Author Topic: Types and makes of replacment carburetors for the 750.  (Read 11432 times)

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Offline 754

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Re: Types and makes of replacment carburetors for the 750.
« Reply #25 on: February 12, 2008, 07:47:25 AM »
The difference is in the manifolds, I have a splayed one on the bike and shorter  rubber intakes, so I have more clearance.

Straight, you dont have to notch sidecovers, splayed you do.

As any speed equipment the pain has to justfy your gain. just like you know the stiffer spring are going to beat on your cam but you decide it is worth it for the gain..it is gonna cost sometimes..like adding a second 10 lb disc to the front of our bikes..

Terry how did you end up with so much speed equipment you dont like?? Did you ever try your Dellorttos?
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Offline Terry in Australia

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Re: Types and makes of replacment carburetors for the 750.
« Reply #26 on: February 12, 2008, 06:19:09 PM »

Terry how did you end up with so much speed equipment you dont like?? Did you ever try your Dellorttos?

Well, I bought the Dellorto's from a car guy, then found the only NOS manifold in Oz, and Daniel was nice enough to show me a pic of his linkages. I never ran them though, the weight really put me off, and Mike Rieck advised me to buy the CR's to suit the head he built me.

I did get to ride a Dellorto equipped CB750 based 1200cc bike, (built by Rex Wolfenden, Australia's premier Honda CB750 builder and racer) and it went extremely well, but of course, considering the engine mods it'd be hard to tell how much difference the Dellorto's made, and the new owner replaced them with Mikuni flatslides shortly after buying it, but I don't remember why.

I'm a big EBay fan, and I discovered quite early that there are "performance parts" out there that if bought cheaply enough, can generate enough money for more desireable items. The Webers, Dellorto's, ARD and RC Magneto's etc can generate quite a lot of money as they're very popular with the retro chopper guys in particular, because they do look cool. I've still got 3 ARD Mk2 magneto's for Kawasaki Z1's, but the Kawasaki guys aren't as interested in them as the Honda guys are, so they're harder to move. I must machine them up to fit CB750's.

The CR's are very well priced at around 700 bucks a set brand new, but you can normally pick up the webers or dellorto's a fair bit cheaper, and now that guys like Daniel are selling new rubbers for them, they are even more desireable. If I see another set of Dellorto's (or Webers) I might try them out on the 1060 engine, as light weight won't be a #1 priority. Cheers, Terry. ;D
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Offline City Boy

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Re: Types and makes of replacment carburetors for the 750.
« Reply #27 on: February 17, 2008, 05:56:14 AM »
Well boys,this discussion has gotten quite WEIGHTY!I only have experience with vm 29 and RC webers,the webers were clearly superior in performance.The engine had a completely different persona,also sounded more like a Cosworth V8 than a Honda at WOT.Given the chance,I would install them on my 1100F without hesitation.ROCK ON boys.
'52 Kiekhaefer Mercury Rocket Hurricane KG4H
'70 750/RC 1000 Original Owner
'83 1100F

Offline Soos

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Re: Types and makes of replacment carburetors for the 750.
« Reply #28 on: February 17, 2008, 08:05:44 AM »
EXCELENT information all!

Has anyone tried any of these carb setups on a 650?

As a side note - In your opinion, what diameter venturi is needed for a given CC displacment for a 750?
The 736cc stock of a 750 for example, was it choked by the carbs?
Would say 29mm be better suited for stock, and 31mm or so for 836?
Is there a ratio of cc displacement vs venturi diameter for optimal power/performance?

l8r
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Offline mkramer1121

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Re: Types and makes of replacment carburetors for the 750.
« Reply #29 on: February 17, 2008, 03:11:43 PM »
Check out satanicmechanic.org, lots of good info...

billybobobrain

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Re: Types and makes of replacment carburetors for the 750.
« Reply #30 on: July 16, 2008, 12:19:31 PM »
has anyone coverted 82 cv carbs onto a early 750?

Offline MCRider

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Re: Types and makes of replacment carburetors for the 750.
« Reply #31 on: July 16, 2008, 02:06:28 PM »
EXCELENT information all!

Has anyone tried any of these carb setups on a 650?

As a side note - In your opinion, what diameter venturi is needed for a given CC displacment for a 750?
The 736cc stock of a 750 for example, was it choked by the carbs?
Would say 29mm be better suited for stock, and 31mm or so for 836?
Is there a ratio of cc displacement vs venturi diameter for optimal power/performance?

l8r

Its not an issue of cc to venturi size due to different carb efficiency, and the volumetric efficiency of your set up, head, cam, pipe. Also not all venturis are round, some are oval, so like monitor screens, one man's 19" is not anothers.

Trial and error, talk to people who have been there.
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Offline City Boy

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Re: Types and makes of replacment carburetors for the 750.
« Reply #32 on: July 16, 2008, 04:37:47 PM »
Hi guys.I have experienced a direct comparison between the 29 smoothbores and the DCOE40-32 on my 1000.I have none with the CR's so I don't know how they would stack up.I road raced my machine a few times at Mosport Park ,a very fast circuit that gives ample opportunity for winding the living snot out of whatever you are on.The difference was like night and day in the Italians favour!Tuning did take longer and was more costly,the weight issue didn't bother me .I used the upper air cleaner mounts bent 90' and fitted rubber isolation studs to the carbs.The machine sits idle right now,I'm having too much fun on my 1100F,but I would put webers back on in a New York minute if I get the chance and I have any Lira.The comparo to me was valid as no other changes were made to the machine.       Rock On
'52 Kiekhaefer Mercury Rocket Hurricane KG4H
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'83 1100F

Offline .RJ

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Re: Types and makes of replacment carburetors for the 750.
« Reply #33 on: July 17, 2008, 05:31:55 AM »
Has anyone fitted a set of flatslides on a CB750?  Would they still need to be ~29mm?