Yamaha TRX850 Enthusiasts Forum

I've been rebuIlding an 850TRX cylinder head for a friend, all the exhaust studs were sheared off at the head, they're also pretty mangled and it's difficult to get there exact size. so can anyone help me out, I've got the machinery to drill and tap new holes but Yamaha have proved useless in giving me the info I need.

What is the diameter of the stud. M8, M10 etc.?

What is the thread pitch?

What depth does the stud sit in the head?

Obviously I'm trying to recover the original thread, but I need this info.

Any help appreciated.

Kind Regards,

Jacques Wood

M8 x 1.25 pitch, length is pretty much up to what you need really. I will have to replace mine once I angle grind off the alloy collars from the stock front pipes.
Ferkin ridiculous of Yamaha to have snugly fitting alloy collars over steel studs, but hey it`s not Just Yamaha that do it, alloys and steel in close contact, add road grime and salt, you`re going to get a problem!
See this thread by the way:

http://trx850.motomaniac.net/forum/view ... aust+studs

I too will be using the split Kawasaki type collars, AND brass nuts on the SS studs I intend to fit. All exhaust nuts should be brass, it remains `undoable` throughout it`s life.
Edit:

Just noticed that was your first post, so hello and welcome from me too.