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New carbs
Posted: Thu Jan 14, 2010 10:18 pm
by jkotsi
I have seen that TIMS offers CRS and FCR carb kits for the CBX. Is there a production bike running 35mm FCR's that are jetted close to the CBX requirements?
The GSXR 1100 93-95 FCR's work best with the CB1100F, I am looking for something similar for the CBX.
Once you have the carbs the spacing and intake manifold can be worked out, jeting will add to the conversion.
Jim
Posted: Fri Jan 15, 2010 11:06 am
by Jeff Bennetts
Re: New carbs
Posted: Fri Jan 15, 2010 7:43 pm
by alimey4u2
jkotsi wrote:I have seen that TIMS offers CRS and FCR carb kits for the CBX. Is there a production bike running 35mm FCR's that are jetted close to the CBX requirements?
The GSXR 1100 93-95 FCR's work best with the CB1100F, I am looking for something similar for the CBX.
Once you have the carbs the spacing and intake manifold can be worked out, jeting will add to the conversion.
Jim
If you measure the stock inlet tracts you will find the real limitation. Carbs work on the venturi principal. To be effective they have to be the "vena contracta". Quite important for "street" setup...
Re: New carbs
Posted: Fri Jan 15, 2010 9:22 pm
by spencer
alimey4u2 wrote:If you measure the stock inlet tracts you will find the real limitation. Carbs work on the venturi principal. To be effective they have to be the "vena contracta". Quite important for "street" setup...
Larry, you got my interest when I read the first two sentences, but I don't understand the punch line. Can you translate "vena contracta" for me?
Posted: Fri Jan 15, 2010 9:33 pm
by Terry
Posted: Fri Jan 15, 2010 11:22 pm
by 415ZR1
Is TIMS offering FCR's? Could only find CR-S on the TIMS website.
Here's a set of original unused VM29 Rick's Tricks. My 10 y/o Olympus is dying on me, so pardon the poor quality pic...
Re: New carbs
Posted: Sat Jan 16, 2010 3:40 am
by alimey4u2
spencer wrote:
Larry, you got my interest when I read the first two sentences, but I don't understand the punch line. Can you translate "vena contracta" for me?
It's all to do with signal (good vacuum) at the jet.....Some people cheat themselves by fitting a filtration system. This increases the negative but that cannot be kept in calibration. The more the filter clogs, the greater the signal...
The point of lowest-pressure and highest velocity that's located 0.030 inch below the venturi's throat (minimum diameter). The center of the discharge nozzle or the trailing edge of the booster venturi is placed at the vena contracta
Note the term "minimum diameter"....The carb venturi needs to be the minimum diameter, not something else along the flow path....
