Model-Year Differences: Exhaust Mount/Bottom Motor Mount

[OakBehringer]

Are the bottom motor mounts in the same position on a '73 TX650 as they are in later years? I would assume so, but when I hold up some unknown year head pipes next to the bike, it looks like the tab on the pipe will be about an inch too far back on the frame. This is assuming that the tab gets bolted to that bottom motor mount...

Thanks!
- Adam

 

[5twins]

I don't think the '70-'73 headpipes bolted to the frame. Instead, that tab on the pipe was connected to the round clamp on the muffler using a short plate .....

I don't think the motor mount locations ever changed. Later frames did have muffler/headpipe mounts incorporated onto them (separate from the motor mount). Go here for exploded parts diagrams of every Yamaha bike model back to '63 (that's where these pics came from) .....

http://www.yamaha-motor.com/sport/parts/home.aspx

 

[OakBehringer]

ah ok - that makes sense - I'll have to re-think this.

Thanks!

 

[XSLeo]

On the 70-73 the lower engine mount bolt went thru the frame, in 74 when they redesigned the frame the bolt went thru a mount on top of the frame.
On my 75, the same as the 74, there is a tab on the frame behind the lower engine bolt, it has two threaded holes. The headpipe has a tab that bolts to the front hole. The rear hole is for a p-clamp that goes around the nut that holds the muffler to the headpipe. Parts #7 and #14. In 5twins pic.
I think you can use the unknown headpipe by building brackets to fit as in 5twins pic.
On the later Specials the exhaust being welded together only has a tab that bolts to the front hole of the tab on the frame.
I haven't tried it but I think the tab on the frame will let you use any of the standard headpipes on any year frame.
The way the muffler hangers attach to the frames are different between the standards and Specials. So bit of bracket making will be needed there.