79 xl/xr 250 engine differences

[Andrew L]

Could someone please enlighten me of what are the main difference between a 1979 xl250 engine (20hp) and the xr250 version (30hp) of the same year,  I suspect cam carb but are the heads ports etc different as well Cheers Andrew

[Colin Jay]

I would say that the main difference is the advertising blurb!

I worked for as a mechanic for a Honda dealer in the 1980's and still have a large collection of parts and service manuals/fiche. From the parts lists, the head and valves have the same part numbers.  The camshaft is different, as is the carbie and exhaust. I did have a XL250SB back then with the XR camshaft, 305 big bore kit and an after market exhaust. Only minor alterations were required to the carbie jetting to suit the engine and exhaust modifications. I never tried a direct comparison of it against an XR, so it is hard to say what the performance difference was, but the big bore kit would have been the greater power increase.

CJ

[Andrew L]

Thanks for the info  CJ I've started messin with it, it was smoky so I pulled it down for a look gave it a hone and a set of rings friend owns a head reco business so it had a valve grind and new stem seals going back together at the moment might have to find an xr cam while its apart cheers Andrew