Author Topic: Throttle response & porting...  (Read 2783 times)

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hangtime

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Throttle response & porting...
« on: July 20, 2006, 03:29:09 AM »
Howdy again,
My cylinder is back after new plating and I was wondering about porting. My first priority with this motor is good throttle response. Throttle response and bottom end are sometimes confused and I need to clarify which I am shooting for. I always spend a lot of time jetting my bike and clearly remember that one time I had my CR250 jetted properly. What I think I appreciated most was the great response at any throttle position. If I had to choose one over the other I would probably take low/mid over mid/high.

Thanks and with a few more posts I'll start posting pics.

Offline Arigato

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Re: Throttle response & porting...
« Reply #1 on: July 20, 2006, 03:58:22 AM »
Check the jetting chart in the maintenence forum.  I've had the best luck with a ported cylinder and my carb bored to 41mm.  The cylinder side of the carb is then knurled which atomized the fuel better.  Very, very snappy.

Offline KXcam22

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Re: Throttle response & porting...
« Reply #2 on: July 20, 2006, 08:20:47 AM »
Look in Doordies Gallery. He has some pics of ported intakes. I did mine and it increased the snap nicely.  Jetting, reed spacer and Gnarly pipe are also must haves. Hope this helps. Cam.

hangtime

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Re: Throttle response & porting...
« Reply #3 on: July 20, 2006, 10:13:40 AM »
Thanks for the good information.
I was thinking about sharpening the "knives" I think they are called, at the bottom of the cylinder. And going with the reed spacer also. This seems like something I could do on my own, but do you all think it would be a step in the right direction i.e.. throttle response and bottom end power?

Offline KXcam22

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Re: Throttle response & porting...
« Reply #4 on: July 20, 2006, 05:34:09 PM »
Sorry but I forgot one key thing. Reeds!  I use the dual stage Boysen which increase the throttle response quite a bit (for cheap).  The Vforce may be even better but I haven't tried them yet. Cam.

Offline doordie

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Re: Throttle response & porting...
« Reply #5 on: July 20, 2006, 08:43:05 PM »
Vforce+powernow and "clean-up" intake from flaws, and take time to try different
jettings/needle.A good trued crank makes a huge different. :wink:
Iceroad champion 2006,still 2007,even 2008 without a single race!

Offline doordie

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Re: Throttle response & porting...
« Reply #6 on: August 01, 2006, 09:27:29 AM »
Wrong word,not Powernow,should be Powerblade partnr PB02 for a KXX(hate to spell it) :-P 125 SX,d**n orange coloured thing :-D
Iceroad champion 2006,still 2007,even 2008 without a single race!