Crankcase transfer port-Anyone ever cut one?

[Bruce CurtisMember]

Was reading an article by the master of 2T tuning Eric Gorr, and he suggested on the Kawasaki KX 60/65s you drill a hole in the rear of the piston, now this I have done dozens of times on many brands, creates a Piston-port effect and can create a real torque hit in the midrange of the power, but he went a step further and recommended cuting a “crankcase transfer” slot or port across the rear skirt of the actual bore liner to aid transfer of compressed charge to the transfer ports that run up to the intake area. Now while i can see how this would creat a better transfer flow my question is “has any old Bulls ever done this before or heard of it”?.

Bruce

[drewMember]

all new to me Mr Blue!! but all i know about 2T’s is if they’re not self mixing/ injected you have to pre mix your fuel/oil. :blush:

could you post up some pics or links to what you have done and what Eric suggests?

what other brands of bikes dose it work in??

i reckon i could chew your ear for a month learning what can be done with the 2T engines and still only scratch the surface.

[Bruce CurtisMember]

Well i spent a few hours today cleaning up the worst cast barrel I have ever touched, the ports were all wildly mismatched, casting dags all over it, so me and the die grinder and a dremel played for a while and basically blueprinted the intake/exhaust and then I matched the exhaust and might do the cases yet.
Am going to skip the piston/port mod on this one, he doesn’t need any more topend, but after carefully scrutinising the whole port relationship I ended up cutting two new transfer ports/channels into the bottom of the rear transfers, should assist in midrange airspeed and give better throttle response.

Might advance the timing 1-2 degrees and space the pipe out a few mm to give it a longer header section to improve torque at lower-mid as well yet, only prob is since I sold my lathe I might have to scrounge something up.

Told the young bloke she’ll be brunning tomorrow arvo, stronger and sweeter

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