gurt

Member
Feb 25, 2006
111
0
I recently picked up an old yamaha from the mid ohio swap meet that I hope to have ready for the motocross next year. the problem is, I am having a really hard time figuring out exactly what it is. I was told that it was a 1976 but other than that the guy I bought it from had no idea. It has white plastics and tank, the tank says 125 but the cylinder is marked as 171cc, it has an odometer or speedo pickup on the front hub, twin shocks, it's not oil injected, the carb is a 34mm mikuni, the head has 2 spark plug holes, the frame and engine number is 565000445, and upon pulling the flywheel it has points and a lighting coil. I have looked around for a while online and can't figure it out. Any help would really be appreciated.
 

DougRoost

~SPONSOR~
May 3, 2001
720
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The twin spark plugs makes me think it's not a DT...did the MX's have that type of head?
 

BadgerMan

Mi. Trail Riders
Jan 1, 2001
2,479
10
1976 MX125C

Cool bike!
 

gurt

Member
Feb 25, 2006
111
0
Were the 175 cylinders interchangeable with the 125 bottom ends? The way the pipe fits and the good compression just seem to be too good to be true to me if thats not the original top end.


-thanks everyone for the help so far :nod:
 

Rotorranch

Member
Feb 10, 2007
436
0
Don't think it's an IT175 top end...the IT175 engine sitting in my garage has a RADIAL FINNED head.

Both of my 175's ( DT175, CT-2 or 3? ) have a dual plug head.

It doesn't look to me like a DT frame...the shock mount doesn't look like the right position.

I think it's indeed a 125 MX, with a 175 top end. :nod:

Maybe a Yammie dealer could tell for sure from the serial numbers?

Rotor
 

BadgerMan

Mi. Trail Riders
Jan 1, 2001
2,479
10
It's a 1976 MX125. It appears that some one has put a DT175 top end on it. As said above, it is not an IT175 top end as they had a different fin pattern.

The 1976 MX 125 was the only MX model they offered that year along with the monoshock YZ's. It was a one year model that was different from its predecessor (the '75 MX125) which had straight up thermal flow shocks and a different shaped tank (although the colors were the same).

A friend had one and I remember it being a real nice bike.
 

mbaird

Member
May 25, 2006
66
0
I had a '75 mx250 back in 77-78 and it had a monoshock
suspension, radial finned head and the white color scheme
just like this one.
I was sure it was a '75 but have never seen another with the radial fin head or monoshock.

anyone know??? am I wrong about the year??
 

DougRoost

~SPONSOR~
May 3, 2001
720
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I remember the monoshocks coming out in the '76 model year as a major debut. This probably was calendar year 1975.
 

gurt

Member
Feb 25, 2006
111
0
Ok, so one last question. Does anyone know where I can find a performance pipe for it?

-again, thanks to everyone for the help.
 

dirt bike dave

Sponsoring Member
May 3, 2000
5,349
3
FWIW, not every company's website is 100% inclusive of all their products. It does not hurt to give them a call and find out if they have something that will work sitting on a shelf.
 

Enduro_Nut

~SPONSOR~
Feb 7, 2002
1,155
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If time is no problem Circle F might make one for you. As mentioned, call Rick @ Vintage Iron and talk to hime about it, he may have a solution for you -
 
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