I have a 1978 xr75 with scored journals on the head, Cam is also spent. Will a 1980 xl80 head and cam interchange onto the '78 engine? Looks visually close but don't want to make a pricey mistake.
Yep. Compression may be slightly lower, and fins bigger, but it's a bolt-on. Cam from the 100 has a MM more lift, too, adding a bit of top end performance.
Can't remember which, but XL heads also have a head stay mount on them that the XR's don't (the 100's do for sure....maybe the 80's dont....code on head is 152). The XL head is a drop in like FP said.....go with a 100 cam or buy aftermarket and add a pipe and carb w/opened up airbox for good performance, if that is what you are looking for.....
Thanks for the replies. I will be tearing down the xl this weekend, fingers crossed that the head is in better shape. If memory serves, that engine jumped time so likely bent valve but hopefully no scoring.
Question on the 100 cam - will a stock cam from a 2004 crf100 fit? I upgraded my 100's for at-home flattracking and have two stock cams sitting around.
The xr75 will be a rider, want it nice but not restoration-quality. I'm also working on a 1975 xr resto project but not finding the parts I need at a reasonable price so it sits... So many projects and so little time.
Terry, I'm the guy who traded you the xr100 engine for the Pitster parts last year - man, that bike is fun!
1975:nicer set of fork legs, decent tank and a new set of rims/spokes. 1978: one non-pitted fork leg, perches and lever covers (used ones) to give it some semblance of oem. Could also use a reasonably servicable stock pipe.
Absolutely! The first version XL's to not use the old-style (SL/CL/CB) 100 engines, I think in 1979-80, maybe 81 as well, had a cast in head stay lug to tie it into the frame....I may be old, but.....err, uhh....what was I gonna say?!
Oh yeah! That I can remember stuff....sometimes, well, alright, occasionally!!
No, What I meant was the 79-85 XL100S Honda head HAS A HEAD STAY.....and, bolts on later XR/CRF100/80 cylinders.......check the fiche....you, you, you,....non-believer!!! lol