Brand New SR400 Vintage Flattrack Legal?

[SON]

Brains trust
I think they should be aged as if they are a SR500 follow on,

[allan hughes]

what is a sr400

[Mick D]

AS A FLAT TRACKER




REVIEW SR400
http://www.cycleworld.com/2014/03/06/2015-yamaha-sr400-first-look-review-photos-specifications-pricing/

[SON]

I will begin to stock body work both Flattrack & Classic

[pancho]

They are a great looking motor, I was speaking to a bloke from Dues at the Eastern Creek 'Bogans Day Out about these things and in particular about the way the motor has been through bolted. What got my interest most was that even though they are manufactured as a 400cc unit the can be enlarged to 500cc and even to 550!.
If the head can be opened up for adequate breathing well there you go! How would one of those donks go in Peter Cambells frame I saw on here a while back!!
  Get a few of them to come out on club days and see what happens next!
 cheers pancho.

[SON]

Or 605cc
Powroll short rod Stroker
Beautiful work

[matcho mick]

so, nobody remembers hypertech,750cc  ,

[Michael Moore]

pancho, the SR400 is a destroked/long-rod 500.  The cylinder height/bore is the same, so swap in a 500 crank and it is a 500.

I suspect they will be popular in dirt track and vintage RR with big bore pistons to make short-stroke near-500s.  The 500 rod ratio is pretty short and they respond well to a longer rod, but that means spacing up the cylinder, lengthening the cam chain and squeezing it back in the frame.  A friend built a couple of 500s by welding and reboring the pin holes , long Carrillo rod + big bore.  I think they might have been 92x75 but it was a long time ago and I don't remember for sure.

Starting with a 400 crank will make things much easier.  Plus it should improve engine parts supply through Yamaha dealers for the old XT/TT/SRs as I don't think Yamaha has changed much.

cheers,
Michael

[SON]

Fuel injection but covers etc look the same,
My 605 was built on brand new cases, covers etc saved from the early 80's
Now 30 years later they are more readily available
Anyway good on Yamaha Motor Australia for bringing the model in,
I am looking forward to listening to more Thumpers on the road
And hopefully the track.

[GMC]

I wonder how the fuel injection would cope with the increase to 500cc or more
Did Yamaha allow the system to be programed for different tuning scenarios

I don't know about using the fuel injection as far as vintage events are concerned?

[steve234]

How about a stock engine modified everything else class for dirt track. e.g. Knight frame, down pipe, R6 forks, 19" wheels front and back, wide bars blah blah blah.

[steve234]

[firko]

I'll play good cop/bad cop on this one. If we allowed the SR400 in as a flow on would it open a hornets nest of "What About Me" claims for other bikes to be considered? It could turn a simple situation into a litigious legal nightmare. The good cop side of my personality (incidentally, the stronger one) says that if it's indeed a legitimate flow on from the XT/TT/SR500, why not? Dues ex Machina has made a living modifying grey Japanese import SR400's for years, as have a number of foreign and Japanese firms. They're the street tracker/café racer/bobber flavour of the moment. My only reservations (bad cop again) are whether the frame is identical or reasonably close to the legitimate SR500 version....if it is, knock yourselves out building them into trackers. If the frame is different enough to be excluded as a proper flow on I'd still allow the engine when fitted to a legal aftermarket or production frame. I'd assume the idea would be to allow the bike into pre 78 or Evo or have I got that wrong?

[steve234]

Sorry folks, I got carried away again. Back to the original thread.

[SON]

My plan that it be accepted into "Old School" Singles
Fuel Injected or Carbed doesn't matter,
The more the merrier,
400/500/540/560/605cc who cares ?