Is around 15 foot pounds the correct torque spec for a US model 1974 dt125a? I have an Australian manual and says a 125 is 2.0 m-kgs or 173 inch pounds or 14.5 foot pounds. Is this about right? Or is that just for the non US models?

US manuals are available here in Tech Library. 

Thanks for the reply but there is no manual for this bike on here. Only at1-2 manuals that don't even show that cylinder head torque spec.

Page 18 [think its page or chapter] & 7D has torque values. yours has the long tube head bolts [4 of] so be same as anything AT1-2-3 etc 13--18 ft lbs Page had 18/189. You'll need to rotate it & expand or its just my computer.

www.yamaha-enduros.com/index.php/service...a-b-c-service-manual

Actually there is more than one US manual that covers your bike in the Tech Library here.

Factory manual: yamaha-enduros.com/index.php/service-man...vice-manual/download   (Page 21 of manual, 32 of PDF)

Intertec (I think?)  yamaha-enduros.com/index.php/service-man...nge-manuial/download  (page 38)

And even a third but it's kind of very generic aftermarket manual and I don't feel like looking through it for torque specs. 





 

 Just gotta be careful manuals aren't talking about the head [whenever it changed] with a ring of 8mm short studs & cylinder held on by long nuts down holes in the fins. Hope i sent the right link, here's a screen shot if i can make it attach.
Need good eyes to read it.

Thanks guys. I have them at 15 ft lbs and it seems fine. Only had to tighten up one a smidge after hours of riding. Has zero air leaks though. Vibrates alot when I'm at a higher rpm but I hope that's pretty normal lol.  Always starts first kick. Very happy with this thing. The shorter yz85 crank collar paired with the later model outside threaded crank shaft has been working nice with the VAPE system.

Umm--i missed the bit where you've been changing crank bits & fitting a Vape system. So disregarding that--my first & only thought on vibration is engine mounts not tight--or not tight enough. But then again is it a Vape ballance thing!!.

Not relevant but had bad vibes [real bad] when roaadracing my RT1 minus the mag cover to let things cool a bit better. & rivets all broke & flywheel passed the opposition going faster than me haha [well almost took out another rider but stopped rolling in the grass just short]. Didn't damage the coils or anything which it sure would've if the cover had been on.