TT500 Pre 78 legal?

[Graeme M]

Now I know I should just read the MoMS but I thought I'd be lazy and just ask here.

I am thinking of building a TT500 to race vintage dirt track next year. I'd like it to be Pre 78 legal so's I can maximise the number of classes I can enter. So clearly C/D models are fine. But does the 78 qualify as a flow on? I assume the 79 doesn't, although what about a 79 XT? Or are all the 500 Yamahas Pre 78 legal? Anyone know?

I know where my 79 TT500F that I sold in 1980 is and wouldn't mind trying to convince the owner to part with it, but maybe a 79 isn't the best option?

Thoughts?

[brent j]

If I remember rightly as long as it has inline forks it's ok, leading axle forks are 78 onwards.
I'm not sure what year the alloy swingarm came out but if it's after 77 it might not be legal.
I'm sure that everything else follows on

Cheers

Brent

[steve234]

I saw a TT at CD7 which had leading axle forks and an alloy swing arm.  The dude said it was pre 78 legal, but I can't remember why, sorry.  It was very very nice and had me thinking the same.

Cheers,
Steve

[LWC82PE]

79 TT definitely wouldnt be a follow on as it has leading axle, but 79 XT still has the non leading axle. If you tell me what year TT or XT you are planning to use/want to use/trying to get through as a follow on, and i will ask a guy i know who is an expert on those bikes and see what he says. He pretty much knows all the little differences on all the 500 yams and will be able to say if there is a significat difference on a newer model that would not allow it for a follow on.

[jimg1au]

from ma web page

Yamaha


TT500, up to 500cc
displacement, with
allowable overbore
1975-78
so if you make you 79 look like a 1978 non leeding axle should be ok

[Graeme M]

I guess for the moment just trying to see what models I can choose from. I'd like to get a 76, 77 or 78 so it's legal, and I'd prefer a TT. The 79 TT is a little different with leading axle fork, box section swingarm, and some minor engine changes (bigger exhaust valve I think from memory).

My plans are modest - clean the engine up, the usual go fast mods like carb, air filter and pipe, hi-comp piston and maybe a cam though stock is OK. Maybe some RM-B forks and a set of YSS shocks, possibly an ally swingarm if I can find one. Then go do some skids.

[JAP 454]

Graeme , as far as my Manuals  tell me , all XTs and TTs from the '78 model on have the 47mm inlet , nearly bullet  proof motor, Ivan Tighe 323 cam great for Dirt track.
Foss

[Graeme M]

Sounds good, Foss. I'm always impressed how quick people can make the old XT/TTs and XLs go!

Mind you, I see they aren't cheap. There's a few XTs on eBay for rather steep money. Especially given most of them are a bit ordinary...

Gotta sell the 05 YZ125 first to finance this plan, so will be a little while yet before I can go looking seriously.

[GMC]

The tanks on the models with leading axle forks are slightly different too, but they are just cosmetic as far as the rules go.
A lot of MX modified TT / XT's have been fitted with leading axle YZ forks so as long as they are D model or earlier they would be okay.

[Graeme M]

That'd be my thinking Geoff. Most 500 Yammies have been modded all over the shop. As long as an XT/TT has the right suspension travel limits, I'd reckon any year model should surely pass muster as a pre 78. If you can build an HL500 with a worked motor and have it accepted into Pre 78, then surely a stock '80 model should qualify as a follow on and therefore slip into Pre 78?

[GMC]

Maybe the Alloy swingarm was available as an option during the earlier years

[Graeme M]

Now you know that swingarm wasn't ally don't you? Would it really have made much difference to the handling of one of these things? I'm doubting it.

Still, I'll do whatever is the right thing to have it Pre 78 legal...

[steve234]

Try one of these swingarms.

RACING SWING ARMS - TT500 / XS650
STRONGER, LIGHTER & "TRICKER"! Custom Refurbished YX600 Swing Arms.
 Extends TT500 Wheelbase. Bolt-On to All STOCK TT / XT / SR / XS Frames without Modification.
 TIG Welded 3 Position Champion-Style Lower Shock Mounts.
COMPLETE with Needle Bearing Pivot Sleeve, Dust Caps, Rear Axle & Adjusters.
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Cheers, Steve

[Graeme M]

That does sound cool... Might have to look into one, huh?

[crash n bern]

The swingarm options would be a DG steel one from the era, don't come up very often but ussually run at around $120us or a Pro Fab alloy one, the pro fab's run at about $350-400us + $70 odd for shipping on ebay.  Cheapest option would be a '77 RM alloy swingarm.

The alloy Yamaha swingarm is the same dimensions as the steel one so it's of no real
benefit.

Pro fab also made triple trees for the TT that decreased the rake.