91-92 BST40SS carb parts / rebuild kits [Archive] - Suzuki GSX-R Motorcycle Forums Gixxer.com

: 91-92 BST40SS carb parts / rebuild kits


freezehawk
02-18-2010, 07:11 PM
Hello fellow gixxers

First real post in the forum, i hope it isn't stupid... I've seen a few messages dealing with this topic, but didn't really get a definitive answer, so...

I recently joined the gixxer world, acquiring a 91 GSXR 1100 (picture). Great machine, but it's a little unstable in low RPM's. Also, when you twist the wrist a little, below 5000RPM's, it stalls for a while and then gets back to full power.

I believe there must be a few bad/dirty parts on the carb so i figured out i'd do a little cleaning/synching.

The problem is... it came with a set of Mikuni BST40SS carbs (Brazil got the european model), and i can't really get the OEM/Aftermarket spares from the US market since those are BST36SS' and the jets/needles are different.

So my only option, for jets and other stuff, is to acquire them from an European/Canadian dealer. Are there any known dealers i can order parts from?

For other simpler parts, doing a little search, i stumbled upon Keyster kits (K-584 i believe). Are these any good? Will they fit in the BST40SS'? Those are easier to order from an US shop.

Thanks in advance,
Luis

BRYCE88
02-18-2010, 07:41 PM
WOW that thing looks new:punk

mike91 1216
02-18-2010, 08:07 PM
I am in canada...what exactly do you want? i can price it from my dealer,and send it to you...post here or PM me....

mike

oldboy
02-18-2010, 08:49 PM
From the US you can go to http://www.carbparts.com/mikuni/street.htm they have the RS parts in stock. Most likely a good cleaning, a bench sync and setting the accel pump should fix most of you woes. Nice bike.

freezehawk
02-18-2010, 08:52 PM
Thanks Bryce, the bike is in good shape. The previous owner didn't ride it that often.

Mike, really appreciate the help... I'm thinking about 4 kits of the 40mm-specific parts, which are the following... Not sure if all those are shot, but it's good to have them handy anyway.


09491-25010 - Main Jet (125)
09494-00721 - Jet Needle (P-2)
09493-24007 - Jet Air (1.2mm)
13383-41C00 - Needle, Jet (6zd13-3)
09492-40014 - Jet Pilot (#40)
13279-47070 - Screw Air (2.0)
13370-07D00 - Valve assy needle (don't really need this if the Keyster kit is good quality and fits the BST40SS')


Do you have any recommendation of carb repair/gasket kits you use in your bike?

Regards,
Luis

Intguy
02-18-2010, 08:53 PM
Very nice, still has the warning stickers on it LOL.


cheers

freezehawk
02-18-2010, 09:02 PM
From the US you can go to http://www.carbparts.com/mikuni/street.htm they have the RS parts in stock. Most likely a good cleaning, a bench sync and setting the accel pump should fix most of you woes. Nice bike.

Thanks for the tip! I had visited that site before from a link in the forum, but didn't find the BST40-specific parts i needed, probably because i couldn't figure out the part numbers and codes... :-(

Out of curiosity, when people talk about RS carbs, are those the same as BST's?

I'm just new to the whole carb model business... :-)

jdmcb3si
02-18-2010, 09:13 PM
yes the bst/rs carbs are the same. The CV carbs are the different ones.

mike91 1216
02-18-2010, 09:36 PM
40 bst carbs are a oem factory cv carb they are totally different than a mikuni rs flatslide....

so any rs parts will not work...

gimme a day or2 and ill send you the pricing... 4 of each correct

gotgixers
02-18-2010, 10:02 PM
what he^^^^ said is correct. BST's are factory Mikuni CV's. While RS's are Mikuni flatslide carbs. And the parts do not interchange...

freezehawk
02-18-2010, 10:20 PM
40 bst carbs are a oem factory cv carb they are totally different than a mikuni rs flatslide....

so any rs parts will not work...

gimme a day or2 and ill send you the pricing... 4 of each correct

Hum, OK. So the BST's are more like "semi" flat (one flat side, the other side is round), whereas RS' would be "full" flat slides, is that right?

As for the pricing, no hurry. Whenever you have them, let me know... 4 of each indeed.

FruitLooPs
02-19-2010, 04:48 AM
Sort of,

BST's are a CV (constant velocity) type that have one slide vacuum controlled (front one) and the round butterflies directly controlled by your throttle. It's done to make a smooth ride, with the vacuum opening the slide in a linear smooth fashion. Downside is has more parts in the way of airflow size for size with a flatslide carb (flows a bit less).

Flatslides just have a single slide that's controlled by your throttle, so if you whip them open hard in the wrong gear they will probably just bog down - they require more finesse with the right hand, often have dual push pull cables with a heavier feel than CV's use more gas but are faster in skilled hands.


they work in pretty different ways to get the same job done.

oldboy
02-19-2010, 06:49 AM
The differentce in the RS carbs are the bodies and what needles are used, CPW has a list of the basic builds and the diagram of the carbs will get you the part numbers.

ghostrider.1127
02-19-2010, 11:21 AM
change only emulsion tube and needles
your bike change totally
replace the jets are most of the time ,just waste money
(emulsion tube for 1127 91-92 engine one of the really big problem)

gotgixers
02-19-2010, 12:34 PM
Sort of,

BST's are a CV (constant velocity) type that have one slide vacuum controlled (front one) and the round butterflies directly controlled by your throttle. It's done to make a smooth ride, with the vacuum opening the slide in a linear smooth fashion. Downside is has more parts in the way of airflow size for size with a flatslide carb (flows a bit less).

Flatslides just have a single slide that's controlled by your throttle, so if you whip them open hard in the wrong gear they will probably just bog down - they require more finesse with the right hand, often have dual push pull cables with a heavier feel than CV's use more gas but are faster in skilled hands.


they work in pretty different ways to get the same job done.

Very well said ....

MrHotrod
02-19-2010, 07:34 PM
Doesn't factory pro sell kits for these carbs?

gotgixers
02-19-2010, 11:06 PM
I believe they do....

freezehawk
03-09-2010, 10:13 PM
I believe they do....

Looking through the factory pro site, they do have a 40mm kit. Looks like they even have the emulsion tubes made according to the stock specs... Nice!

Mike, did you have a chance to get those prices?

Thanks,
Hawk

91 Gixxer
03-09-2010, 11:55 PM
Hey Freezehawk, I'm not mechanical at all so I can't help on your question... but did at least want to chime in and say nice freakin bike! That really looks awesome! :punk

Cheers. :cheers