Smacaroni, on 18 July 2012 - 04:01 AM, said:
I'm going to look at an XR100 motor on Friday. The guy says he can't find a serial number, but I bet it's just covered in gunk.
Since I'm going to look at this to buy it, I don't want to have to leave and come back or fumble through stuff on my phone attempting to identify the year or version of the motor.
My research says that all the XR100 motors will have a serial number beginning with HE03E- and I've found that -52... is 1983, for instance. Can anyone tell me what the rest of the serial would indicate years of major changes? I realize there isn't much, the XR100 was a really reliable motor, so Honda didn't mess with it.
Perhaps serials beginning in 91, 95 and 2001?
And is the serial always near the shift lever or did Honda stamp it in other places too?
Serial number is only located by the kicker. Serial number progression only indicates year.
These engines utilize plain bearings for the cam, bad news if it was laid over on the left and let idle while "Johnny" licked his wounds. Heads are not cheap, if you see anything sketchy walk away.
Cam chain, crank and cam chain sprocket wear, tensioner wear is very common, damage left side cases are common due to piss poor drive chain guide.
Early versions (Pre 1985)
had a shorter kick shaft than later
had valve seals on both valves.
1985 - 1992 virtually unchanged,
1992 and up had CDI ignition, early versions can be updated to CDI but it's not perfect.
Edited by theraymondguy, 18 July 2012 - 03:01 PM.