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38 mm carbs


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Neal

 
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38 mm carbs

Wed Jun 10, 2009 6:32 pm » Post: #1 » Download Post

Hi ,

I want to install a set of 38mm carbs on my mc21 . There is no tps on them . What do i do with the tps and the air solenoids .

Thanks for any info .

Neal
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Andy
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Wed Jun 10, 2009 6:43 pm » Post: #2 » Download Post

You can just remove the air corrector solenoids, but need to retain the TPS (unless you go F-III).

The TPS needs careful setting to get the best performance, and can really only be done on the dyno where you can measure the differences.

PJ38's aren't any better than NSR250 carbs though, and in most cases appear to be worse! One day we hope to persuade Racer38 to let us fit some NSR carbs to his NF5, just to prove a point! Smile
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Neal

 
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Thu Jun 11, 2009 11:25 am » Post: #3 » Download Post

Ok thanks for the info , i will leave alone until i have more info - knowledge .

Thank you .
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scottvor

 
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Thu Jun 11, 2009 10:58 pm » Post: #4 » Download Post

Neal, If you don't have any port work done to your cylinders, don't bother with this. My RS125 PJ38 carbs make much more power on my bike but my cylinders have modified porting and a 2mm overbore.

I measured the resistance from the TPS with the throttle open. I believe it was 5k ohms. I then removed the TPS from the MC28 carb body and carefully rotated it until the resistance was the same and then put a little RTV to hold it in that position and plugged it back into the wiring harness. My air solenoids are buried in a box in my garage.
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Neal

 
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Sat Jun 13, 2009 8:21 pm » Post: #5 » Download Post

Hi , thanks for the info . I have a race spec motor and a 300 topend kit . I will do the carb installation after i have run the 300 kit . I will do a back to back dyno run and report my results.

Thanks , Neal
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StephenRC45
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Sat Jun 13, 2009 9:12 pm » Post: #6 » Download Post

On the 300's the bigger carbs did/do help alittle but loose a fair amount of power and torque in the middle.

The stock carbs work well as though they are stated as 32mm their shape works much better than their size would indicate.
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