´74 MX 400?

[Iain Cameron]

In 75 there where no large YZ 's made , the 250 and 400 MXb's where to replace the mxa's they share the first 3 digits on the eng and frame # 509-0 for the 250 and 510-0 for the 400 , the main difference is square upper rail on the swing arm and forks 35mm for the MXb and larger with the 1976 only Air canisters for the springless forks . The YZc 250 and 400 eng and frame #'s are 509-1 and the 400 is 510-1 . Iain
now were is my Anorak .

[Ktm181]

In 75 there where no large YZ 's made , the 250 and 400 MXb's where to replace the mxa's they share the first 3 digits on the eng and frame # 509-0 for the 250 and 510-0 for the 400 , the main difference is square upper rail on the swing arm and forks 35mm for the MXb and larger with the 1976 only Air canisters for the springless forks . The YZc 250 and 400 eng and frame #'s are 509-1 and the 400 is 510-1 . Iain
now were is my Anorak .

Thanks for the replies guys,

so how much difference performance wise is there between YZB, MXB AND YZC??  Yzc and Mxb I am assuming are very similar??? 

thanks for the advice,
Kt.

[Rossvickicampbell]

and Mr Iain - when did the MX's stop?  I reckon would be a great reliable bike for pre 78 - have always liked them.

[Iain Cameron]

!975 was the last year for the larger mx bikes there was a 125 in 76 (quite a collectors item ) the 100 dt was called a mx into the 80s and in the UK the 175 was called a mx but it had lights . KTM181 the YZb was the last of the short motors (same cases as the DT1\RT1 ) the MXb's were the evolution from the long motor used in the 73 mx 250 and 360 . The YZb like the YZa where a light weight motor meaning that any part that could be drilled or made hollow was , Gears where drilled , the shafts for the gears had holes drilled down  the ctr , clutches looked like swiss cheese ,even the selector drum was drilled . The YZa and YZb were a true works copy in my opinion and small production numbers . Where as the MXb  and YZc  were sold as large number production motocrossers  the 400's had a solid motor and as reliable as a house brick ,  it had a very good spead of power almost tractorish  compared to the YZb it was a low reving motor with a very wide power band . The YZc 400 was much the same , porting was changed and I think the gears were changed slightly . Rosco they are both good bikes for pre 78 but a little short on the suspension side and heavy porkers (I campaigned a YZc400 for years ) . Iain

[Iain Cameron]

Just a side note I have read that Yamaha intended to drop the YZ from the public range in 75 -76 to keep the mx as a clubmans bike and the YZ as a works limited copy only sold to guns . Iain

[Ktm181]

!975 was the last year for the larger mx bikes there was a 125 in 76 (quite a collectors item ) the 100 dt was called a mx into the 80s and in the UK the 175 was called a mx but it had lights . KTM181 the YZb was the last of the short motors (same cases as the DT1\RT1 ) the MXb's were the evolution from the long motor used in the 73 mx 250 and 360 . The YZb like the YZa where a light weight motor meaning that any part that could be drilled or made hollow was , Gears where drilled , the shafts for the gears had holes drilled down  the ctr , clutches looked like swiss cheese ,even the selector drum was drilled . The YZa and YZb were a true works copy in my opinion and small production numbers . Where as the MXb  and YZc  were sold as large number production motocrossers  the 400's had a solid motor and as reliable as a house brick ,  it had a very good spead of power almost tractorish  compared to the YZb it was a low reving motor with a very wide power band . The YZc 400 was much the same , porting was changed and I think the gears were changed slightly . Rosco they are both good bikes for pre 78 but a little short on the suspension side and heavy porkers (I campaigned a YZc400 for years ) . Iain

Thanks for the reply Iain,

mate superb info.  I REALLY lusted over those "cantilevers" when I was a 15 year old, hell, my mates and I even had a teacher at school nick named Miss Cantilever, some weird interpretation of how a 15 year old thought a bra worked!!!  Have longed for one ever since, a bike with cantilever rear that is, much more interesting t,han bras!  I especially like the mx400 and 400c, I stupidly passed up a very good 400c some time back, its still on my bucket list of bikes though.....

cheers,
Kt.

[Iain Cameron]

My 76 models at the moment the 250 is spread over the shed floor .  Iain