Anyone Familiar With Keihin CR Special Carbs?

I bought a used set of carbs and I'm not sure what size they are. The PO thought they were probably 33's but the box said 37mm. I got them today and the intakes measure 35.5mm at the very end (where they go into the rubber boots). Here's the perplexing part: On the Keihins, the intakes are interchangeable for different motorcycles and they thread right into the carb intake throat. It's the adapter that measures 35mm while the carb intake measures 33mm. What size are these things? I'm just not familiar with Keihins.

Also, are there any markings that will indicate the size? Most mikunis have the size right on them. Thanks!

I didn't find any markings on my 29's... Just measured and ~ 29mm pending how tight I clamped my caliper

They come in sizes ranging 29mm, 31mm, 33mm, 35mm, 37mm, or 39mm so 36mm/37mm are out...

Are you measuring the inside diameter of the outlet or the outer diameter? Measure the inside...

OMR

They measure 35mm I.D. at the tip of the intake spigot - right where they clamp to the rubber manifold on the head. Here's the problem - when you unscrew that spigot, the other end measures 33mm I.D. and matches the carb throat, just inside of the threads. Mikuni's don't have removeable spigots like that so I'm not sure what's what. I think I have 33's or 35's. Each carb has a "33" ink stamped on them but I'm not sure if that's the size or not.

id say go with smallest point inside carb which seems to be 33mm

Survey says! 33mm :laugh:

I sent an inquiry to Sudco and they told me they are 33's if ink stamped "33". Sounds simple enough, but I wanted to make sure. Now I'm kind of bummed because I already have Mikuni 33 smoothbores and wanted 35 or 37 CR's. Not sure if 33's will be enough for 1260cc with oversized valves, .425 cams and ported head??

If anyone is interested in a set of 33 CR's or would take a partial trade toward 35's or 37's - please let me know. Or if you have 35 or 37 CR's for sale straight up, let me know.

My 33 smoothbores ran great before I changed to the 34 flatslides, so I just can't see spending extra money on the CR's unless they're bigger than my Mikuni's. Plus I already have lots of Mikuni parts and none for the Keihins.

79MKII wrote:

Survey says! 33mm :laugh:

I sent an inquiry to Sudco and they told me they are 33's if stamped "33". Sounds simple enough, but I wanted to make sure. Now I'm kind of bummed because I already have Mikuni 33 smoothbores and wanted 35 or 37 CR's. Not sure if 33's will be enough for 1260cc with oversized valves, .425 cams and ported head??

33s are more than enough for that 1260 on the street,my 1327 is running an old set of 33s smoothbores right now and it runs much better than it ever did with those damn 38s

PLUMMEN wrote:

79MKII wrote:

Survey says! 33mm :laugh:

I sent an inquiry to Sudco and they told me they are 33's if stamped "33". Sounds simple enough, but I wanted to make sure. Now I'm kind of bummed because I already have Mikuni 33 smoothbores and wanted 35 or 37 CR's. Not sure if 33's will be enough for 1260cc with oversized valves, .425 cams and ported head??

33s are more than enough for that 1260 on the street,my 1327 is running an old set of 33s smoothbores right now and it runs much better than it ever did with those damn 38s

Wow, I don't know why I didn't realize it before, but my brother has 33 smoothbores on his 1327 too. Always ran great. Maybe I'll just put the 33 mikunis back on and sell the CR's. Or are the CR's better in any way?

Can't really say which is better pending year of those CRs but one thing for sure I'm positive about.... these CRs are extremely easy to jet....

Hell if I can do it anyone can....

OMR

ive never dealt with the crs but in my experiance anyway the smoothbores are tempermental to deal with

Are the 33 smoothbores a good set of carbs once you get them sorted out? Or do they need constant tinkering? Ive got a set,but they need gone thru. Just wondering if theyre worth it, or if I should just Ebay them and get some RS34's

PM Sent How much? Some pics?
Cheers.Jeff