Topic: 29 smoothbore to CB750 carb adapters. need application help?

[Don R]

 There is a thread going on in sohc4 bikes about the recently unobtanium Sudco VM29 mikuni to cb750 adapters.
 I sent and got a return email from Bill at UPP racing and he said they can still make the adapters and there is no minimum order. I have a set of their urethane ones and they seem a lot more substantial than the old rubber ones.
 I didn't get a price, the last set of rubber ones that I got from Z1 Ent. ended up around $200 taxed and shipped. I'd like to think they could end up at that price point or less.

[Don R]

 Bill from UPP replied that Sudco never gave them any information on the cb750 to 29 smoothbore Mikuni adapters. He would like some help with applications etc. so he can add them to the catalog.
  As far as I know they adapt VM29 Mikuni smoothbore carburetors with Kawasaki/Suzuki spacing to Honda 1969 through 1978 CB750 K and F models. Does that sound accurate?
  I'm thinking other Mikuni carbs would also fit the adapters but I'm not sure enough to add that.
  I might also suggest that he look at making the standard Honda intake manifolds in urethane, I'd buy a set or two for sure. No rubber pulsing or sagging and the correct clamps could fit.

[willbird]

Bill from UPP replied that Sudco never gave them any information on the cb750 to 29 smoothbore Mikuni adapters. He would like some help with applications etc. so he can add them to the catalog.
  As far as I know they adapt VM29 Mikuni smoothbore carburetors with Kawasaki/Suzuki spacing to Honda 1969 through 1978 CB750 K and F models. Does that sound accurate?
  I'm thinking other Mikuni carbs would also fit the adapters but I'm not sure enough to add that.
  I might also suggest that he look at making the standard Honda intake manifolds in urethane, I'd buy a set or two for sure. No rubber pulsing or sagging and the correct clamps could fit.

Yes indeed the standard ones would be an excellent idea for sure.

Bill

[Jerry Rxman Griffin aka MuthaF'er]

Don, you having me thinking OH NO haha

I wonder if his quality would be better than what's available for the CB750F2/F3?

[scottly]

  As far as I know they adapt VM29 Mikuni smoothbore carburetors with Kawasaki/Suzuki spacing to Honda 1969 through 1978 CB750 K and F models. Does that sound accurate?
 

The '77-78 F2/F3 had larger outside diameter spigots on the heads than all the other 750s, so would need different adapters.

[Don R]

 I only got the one set of their Mikuni adapters but I really like them. They feel more solid than the rubber reproductions. I have not approached them about making stock replacements, but he would need a set of perfect ones to work from. I think there would be three or four applications. K0, K1- up, F2 and A?

[willbird]

I only got the one set of their Mikuni adapters but I really like them. They feel more solid than the rubber reproductions. I have not approached them about making stock replacements, but he would need a set of perfect ones to work from. I think there would be three or four applications. K0, K1- up, F2 and A?

The OEM are still avail on Ebay, not inexpensive by any means, and not sure what the last day was that Honda made one.

[Don R]

 I've read the new Honda ones may have been made from old hard ones and are smaller OD. causing the clamps to not tighten enough.

[Jerry Rxman Griffin aka MuthaF'er]

  As far as I know they adapt VM29 Mikuni smoothbore carburetors with Kawasaki/Suzuki spacing to Honda 1969 through 1978 CB750 K and F models. Does that sound accurate?
 

The '77-78 F2/F3 had larger outside diameter spigots on the heads than all the other 750s, so would need different adapters.

Yes, those were 2 year specific for the 77/78 CB750F2/3 AND the work on the Mikuni RS34 adaptation applications

[Don R]

 OK good to know, I'll pass that along. 

[Jerry Rxman Griffin aka MuthaF'er]

The ones that are available have issues. Poor quality. They crack quickly plus whoever makes them makes one shorter than the others. Cruisin shut me off, as he does, if you mention anything negative to him. haha

[willbird]

I think a set designed to mount one of these would be super cool :-).





Bill

[Don R]

 What is that EFI rack off of? And what's the diameter and spacing?

[willbird]

What is that EFI rack off of? And what's the diameter and spacing?

CBR600RR.

One source google gave me said 74-76-74, 38mm spigots I think and at some year they went to 40mm. Sketchy info suggests 30mm butterfly, I have a set but they are at home and I am at work ;-). Not a big deal to adjust the center spacing wider.

I'm seeing CB750K SOHC  listed as 80-100-80 spacing

[Don R]

 I see a mechanical fuel injection on FB marketplace, it was on a 1200 Suzuki.

[willbird]

I see a mechanical fuel injection on FB marketplace, it was on a 1200 Suzuki.

There is lots of stuff avail, some of them are nice enough to include almost all of the sensors needed as well as an idle air motor setup. But the universal problem is that the smallest 4 cyl bikes they were made for demand a LOT of air to create the HP they produce at their peak HP RPM. This creates a plumbing problem. Some older threads here the authors somehow got those HUGE spigots shoe horned into an OEM honda rubber isolator but I'm not seeing how :-). The smaller I4 sportbikes were mostly for countries not on the same continent I currently live on :-).

This one might be interesting..
24 KAWASAKI NINJA ZX4R THROTTLE BODY BODIES



Looks like it is drive by wire maybe but that is not outside the ability of the average machinist to rework :-). I had not went that "new" looking for stuff. That bike is 76-79HP 57kw-59kw

Bill

[Don R]

 I got a set of Vintage cb750 carb rubbers for K0, they seem very solid and appear correct. I have not tried a test fit of clamps or on a cylinder head yet. I really can't imagine them pulsing.

[willbird]

I got a set of Vintage cb750 carb rubbers for K0, they seem very solid and appear correct. I have not tried a test fit of clamps or on a cylinder head yet. I really can't imagine them pulsing.

I bought the OEM parts for my CB750K2 from Ebay, they are really solid..not sure what the last day/year was that Honda actually made one.