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CXR 230

Othen
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Othen
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Joined: March 6th, 2018, 2:23 pm

March 25th, 2018, 3:36 pm #1

Monty wrote:Look like its running lean judging by the colour of the header pipe, should not go blue like that if correct,

exhaust does look good, good luck with mot
You are right, the original carburetor is set up to run really lean. I did consider re-jetting it, but I thought I'd get the bike through the MoT before changing the unit for a Keihin PWK, which will fix the problem and allow some proper tuning (it came with a good range of jets).

I gave the bike a good check over this morn, let's hope all is well for the MoT test!
Last edited by Othen on March 25th, 2018, 3:38 pm, edited 1 time in total.
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Othen
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Othen
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Joined: March 6th, 2018, 2:23 pm

March 27th, 2018, 12:46 pm #2



The Keihin PWK carburetor is fitted, it was almost a straight swap for the original CV type item (I just had to change the throttle cable for a normal bike type). The bike seems to be running pretty well, it has got rid of the popping on the overrun and is running cooler (the original was set to run very lean to comply with the emissions requirements).

I'll take the bike out for a spin at the weekend and assess whether there is a genuine improvement in power and control.

Last edited by Othen on March 27th, 2018, 1:11 pm, edited 2 times in total.
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Othen
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Othen
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March 28th, 2018, 7:56 am #3

... afternote: The only issue with the new carburettor is that the fine adjustment (air and slow running screws) are on the left (inboard) side, making adjustment really fiddly. I had to raise the tank up about 6" (blocking it in place with a piece of wood) in order to get just enough clearance for a small screwdriver for the air screw. Fortunately the mixture was about right (I'd replaced the main jet with a 140) at 1.5 turns out and it just had to be leaned off slightly. I could adjust the slow running jet by hand with the tank in that position, bringing the tickover down to about 600 RPM.

Even though the fine adjustment was fiddly, I can't really say it was worse than the original CV carburettor which had the slow running adjustment (a simple lifter on the external throttle assembly) inboard, and no air adjustment.
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Othen
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Othen
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Joined: March 6th, 2018, 2:23 pm

March 28th, 2018, 8:00 am #4

... an afterthought: perhaps it would have been better for me to have put this thread in the 'Projects' rather than 'Introduction' section. If the moderator agrees perhaps it could be moved there?

On the other hand, the CXR 230 is a bit down market - so parhaps no one is really fussed - no matter, I still quite like the bike and have more or less the same thing as a Honda CRF 230L for under £1000!
Last edited by Othen on March 28th, 2018, 8:13 am, edited 2 times in total.
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Monty
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Joined: January 30th, 2012, 6:02 pm

March 28th, 2018, 1:12 pm #5

Thread split, keep up the good work as I've never played with a CXR 230, all good info
If it aint sharp I can play with it
My Utube Channel, lots of bike vids here. Subscribe if you likehttp://www.youtube.com/user/choppermark?feature=watch

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Othen
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Othen
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March 29th, 2018, 6:14 am #6

Monty wrote:Thread split, keep up the good work as I've never played with a CXR 230, all good info
Monty,

Many thanks for moving this for me, it makes more sense in the 'Projects' section (if I'd thought about it I'd have started it there in the first place.

I'm not sure how many subscribers will be interested in the 230, but I'll paste anything I think might be useful here.

Best wishes,

Alan
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Othen
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Othen
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March 29th, 2018, 6:47 am #7

I'll take a few photos of the original (CV) carburettor whilst it is still on the bench to show its limitations. The flat slide Keihin should be a far superior unit for a dirt bike...
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Othen
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Othen
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Joined: March 6th, 2018, 2:23 pm

March 29th, 2018, 10:42 am #8


... here you can see the butterfly valve - which is connected to the throttle cable, but there is no mechanical connection to the flat slide. Good for fuel efficiency (because the fuel:air ratio remains fairly constant) but bad for throttle response (due to the lag between the butterfly valve and slide moving) and power output (due to the obstruction caused by the valve itself)...
Last edited by Othen on March 29th, 2018, 12:03 pm, edited 2 times in total.
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Othen
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Othen
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Joined: March 6th, 2018, 2:23 pm

March 29th, 2018, 10:43 am #9


... and here is the inlet side with the flat slide, which has no mechanical connection to the throttle cable. This arrangement is good for efficiency on road bikes and for controlling emissions, but not what is required for a dirt bike (good throttle response and power output at the expense of fuel consumption and emissions).

The Keihin PWK I have fitted should be a much better solution for the 230 (we'll see how it turns out).
Last edited by Othen on March 29th, 2018, 12:44 pm, edited 2 times in total.
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Othen
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Othen
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April 1st, 2018, 8:23 am #10

Having succeeded with my video of the Suzuki B120 running I've done the same with the CCM:

https://1drv.ms/v/s!Ask6E_1jz4xIskfv2MiRl1NPoLe3

I'm quite pleased with the way this little bike came out. My son and I will be taking it to our other house in Norfolk to try it out off-road today.
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