Author Topic: Mikuni RS34's & CB 750  (Read 38654 times)

0 Members and 1 Guest are viewing this topic.

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Mikuni RS34's & CB 750
« on: March 14, 2011, 02:25:49 am »
CycleX sells Mikuni RS34's spaced to fit the 750.I assume they can be used with late model carb boots.

Has anyone tried these? I know they are very nice carbs and easy to deal with, both my GS's work great with RS40's and tuning them is made extremely easy.

Would be a lot cheaper option than the TMR32's I've been dreaming about  ::)

Before anyone says they are WAY TOO BIG for a stock engine, my engine isn't exactly stock  ;)

 Juha

Offline Retro Rocket

  • Eggs are hard due too a
  • Really Old Timer ...
  • *******
  • Posts: 19,279
  • ROCK & ROLL
Re: Mikuni RS34's & CB 750
« Reply #1 on: March 14, 2011, 02:35:36 am »
Subscribed. Very interested to hear the reply's Juha I wish to use some on a second engine i have {no where near stock} and i am curious, if you buy someand If you have any Suzuki rubber velocity stacks can you post here if the stock GS stacks {34mm} fit the Mikuni 34mm carbs. I wish to use some sort of airbox or Tintops "antipod" and both need rubber stacks....

Mick
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Re: Mikuni RS34's & CB 750
« Reply #2 on: March 14, 2011, 03:21:24 am »
I'll take a look and let you know Mick.
However, I did use the same K&N filters in both, stock GS 34mm Mikuni's and the RS40's and they fit fine.

 Juha

Offline Retro Rocket

  • Eggs are hard due too a
  • Really Old Timer ...
  • *******
  • Posts: 19,279
  • ROCK & ROLL
Re: Mikuni RS34's & CB 750
« Reply #3 on: March 14, 2011, 03:58:51 am »
Ah, ok. If the K&N's work then i see no reason why the stock rubber stacks won't then......

Thanks mate...
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Re: Mikuni RS34's & CB 750
« Reply #4 on: March 14, 2011, 04:01:39 am »
Ah, ok. If the K&N's work then i see no reason why the stock rubber stacks won't then......

Thanks mate...
That's what I thought too, no worries mate  ;)

Offline mick7504

  • Old Timer
  • ******
  • Posts: 3,740
Re: Mikuni RS34's & CB 750
« Reply #5 on: March 14, 2011, 04:09:52 am »
Hi Juha

I have a set of these 34mm Mikunis on their way now with K&N's for the Billet Block Engine.

The TMR32's are still in my dreams at the moment, and while they'll be in my dreams for a while longer, these RS34's are very realistically priced.

I don't know what the setup is for adapting with the late model carb boots but I would assume that it's doable.
Mike or Ken would know.

Mick
If I was you
I'd be worried about me.

Offline Doctor_D

  • Hot Shot
  • ***
  • Posts: 722
Re: Mikuni RS34's & CB 750
« Reply #6 on: March 14, 2011, 07:40:16 am »
Not like I'm in the market for new carbs, but I'm as interested as anyone in a report on the RS34's and/or TM32's.

My CR's work well enough on the dyno, but an accelerator pump and a few more cfm's can't hurt.  ;)
Take care,
David
___________________________________________
1975 CB 750F - Project page: http://forums.sohc4.net/index.php?topic=66026.msg725479#msg725479
1978 CX500
1971 Norton Commando

Offline dragracer

  • Really Old Timer ...
  • *******
  • Posts: 5,027
  • CB750F Dragbike
Re: Mikuni RS34's & CB 750
« Reply #7 on: March 14, 2011, 06:27:27 pm »
I've got a set of 36 Flatsides on my F" model and i love the performance. I drag race the bike only- no street riding though. 1030cc with an RC 327 cam on a ported F model head with stock valves.

http://www.newdayphoto.phanfare.com/5044525    Note the dial in. I ran quicker on the first run out of the trailer but dialed it up for first round of eliminations. The bike has run a best of 6.55 in the 1/8th mile when i was about 10lbs lighter and raced it weekly.

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Re: Mikuni RS34's & CB 750
« Reply #8 on: March 16, 2011, 03:56:22 am »
Hi Juha

I have a set of these 34mm Mikunis on their way now with K&N's for the Billet Block Engine.

The TMR32's are still in my dreams at the moment, and while they'll be in my dreams for a while longer, these RS34's are very realistically priced.

I don't know what the setup is for adapting with the late model carb boots but I would assume that it's doable.
Mike or Ken would know.

Mick
Hi Mick.
 I agree on the pricing, TMR's cost more than most cars I've ever had  ::)
Please post some pics when the carbs arrive.

 Juha

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Re: Mikuni RS34's & CB 750
« Reply #9 on: March 16, 2011, 04:05:18 am »
I've got a set of 36 Flatsides on my F" model and i love the performance. I drag race the bike only- no street riding though. 1030cc with an RC 327 cam on a ported F model head with stock valves.

http://www.newdayphoto.phanfare.com/5044525    Note the dial in. I ran quicker on the first run out of the trailer but dialed it up for first round of eliminations. The bike has run a best of 6.55 in the 1/8th mile when i was about 10lbs lighter and raced it weekly.
That's one quick SOHC you got there. What did you use for carb boots?

Offline Retro Rocket

  • Eggs are hard due too a
  • Really Old Timer ...
  • *******
  • Posts: 19,279
  • ROCK & ROLL
Re: Mikuni RS34's & CB 750
« Reply #10 on: March 16, 2011, 04:08:52 am »
Hi Juha, how about some pics of that Suzuki ... ;D
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Re: Mikuni RS34's & CB 750
« Reply #11 on: March 16, 2011, 04:13:41 am »
Hi Juha, how about some pics of that Suzuki ... ;D
I don't mind posting them but there's a lot of people here who seem to like Honda's quite a lot  ;)
Ok, one picture  ;D

If you like some more pics, I can send some by PM.
« Last Edit: March 16, 2011, 04:19:14 am by Leino »

Offline turboguzzi

  • Old Timer
  • ******
  • Posts: 4,072
Re: Mikuni RS34's & CB 750
« Reply #12 on: March 16, 2011, 04:41:41 am »
hei Juha

dont know how vintage drag racing is run, but in road racing, carbs have to follow the bike's period = no flat slides till 83'.... dont you have similar limitations in your class?



TG

Offline mick7504

  • Old Timer
  • ******
  • Posts: 3,740
Re: Mikuni RS34's & CB 750
« Reply #13 on: March 16, 2011, 04:45:22 am »
Hi Juha

I have a set of these 34mm Mikunis on their way now with K&N's for the Billet Block Engine.

The TMR32's are still in my dreams at the moment, and while they'll be in my dreams for a while longer, these RS34's are very realistically priced.

I don't know what the setup is for adapting with the late model carb boots but I would assume that it's doable.
Mike or Ken would know.

Mick
Hi Mick.
 I agree on the pricing, TMR's cost more than most cars I've ever had  ::)
Please post some pics when the carbs arrive.

 Juha
No problem Juha
They should arrive within the next week or so and I'll get some photos up on here.
Mick
If I was you
I'd be worried about me.

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Re: Mikuni RS34's & CB 750
« Reply #14 on: March 16, 2011, 04:46:35 am »
hei Juha

dont know how vintage drag racing is run, but in road racing, carbs have to follow the bike's period = no flat slides till 83'.... dont you have similar limitations in your class?



TG
Hi TG.
No limitations to carbs in Streetbike-class.
I wish there was vintage drag racing in Finland but no, I race against all the hi-tech guys  ;)

 Juha

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,058
Re: Mikuni RS34's & CB 750
« Reply #15 on: March 16, 2011, 08:40:50 am »
Using the standard rule of thumb that 6.55 1/8 mile bike.. runs around 9.90 in the 1/4.. is that correct.. or at least Very low 10s../
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Leino

  • Not much of an
  • Expert
  • ****
  • Posts: 1,178
  • in drag racing since 2005
Re: Mikuni RS34's & CB 750
« Reply #16 on: March 16, 2011, 12:22:44 pm »
My personal best so far has been 6.479 / 9.932 so your calculation must be close 754.

Juha

Offline dragracer

  • Really Old Timer ...
  • *******
  • Posts: 5,027
  • CB750F Dragbike
Re: Mikuni RS34's & CB 750
« Reply #17 on: March 16, 2011, 08:39:39 pm »
Using the standard rule of thumb that 6.55 1/8 mile bike.. runs around 9.90 in the 1/4.. is that correct.. or at least Very low 10s../

The best 1/4 mile time on the bike was a 10.58. The bike is geared primarily for 1/8th mile racing so its flat out by the time i reach the 1000 foot mark. Backhalf numbers are really terrible.

I think a 6.25 1/8th mile time equates to a 9.90 in the 1/4 mile.

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,058
Re: Mikuni RS34's & CB 750
« Reply #18 on: March 16, 2011, 09:37:17 pm »
 I know some bikes, really low geared ones can be way better in  1/8th than 1/4 mile.
 But wayy way back when, I had a formula, maybe it worked better on 10 second & plus stuff..
 Add half to the ET, and a 1/3 to MPH to get difference from 1/8 to 14 times..
 maybe its more like 1.6 than 1.5.. but more often than not, it was eerily close... ;D
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline dragracer

  • Really Old Timer ...
  • *******
  • Posts: 5,027
  • CB750F Dragbike
Re: Mikuni RS34's & CB 750
« Reply #19 on: March 17, 2011, 07:32:34 pm »
I've got a set of 36 Flatsides on my F" model and i love the performance. I drag race the bike only- no street riding though. 1030cc with an RC 327 cam on a ported F model head with stock valves.

http://www.newdayphoto.phanfare.com/5044525    Note the dial in. I ran quicker on the first run out of the trailer but dialed it up for first round of eliminations. The bike has run a best of 6.55 in the 1/8th mile when i was about 10lbs lighter and raced it weekly.
That's one quick SOHC you got there. What did you use for carb boots?


I had F model boots from a 78 i think. The carbs i selected had very close spacing to the Honda's. They fit both FJ1100 Yammies and 85 Ninja 900's- Mikuni 36mm flatslides that i bought new. I had a stock set of CV's from the 900 that i wanted to use but they were so gummed up i quit with them and went with the new Mikunis. Because the spacing was so close yet the carb boots were a bit to small, i offset ground the boots (stone on a die grinder)to match the spacing of the carbs. I took a little more material off of whatever side of the boot i needed top match the rack of the carbs. It didn't take long as they were really close to begin with. The bike is very responsive with those carbs eventhough they are to big for the motor. I venture to say a set of 34's might have been best for my 1030cc motor.

Offline voxonda

  • Master
  • *****
  • Posts: 2,231
Re: Mikuni RS34's & CB 750
« Reply #20 on: March 26, 2011, 08:41:30 am »
Got a set of 34's too, and want them on my F2 engine. Heard about using the rubber boots of a KZ(DOHC), anyone familiair with that? I know they are big, but like to try them. Hoping to open the engine to 850/900 soon, with a .370 cam. Currently 41a.

Rob.

edit: My mistake no RS34's but VM33's
« Last Edit: March 27, 2011, 01:53:05 pm by voxonda »
Better sorry for failing then for the lack of trying.

Offline MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,471
  • Big ideas....
Re: Mikuni RS34's & CB 750
« Reply #21 on: March 26, 2011, 09:34:41 am »
Got a set of 34's too, and want them on my F2 engine. Heard about using the rubber boots of a KZ(DOHC), anyone familiair with that? I know they are big, but like to try them. Hoping to open the engine to 850/900 soon, with a .370 cam. Currently 41a.

Rob.
The Z/KZ boots have a flange that bolts on to the head Rob
Owner of the "Million Dollar CB"

Offline voxonda

  • Master
  • *****
  • Posts: 2,231
Re: Mikuni RS34's & CB 750
« Reply #22 on: March 26, 2011, 09:55:03 am »
Hey Mike,

Yes, the Kawi's have but not the Honda KZ 750 (DOHC) ;)

Cheers, Rob
Better sorry for failing then for the lack of trying.

Offline mick7504

  • Old Timer
  • ******
  • Posts: 3,740
Re: Mikuni RS34's & CB 750
« Reply #23 on: April 04, 2011, 09:03:00 pm »
Here are some photos of the Mikunis that arrived yesterday.
I wasn't sure what I was going to use for the rubber manifolds on these as the spigots are 40mm.
I had a new set of Honda K rubbers which were tight to get on, but they have snapped on perfectly with a small amount of lube and some even downwards pressure.
Mick







« Last Edit: April 04, 2011, 09:09:09 pm by mick7504 »
If I was you
I'd be worried about me.

Offline Retro Rocket

  • Eggs are hard due too a
  • Really Old Timer ...
  • *******
  • Posts: 19,279
  • ROCK & ROLL
Re: Mikuni RS34's & CB 750
« Reply #24 on: April 04, 2011, 10:03:38 pm »
Gday Mick, are there velocity stacks that suit the RS carbs .?
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.