04-15-2010, 02:42 AM | #1 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
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XR200 / XR200R Camshaft
Since the question has come up a couple of times, I thought I'd share the cam specs I found today. My son and I were tearing down another donor engine for his '83 XR200R that's under construction, so we took some measurements.
We measured a 1980 XR200 and a 1983 XR200R cam, and found that they were within 0.001" of each other. The cams measure 0.0270" intake and 0.0255 exhaust at max lift (I don't have a degree wheel for duration measurements). It seems that the only difference between the two engines is the high compression piston in the XR200R. Guess which piston we'll be using? :wink: Maybe this info will benefit a Lifan China Rider.
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04-15-2010, 08:55 AM | #2 |
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Location: Altamont, Kansas
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Maybe I should take the lifan engine apart and measure its cam.
Allen
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04-15-2010, 10:31 AM | #3 | |
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Quote:
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04-15-2010, 11:00 AM | #4 |
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I should add that I'm not certain if the cam in the '83 XR200R is correct for that year; it had a plain XR200 head on an otherwise XR200R engine. All I know is that one of the cams I measured is from a plain XR200, and the two cams are virtually identical.
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04-15-2010, 11:32 AM | #5 |
Join Date: Mar 2009
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Kato asked about the measuring process in another thread, so here's how I did it. I used a dial indicator and magnetic base, and I set the zeroed dial indicator tip as close to the centerline of the cam base circle as I could. I cycled the cam in both directions to ensure consistency, and I didn't disturb the adjustments when I swapped in another cam for comparison.
Dial indicator: Magnetic base (I had a hard time getting the magnet to stick to the aluminum, hence the clamp ):
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04-15-2010, 12:11 PM | #6 |
Join Date: May 2007
Location: Altamont, Kansas
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So I will need to pull the valve cover off this engine and get some details.
Allen I can do that. FIY, I found an 86 xr200 needing an engine. :wink:
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04-15-2010, 10:53 PM | #7 |
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That is some remarkable work! And very interesting. How can a different piston change the compression?
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04-15-2010, 11:54 PM | #8 | |
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04-15-2010, 11:56 PM | #9 |
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OK, sure is interesting!
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04-16-2010, 02:12 AM | #10 | ||
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Quote:
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04-16-2010, 02:21 AM | #11 | |
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Location: Surrey, B.C., Canada
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Re: XR200 / XR200R Camshaft
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I seem to remember a burnt valve from one of those motors? Was the burnt valve from the HC piston motor? I'm not sure, but if you went with the HC piston you may want to ensure the valves were the same and not a different material or design. (More heat) |
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04-16-2010, 02:36 AM | #12 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
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Nope, no burned valves in these motors, in fact the valves on this latest motor look really good. Since it was a matched set, I'm gonna run the new head, cylinder, piston and valves.
You might be thinking of an old Toyota I had.
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Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer |
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04-16-2010, 02:40 AM | #13 | |
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Location: Surrey, B.C., Canada
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No matter, I'm sure you have your engine rebuild well under control, I can't wait to race Sam on the newly built W&G + Son Honda. Yamaha will prevail. Go Team Blue! 8) |
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04-16-2010, 08:46 AM | #14 | |
Join Date: Oct 2007
Location: SW Ontario
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Re: XR200 / XR200R Camshaft
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04-16-2010, 10:53 AM | #15 |
Join Date: Mar 2009
Location: Sardis, BC, Canada
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I was waiting for your input, suprf1y. I don't think that we have any other cam grinders on here.
Have you ever played with the mechanical advance mechanism on an old XR200R? I figure that I should be able to connect my timing light and check the dynamic behaviour.
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