Author Topic: Anyone with Keihin CR Roundslide carbs on their CB750?  (Read 40524 times)

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Offline lordmoonpie

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #25 on: September 16, 2008, 01:52:23 PM »
Now is there anything else you want to know while I am rambling?  ;D ;D ;D

Sam. ;)

Sam - I'm worried! When did you take up rambling!?

If 29s are no good why did the Honda kit use 31s? Can't imagine Big H got it wrong and neither has Big Chris!!  ;D
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Offline turboguzzi

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #26 on: September 16, 2008, 02:39:33 PM »
kidnapping the thread a bit....

Hei Terry, if you ever want to get rid of those Mikunis 29's, PM me first.

A few weeks ago I lost on *bay a set of CR 29's to another forum meber by a small margin and it still hurts.

They will be put to good service on my racer.

Cheers

TG

Offline Terry in Australia

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #27 on: September 16, 2008, 05:44:23 PM »
kidnapping the thread a bit....

Hei Terry, if you ever want to get rid of those Mikunis 29's, PM me first.

A few weeks ago I lost on *bay a set of CR 29's to another forum meber by a small margin and it still hurts.

They will be put to good service on my racer.

Cheers

TG

They're for sale mate, according to one of the members here they've apparently been "re-racked" to the same carb spacing as a CB750, (you don't need to spend 150 bucks for some special inlet rubbers) I've changed things since I posted the 29mm Mikuni carbs thread awhile ago, I initially made some adapters for them (see pics in thread) but they were a bit big so I looked around and found some Sudco adapters that allow them to be used with OEM F2 or K8 rubbers. If you're interested, PM me with an offer for the carbs, my home made adapters (with vacuum guage ports) plus the Sudco adapters and velocity stacks. I was gonna put them on EBay this weekend, but I'll let you have "first refusal". Cheers, Terry. ;D
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Offline Terry in Australia

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #28 on: September 16, 2008, 06:04:40 PM »

Geez it doesn't really seem to rev that hard Sammy, I'm surprised?  :-\

It revs to 8,500 Terry, the same revs that Honda designed it to rev at as a road motor.
We could have made it rev higher, we could have built a race motor with more power.
What we wanted was a motor that could retake some of his strip records that had been lost to Z1s and the triple two strokes.
We didn't want a motor that we would be stripping down every 5 minutes, we wanted a trouble free few years of racing and that's what we have had and It's retaken his lost records.
As you know Terry, the more power you build into a motor, the more money you have to spend on building reliability in to it, Carrillo's etc.
We got what we wanted and the bike has done as it was asked with no fuss, that's all that Chris wanted.
If you want a screamer producing 110 plus HP no problem, if you want a 400+ blown nitro drag motor no problem (speak to you later Jay :D :D :D :D) It's all about how fast you want to go and how long you want it to last. Now is there anything else you want to know while I am rambling?  ;D ;D ;D

Sam. ;)
[/quote]

Sorry Sammy, didn't mean to upset you mate, what I meant was that it doesn't seem to accellerate all that rapidly, I'm a big bloke too (although not as big as Chris) and my K1 with the home built 836CC engine that cost me under 2 grand to build, rockets away from the line, even with me on it.

I wasn't sure if the clip was of Chris riding the bike with the original stock engine without Mikes head etc, I remember you were racing the stocker for awhile, but of course a film clip doesn't always do justice to what's really happening either, it's a "you had to be there" kinda deal, I know.

I've gotta play with the needle positions on my 29mm CR's again the K1 seems to be running lean from around 7K to 10K RPM, but from 0-7K, it accelerates like a modern bike, very quickly indeed, compared to my stock K0. Cheers, Terry. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Sam Green Racing

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #29 on: September 16, 2008, 10:01:18 PM »
I'll treat your last post with the contempt it deserves :-X :-X :-X :-X :-X :P :P :P :P :P :P :P :P :P
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Offline MRieck

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #30 on: September 17, 2008, 04:47:17 AM »
 I didn't port Chris's head though it would have been my pleasure. ;)
Owner of the "Million Dollar CB"

Offline Sam Green Racing

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #31 on: September 17, 2008, 12:13:15 PM »
And you would have done if I had had my way and the build ;)

Sam. ;)
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Offline lordmoonpie

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #32 on: September 17, 2008, 12:22:26 PM »
And you would have done if I had had my way and the build ;)

Sam. ;)

I gotta say in Sam and Chris's defence that film of racing and sprinting always makes the bike look slower than it really is. I have some video of me flat out in top on my old classic ducati when I was a mere slip of a lad. OK it was geared for around 110 tops but even so, on seeing the film my Mum fell about laughing at how slwo I was going. She stopped when I said it was about a ton up! The tale of the tape shows Chris is pretty darn quick on that bike over these parts, where even the straightline sprints have camber and gradient!  ;D
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Offline Sam Green Racing

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #33 on: September 17, 2008, 04:08:28 PM »
Stick that in ya pipe and smoke it ;D ;D ;D ;D ;D ;D ;D ;D

Sam. ;)
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Offline 75750SS

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #34 on: September 17, 2008, 05:11:38 PM »
So... jerimiah797 does that mean you're selling your stock carbs?
I call dibs first.

Offline Terry in Australia

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #35 on: September 17, 2008, 06:17:17 PM »
I didn't port Chris's head though it would have been my pleasure. ;)

Aha! If I'd known that Mike, I wouldn't have asked in the first place, no wonder that dog of a thing sounds like a WW2 BSA M20 running on Kerosene, and accellerates like a sloth on prozac, it's all show and bugger all go!

Now my superior K1 "Kruise Missile", with it's Mike Reick stage 3 "Superhead" and Megacycle 125/75 race cam, on the other hand, propels me down the road sooooo fast, that if I open my mouth to scream it turns me inside out like a smelly sock! ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Sam Green Racing

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #36 on: September 17, 2008, 07:02:27 PM »
 ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D ;D
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
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Offline Retro Rocket

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #37 on: December 29, 2008, 06:17:19 PM »
 Someone mentioned earlier the "ultra rare 31mm race kit Keihins with the ticklers" Can anyone tell me more about these carbs and what they might be worth? And on a 1000cc kitted bike would the newer 31mm smoothbores be a better option than the 29's ?

Cheers ..Mick
« Last Edit: December 30, 2008, 03:00:02 AM by retro rocket »
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Offline SOHC4 Cafe Racer Fan

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #38 on: December 29, 2008, 06:50:11 PM »
I have 29mm on my K7.  It's noticeably increased the performance (responsiveness, power, smoothness, warm up time) on my bike.  Once I get my new exhaust (Carpy's reproduced Yoshi 4-1), I expect there to be even more available power. 
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Offline Retro Rocket

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #39 on: December 30, 2008, 02:27:42 PM »
Quote
Someone mentioned earlier the "ultra rare 31mm race kit Keihins with the ticklers" Can anyone tell me more about these carbs and what they might be worth? And on a 1000cc kitted bike would the newer 31mm smoothbores be a better option than the 29's ?


Anyone ?
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Offline Sam Green Racing

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #40 on: December 30, 2008, 03:28:07 PM »
have you got lots of money ;D ;D ;D ;D ;D ;D
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Offline Retro Rocket

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #41 on: December 30, 2008, 03:43:45 PM »
Quote
have you got lots of money
No definitely not lots of money, but i have a very good set of these carbs and was after info. ;) Terry has already told me a bit but i was interested to hear what anyone else had to say.

Mick
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Offline Sam Green Racing

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #42 on: December 30, 2008, 04:38:13 PM »
Most racers don't bother with them, they only come up for sale when they are worn out.
People building CRs to original specs tend to push the prices up, the same applies to rev counters.

Sam. ;)
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Offline RRRToolSolutions

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #43 on: December 30, 2008, 06:05:15 PM »
I should have attached these photos back in September when this thread came up.

These are photos of Honda's stock "28's" and the CR29's, I'm telling you - there is no comparison -

Gordon





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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #45 on: December 30, 2008, 07:50:30 PM »
Thanks Sam, yep that's the ones  ;D Mine came with an "RSC" race kit that was originally installed on my bike, it also has RC rods and crank, stage 3 head, high performance gearbox, barnett clutch and piles of other goodies. I was just looking at some other stuff that came with it and i found an RSC catalogue a Yoshimura Catalogue  a Moriwaki catalogue and an Action 4's catalogue....all from the seventies....kinda cool eh... ;)  I will be putting the carbs on E-bay soon and i have a pile of jets and quick action throttle and stuff to go with it.

Cheers   Mick
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If You can't fix it with a hammer, You've got an electrical problem.

Offline Ricky_Racer

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #46 on: December 30, 2008, 08:06:21 PM »
Mick, I've got a couple nice sets of CR31's and could really use jets. If you decide the jets won't add substantially to your eBay sale, let me know if you want to split them off separately. Thanks!  RR
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Offline Retro Rocket

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #47 on: December 30, 2008, 08:25:26 PM »
Are they the earlier 31's like in the pics on the previous page? If so i'll have a look and see what i have. I was lucky enough to get all the spares with this bike as well {drag bike K4}, its all in boxes so when i get to go through it all i will let you know what i have.

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

Offline swedee76

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #48 on: January 04, 2016, 02:51:22 PM »
I bought a cb900 and there were allready a set of cr carbs on it. How or if where can I check the size on the carbs?

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Offline Terry in Australia

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Re: Anyone with Keihin CR Roundslide carbs on their CB750?
« Reply #49 on: January 04, 2016, 03:17:10 PM »
I can't remember if they're marked externally with the bore diameter mate, if you really want to know, you will probably need to take them off and measure them with an internal micrometer or vernier caliper. Cheers, Terry. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)