fired right up, idled fine, revved fine, but only made it to the top of my street before it cut off. they seem to be doing the same thing as the stock carbs, pouring gasoline everywhere. we removed the cap on the crankcase and there's gasoline mixed in my oil. we don't know if it's from the GSXR carbs or the old ones, but either way i have to change the oil now. is it possible that the GSXR carbs are throwing out too much gas 'cause they're for a GSXR? what else would cause gas to run into the crankcase that way? both the shop and prev owner said the only problem with the bike was the carbs...

the guy helping me with this is taking my old carbs home to disassemble them and see what might need to be replaced. he already removed one of the bowls and said there was dirt all in there, so he's hoping that's the problem. the bike was in the shop for carb problems when i bought it, and the stock carbs were rebuilt there right before i picked up the bike, but i guess the shop who rebuilt them didnt' touch the floaters. they said that the carbs were still pouring gas for some reason, and i just needed to replace the whole set. if he's already replaced the seals and all and just didn't touch the floaters, hopefully that'll be all i need. i'm aiming to sell the GSXR carbs on ebay again and use the $$ for new floaters. other than that, any other suggestions? hearing that vance and hines pipe roar tonight is starting to get to me

Court93Kat - i live in greenwood, about a 1.5hrs from columbia. i'm pressed for time with it being holiday season and all, but if we can't get this straightened out by spring, i may see if we can work something out. thanks for looking out!

[Court93kat]

Re: they bolted right up!!

If the GSX-R carbs are doing the same thing as the original carbs, I would look into the vacuum line controlling the petcock or the petcock itself. Is there a continuous flow of gas from the tank? It is possible for both sets of carbs to need the floats cleaned which would cause the bowls to overflow and cause a lot of fuel to be pushed into the cylinder. It shouldn't be throwing too much fuel in because they are GSX-R carbs. It would be because of the float shut off.

I have the next two weeks off because of the holidays, just let me know if you need any help.

[takirb]

the guy tonight did tell me that he had to clean out the fuel petcock, and i needed to keep an eye open for another one if i can find one. he mentioned something of it having the filter attached, and that should be replaced as well. he's going to take the carbs apart and inspect the floats for me. if they're heavy i'll have to get new ones, but hopefully they can just be cleaned....

[md86]

Maybe you could work out a trade with someone (special K perhaps ?) . Your 2 sets of not working carbs for a set that DOES .