Which Carb?

[cardinalhvac]

My son races TT here in MO and we are trying to figure out what the best carb choice is for his DRX 90 which has ported cylinder and high compression head. it currently has a 20mm keinen carb on it and runs very strong. what benefits will we have going to a 24 or 28?????

[jread14]

I have been told by a very good engine builder that the PE 24 is the best carb for a built 90... It should give you more top end than what you are getting today with the 20mm carb. JR

[bulldogfallon]

PE24 is a better MX choice IMO and Jason we both share the same reference for the builder :)


Now that being said, the 28mm carb may provide some better areas of performance for TT racing when your need more top speed than all around performance (Is this correct TT guys)


The 20mm is absolutely too small for your application....The 24mm would be a very safe option, but the 28 could perform better at some areas than the 24mm.

[ukguy]

this may not be of any use but when we build our MX engines back to back carb tests,

the 24mm power jet was very good and gave good power, the 28mm was better slightly gave about half a BHP more and good shot in the torque, the 30mm was also excellant and gave another half a BHP over the 28 and another gain in torque.

so i assume the 24mm and 28mm set up correctly would suit your purposes a little better.

[jread14]

Originally posted by bulldogfallon
PE24 is a better MX choice IMO and Jason we both share the same reference for the builder :)


Now that being said, the 28mm carb may provide some better areas of performance for TT racing when your need more top speed than all around performance (Is this correct TT guys)


The 20mm is absolutely too small for your application....The 24mm would be a very safe option, but the 28 could perform better at some areas than the 24mm.

Yeah, What Gary said!!! :D

[THARNESS]

We used to race a lot of the TT nats with a built 90 cvt with a 28 khein. It ran good on top but I could never make it respond off the bottom like I wanted it to. One day after many jetting and testing runs with no improvement I pulled the stock carb(24 mikuni) off of my son's KX65 dirtbike for a try. It was a huge improvement on the bottom without any noticeable loss on top. So I guess I said all of that just to say this....... Go with the 24.