Kevin Werner

Amatuer
Top Contributor
XS650.com Supporter
Messages
3,156
Reaction score
13,156
Points
513
Location
Sheboygan, WI
That is a real interesting pic that raises alot of questions for me. When was "monoshock" introduced? I thought 77ish. That raises "Is this Kenny" ? Who I thought was in Europe at that time. If this is a "Factory" bike, why the underperforming front brake mastercylinder? Did those bulges in the headers do something for the powerband? Are those really the lightest wheels they could find for a racing application?
 

46th Georgia

XS650 Junkie
Top Contributor
Messages
965
Reaction score
3,342
Points
243
Location
The Okefenokee Swamp
That is a real interesting pic that raises alot of questions for me. When was "monoshock" introduced? I thought 77ish. That raises "Is this Kenny" ? Who I thought was in Europe at that time. If this is a "Factory" bike, why the underperforming front brake mastercylinder? Did those bulges in the headers do something for the powerband? Are those really the lightest wheels they could find for a racing application?
I've never noticed a front brake on a flat tracker before. I think Yamaha introduced mnoshocks on the MX bikes around '74, and unless those wheels are magnesium, I don't see how they can be lighter than spokes with aluminum rims.
 

jpdevol

XS650 Guru
Top Contributor
XS650.com Supporter
Messages
1,853
Reaction score
4,284
Points
263
Location
26187
I've never noticed a front brake on a flat tracker before. I think Yamaha introduced mnoshocks on the MX bikes around '74, and unless those wheels are magnesium, I don't see how they can be lighter than spokes with aluminum rims.
Yep, factory racer '74 - available publicly '75 model
1974 Works YZ250.jpeg
 

Kevin Werner

Amatuer
Top Contributor
XS650.com Supporter
Messages
3,156
Reaction score
13,156
Points
513
Location
Sheboygan, WI
I've never noticed a front brake on a flat tracker before. I think Yamaha introduced mnoshocks on the MX bikes around '74, and unless those wheels are magnesium, I don't see how they can be lighter than spokes with aluminum rims.
There was more than ovals and road courses in the AMA Championship in those days. There was also a track with a jump and more corners on the dirt I think.
 

Bob Wegman

XS650 Member
Messages
24
Reaction score
71
Points
13
Location
Rochester, New York
The bulge in the exhaust was an attempt to manage exhaust noise without restricting flow, if I remember correctly. Also not sure if the picture is from Ascot TT race. Yamaha experimented with twin shocks and mono shock frames one year. The rider would choose which they preferred depending on the track.
There were 5 racing disciplines in the championship series; short track, half mile, mile, road race and TT.
 
Last edited:

Kevin Werner

Amatuer
Top Contributor
XS650.com Supporter
Messages
3,156
Reaction score
13,156
Points
513
Location
Sheboygan, WI
The bulge in the exhaust was an attempt to manage exhaust noise without restricting flow, if I remember correctly. Also not sure if the picture is from Ascot TT race. Yamaha experimented with twin shocks and mono shock frames one year. The rider would choose which they preferred depending on the track.
There were 5 racing disciplines in the championship series; short track, half mile, mile, road race and TT.
Thanks @Bob Wegman . I had lumped all dirt ovals into one discipline. In those days I was a mere lad and the scant exposure we had was Wild World of Sports.
 

Cheeto775

XS650 Member
XS650.com Supporter
Messages
12
Reaction score
39
Points
13
Location
Pahrump, NV
I've never noticed a front brake on a flat tracker before. I think Yamaha introduced mnoshocks on the MX bikes around '74, and unless those wheels are magnesium, I don't see how they can be lighter than spokes with aluminum rims.
You are close to correct...Yamaha didn't offer the mono shock on dealer bikes until 75 model year...I bought a used 1975 MX250 (400 bucks) back in 77 and it was the most reliable and fun dirt bike I have ever owned...even with the drum brakes
 

46th Georgia

XS650 Junkie
Top Contributor
Messages
965
Reaction score
3,342
Points
243
Location
The Okefenokee Swamp
You are close to correct...Yamaha didn't offer the mono shock on dealer bikes until 75 model year...I bought a used 1975 MX250 (400 bucks) back in 77 and it was the most reliable and fun dirt bike I have ever owned...even with the drum brakes
A friend of mine had an early 360 (75ish) MX monoshock. Easiest dirt bike I ever rode (not that I was any good). It was one of the few that was predictable. Some of the others I rode scared the crap out of me.
 

fred nurk

XS650 Enthusiast
Messages
59
Reaction score
76
Points
18
Location
harrington australia
Gary just take a few pictures of your bike and save them (import them) to a file from your phone
I import them to my pictures file
Then go just below your comment to reply
You will see the icon that says attach files and click on that
It should open up the file with your pictures click on a photo and then at the lower right hand side of the folder click enter and your photo should load onto this webpage
Others will be able to give you screen shots on how it's done
That I have no idea how to do that
Good luck
cheers mikey. the bike sold in 2 days. so ile have to build another one . got a 73 model here so i might build a chopper. the engine needs a rebuild so i might even rephase it while im at it put 700 cc hoos racing pistons in it.
 

Mikey

got muscles in his head that ain't never been used
Top Contributor
XS650.com Supporter
Messages
2,396
Reaction score
7,127
Points
513
Location
Waite Park MN.
Wow that went fast
Good luck on your next project it sounds ambitious
 
Top