Yamaha XT250, thread size/ pitch in rocker shafts.

arcticXS

XS650 Guru
Top Contributor
Messages
1,809
Reaction score
2,606
Points
263
Location
Tromsoe, Norway
I am currently messing with a 80-82 XT 250, and need to pull the rocker shafts. They are drilled and threaded, but not a common thread. M6x1.0 does not fit, M5x0.8 can be pushed in. I suspect M6x0.75, but cannot be sure. It is impossible to check with a thread gauge. Any ideas?
 

arcticXS

XS650 Guru
Top Contributor
Messages
1,809
Reaction score
2,606
Points
263
Location
Tromsoe, Norway
Problem solved. I ran an M6x1.0 tap into the bores, and that must have removed the tiniest amount of sludge or whatever, so now that M6 bolt goes in. I plan on blasting the outside of the head before removing rocker shafts, rocker arms, camshaft, valves&springs. Just thought I'd clean up any casting flaws and do some light re-cutting of the seats before assembling this engine with a new camshaft, timing chain & sprocket, etc.
 
Top