After market carb help

[Physician]

I was looking for good carba that will be smaller on top than oem bs36 for my 1127 popup katana and came across these today. They are on a 86 750.. looks like mikuni RS? what are they exactly? Im not used to aftermarket carbs..

And will they do the job on my 1127? 750 usualle came with bigger carbs than 1127.. 

So good or bad? 500$ can for running carb with the engine.. 

Edited June 9, 2022 by Physician

[Nik]

1985-87 GSX-R 750 ran Mikuni VM29 carbs (except a few countries, incl. the U.S.). They were designed as 33 mm, which was considered too big for the 750, so Mikuni made new castings for the body housing part facing the filters. Therfore, the filter side is 29 mm, while the head side is 33 mm.

You could run your 1127 with them, as is, but you would lose quite a lot of top end power. However,  it is easy to remove the 29 mm housing part, and any decent machine shop could enlarge it in a mill to 33 mm easily. Then you'll have some very nice carbs for the 1127. Not as much top end power as if you have RS36/38, but very smooth and nice.

I had 33s on an earlier bike (7/11 with 1127 F), and it ran wonderfully. 

Edited June 9, 2022 by Nik

[Physician]

Thanks for the informations, i did not know these were stock.

I will have to take a look.

[Upshotknothole]

Those look like Mikuni RS carbs, probably 36 but ask. If they’re 34s, I’d pass on them, 36s work on an 1100, not as much top end as 38s, but more useable power for the street. 

[cnap504]

If you got the engine and carbs for 500 I’d say you did very well.  The U.S. 1052cc GSXR (‘86-‘88) came with 34mm cv flatslides, I think modifying your 29’s to 33’s could work, the 1052 and early 1127 heads are probably the same.  And it would be pretty cool to make use of the carbs you already have.  The 33’s will lack just a bit of higher rpm power but do you need the few extra ponies a couple thousand r’s just under the limiter.

Edited June 11, 2022 by cnap504
correction

[Captain Chaos]

7 hours ago, cnap504 said:

The U.S. 1052cc GSXR (‘86-‘88) came with 34mm cv flatslides

34mm CV's.

[Gixer1460]

3 hours ago, Captain Chaos said:

34mm CV's.

Which technically do have a flat slide . . . . .  so you are both right LOL!