• Enter the March CB750 Supply gift certificate giveaway! It's easy... Click here, post something, and you're entered into the drawing!

Keihin CR carbs for my CB750 Sevenfifty RC42

Messages
4
Reaction score
0
Points
1
Location
Poland
Hi All.
First of all hello to all CB750 users and riders ;)
New here - will introduce myself then - coming from Poland, riding Hondas since 20 years - my first bike CB450s still by me ;)

Now riding also a CB750 from 2001 - turning it into cafe racer. This is how it looks now:

1.jpg

I want to use Keihin CR carbs and K&N pods.
One thing that I might need here - maybe somebody already did that kind of carbs change and can help with jetting of CR carb, just to have something to start from.
I want to use CR29.

Thank You all for Your help.
regards
Pawel
 
Most here would have used Mikunis in that size.................CRs in that size are rare. A bit small as well.
 
If its a stock motor cr29 are just about right for good driveability. The CR carbs flow and atomize very well, no need to go too big. CR's not rare at all in this size, it is a very common size for CR carbs, Dynoman stocks them.
 
Thank You guys. I already have the CR29 and that's a stock motor so shall be ok. I would just need a hint with jetting, needle position etc. to start with adjusting.
Stock it has main #110 on outside cylinders and #112 on inside, slow #35. Starting with same sizes would be right ?? And of course CR's have Air jets... What size here ?

regards
 
Where did you get them from? I would call Buzz at Dynoman, when they sell the carbs they ask you specs on your motor and they prejet them to get them "close". Too many things affect jetting to say what your motor will need. Exhaust, motor condition, temperature, elevation, fuel quality, etc all affect jetting.
 
I got them used from Germany...

My CB has a stock engine, 4-1 exhaust (open through), motor is in a good condition - it has only 19000km on. I'm riding only 15 deg. Cels. up at 100m elevation - we 'got it flat here by the Baltic sea ;) Fuel in Poland is not the race quality but also not so bad, I'm riding always 98 octane...
If you need something more - I'll be delighted to answer any question - Your help is highly appreciated ;) If You can ask Your colleague about some details I'll be very thankfull.

regards
Pawel
 
It would pobably be best if you called or even just emailed dynoman. Buzz is very helpfull and always willing to answer questions. Just for your information the 29 cr's come from the factory with 120 mains and 60 slow jets and the needle in the 4th position. If I was to do it myself I would start at those and adjust as needed.
 
By rare I meant rarely used here, they are around but most have much more tuning info with Mikuni in that size as they sold like hotcakes. Could try talking to Sudco, they know lots of custom setups for different engines to start off with.

http://www.sudco.com/catalog38.html#140

Let it load, there's like 500 pages there. CR parts start at page 122. There is a Keihin tuning section much further back.

Those people will know more about carb swaps than anyone on the planet as they do lots of really deep racing work.
 
Last edited:
Back
Top