YZ D eligibility

[GMC]

I have a customer with a YZ D model thats been fitted with a E model swingarm.
Is this legal for Pre 78?
The Suzuki boys claim the 78 arm was available as an option in 77 so I was wondering if this was also the case with the Yamaha?

I have told him I don't think it would be legal but I thought I should check before he buys another arm.

How toey do Viper get on things like this?

[bigk]

99% won't care in the slightest and would welcome another bike on the track, but it only takes one and theres usually one in every bunch.  If indeed it was available as an option in '77, there ain't no problem. Fit the swing arm, go racing, have some fun and deal with the protest when & if it comes. I doubt it will come unless your mate in is the points race  for a 1, 2 or3.
Cheers,
K

[E74]

Other option is an aftermarket aluminium swing arm from back in the day, getting scarce nowadays but..

[GMC]

He bought the bike recently & it had the alloy arm in it.
I don't think he wants to spend the money on something else.
I have seen aftermarket arms for the YZ's & they do seem to be scarce.

[holeshot buddy]

like K said technically it is illegal
to have an e model swingarm
dimensions are identical to the d model
its just alloy
club days fine, national or state titles
you could run but if you are in the points
someone could protest and you would be stuffed
which is silly really its not going to make you any faster
with it on
depends how serious you want to race

[squirtmoto]

Yeh Russ is spot-on!
I have a 400D, it had an alloy swing arm but I have changed it back to STL.  The dimensions are identical to the alloy, which would be allowed under the clause "if it remains unaltered from standard" the only difference is the weight. I weigh 104kg's so I guess everyone else should carry a weight handicap

Bill.

[mboddy]

A YZ400D with a YZ400E alloy arm is a YZ400E. He can race it in EVO and Pre-85.
I have seen where this sort of thing can go if not stopped early with Historic Road Racing Period 5.
It ends in tears.
The best approach the scrutineer can do is to give a warning the first time at a club race meeting.
If it is not sorted out the second club meeting then it must be knocked back.
 

[Nathan S]

"Nah, its not a production E swing arm, its a replica of the works part from 1976. Really rare part, they only made them in 1978".

Yes it would make me a rule-bending c%^t, but if it went to the judicary, I wouldn't lose.