mx 400 B ?

[motormouse]

Looking at what looks like a MX 400 B which the guy is telling me is a rare, limited run of 500cc prototypes made by yamaha. Engine number 574-000323, frame number 509-007392 and 5000 cast in bottom left of barrel.
   Has anyone heard of anything like this or is he full of it. Any info would be much appreciated.
     Thanks Dave.

[brent j]

So far it looks like an MX250 frame with a DT400 motor

[Iain Cameron]

Can't find a 574 xxxxxxx could it be 57H . according to my knowledge there was no such bike the # 509 is the prefix for the 75 mx250 b . after the sc500 ,the 490's from 82 on were the closest to 500 2strokes made . Iain

[Iain Cameron]

bitsa unless its cheep keep away Iain

[motormouse]

Thanks for the info guys, he tells a good story. I think he may have forgotten to take his medication this morning!
       Thanks Dave.

[brent j]

I seem to remember this same combination being advertised once before, and as a 400B then too.

[tony27]

I thought someone bought the thing before finding out it was a bitsa

[motormouse]

A google search turned up the very same bike. 



             http://www.vintagemx.net/blog/1975-yamaha-mx-500-prototype/

[Slakewell]

The MX 400B is half a thing IMO

[IT400C]

Can't find a 574 xxxxxxx could it be 57H . according to my knowledge there was no such bike the # 509 is the prefix for the 75 mx250 b . after the sc500 ,the 490's from 82 on were the closest to 500 2strokes made . Iain

509-007392 would be one of the last 1975 MX250B's manufactured...........
574-000323 would be one of the earlier Australasian 1976 DT400C's...........   

[Iain Cameron]

Well one learns something new each day IT400C , I didnt think of the DT . Iain