Carburettor Jet Size Info Please

[mattbenselin 0]

Hi all,

 

Some help needed regarding jet size to upgrade to on my bike carbs. As per title they are Keihin CV 40mm carbs removed from a Kawasaki ZX-9R.

The engine they are to be fitted to is a 1.9 8v which has had head work, cam upgrade, increased CR...

I don't know what size they are as standard but I have heard that maybe weber jets will fit right in or I will have to drill out the standard ones.

 

Any help on this would be appreciated, thanks,

 

Matt

[swordfish210 20]

start off with a 200 main jet and work up from that. Do you have a lambda meter?

 

edit: dont bother with buying new jets just drill them out...much cheaper

Edited November 26, 2008 by swordfish210

[mattbenselin 0]

The car will be set-up at home (ie it runs with the jets in at moment), but will be taken to rolling road for full set-up. So you think to try 200? How much is that (thick moment!)?

 

Matt

[swordfish210 20]

put a decimal point in after the first number and you have a measurement in milimeters i.e. 200 = 2.0mm. Have you set the rest of the carbs up allready?

[mattbenselin 0]

They were removed from an 8 valve 1.9 and are to be fitted to an 8v 1.9. The guy said they ran ok and could be used but were not giving their full potential because of incorrect jetting. they are not on the car yet so can't be sure how well they will work, but wanted to try sort out the jets before they go on.

 

Matt

[swordfish210 20]

Sounds ok then. First thing to do is to balance the carbs because that will sort the idle speed out. Then turn the idle jet screw to 3 1/2 turns out. That should give you a good amount a fuel at idle. You want to get the carbs so they are just slightly rich at the top end of the rev range but too rich at the bottom end. Once you have that you can then adjust the needles so that they will sit lower in the jet which will lean out the bottom end of the rev range. This is what i'v done with my carbs and they run pretty darn well