Trick 1973 Yamaha 360 MX

[firko]

So how does that fit into pre 75 if you make a swing arm or use one of them bs ones etc and the shock mounts are obviously in a position differant to standard as per the rules ?  how does that work ? or can i take a standard MX swing arm and add Another 1 " after the shock mount as done in the day and still be legal ?  the swing arm Rules are very Grey i think .

There's nothing obscure about the rules. As long as you use the standard top and bottom shock mounts and maintain the same geometry all is well. Any swingarm lengthening should be behind the shock mount to maintain the same shock/swingarm/frame triangulation. One side issue that does arise from lengthening the swingarm behind the shock mount is that it slightly increases the rear suspension travel so it pays to keep an eye on that department.

[Marc.com]

And losing that cravass between the tank and seat marc would help....

# So how does that fit into pre 75 if you make a swing arm or use one of them bs ones etc

# the bike at the top while being a tidy unit, really hasnt had a lot done to it, visually it still looks like a plain jane MX with a small tank and a differant arm, for what they probally spent on it id like to see somthing a bit better visually than that in the garage......

How does a FOX swingarm fit into the era being 2" longer, or should we just keep everything stock like in the old days

I mean MX has a history which included a few hop up parts, building a better mousetrap was part of the deal. The rules allow for that.

The cravass between the tank and seat is due to lack of automotive upholsterers in Shibuya. Much harder to build these bikes in Japan, you just use what you can find.

[TM BILL]

Novation = bad Period PDI = Good


[/quote]

Mark with a little work you could make that look really nice lose the kids shop project swinging arm and the undersize tank , fit some shorter shocks and you could build this  Im not sure but i think the Japs even managed to build it in Japan  Oh the cow catcher underneath would have to go to

[Marc.com]

Each to there own Bill, my MX250 has the original tank and I could leave it stink bug stock with ass on the ground rear shocks and trail bike tank, but thought it was boring as regular pussy .

Too much DT for me, then I thought, what if I use the period accessories of the day including the magnificent works PDI swingarm and rare NOS cow catcher, then chucked in a small YZ tank like on the TMGP..... looking less like 'oh no' and more like OW.

[DJRacing]

Each to there own Bill, my MX250 has the original tank and I could leave it stink bug stock with ass on the ground rear shocks and trail bike tank, but thought it was boring as regular pussy .

Too much DT for me, then I thought, what if I use the period accessories of the day including the magnificent works PDI swingarm and rare NOS cow catcher, then chucked in a small YZ tank like on the TMGP..... looking less like 'oh no' and more like OW.

I havent seen an  "OW" looking like an  "OH NO"  before, ......until now.
At least try to get the little YZ125A tank to sit properly and as for the ass on the ground I believe its a better look than a swingarm thats has 5mm angle iron spot welded to it.
I do hear love is blind though.

[Marc.com]

I believe its a better look than a swingarm thats has 5mm angle iron spot welded to it.
I do hear love is blind though.
[/quote]

Yep I love that swingarm , that longditudinal adjustment means I can get her down in the weeds like an MX250 if I feel like low riding.

[Davey Crocket]

Marc, OW and your bike are words and images that should not be mixed together!!!!!!!, and as for calling your swing arm "works"...... you need to wash your mouth out with some saki or are you already on the grog and it's effecting your judgement?......severely. You better hope that Mr Yamaha's henchmen dont turn up on your doorstep and kick the shit out of you for blasfurming one of their products!!!. I think you should be limited to Yamaha piano's or drumsets, just stay away from the bikes.

[Marc.com]

I think you should be limited to Yamaha piano's or drumsets, just stay away from the bikes.

I think this is the bike that Yamaha really wanted to build, but PDI had already developed the swingarm so Yamaha were stuck with mediocre handling made even worse when the monoshock came along.

BTW Bill those shocks look like they were ripped off a Mudbug.

[JC]

How long's the wheelbase Marc? Must be near 59"

[Marc.com]

Yeah its about an inch longer than stock, there are longer arms available in Japan but I think that is over compensating. 

[firko]

I reckon you blokes are a bit tough on Marc and his MX250. While I don't particularly like the YZ125 tank on the MX..it looks a tad too short to my eye I love the fact that he's doing something different and not following the cookie cutter mentality that many seem to follow. As far as the swingarm goes, all it needs is a bit of grinding to remove those fluck ugly gussets and a bit of a sandblast and you'll have a thing of beauty like the one on my Maico (below). Those old Boyd and Stellings/PDI swingarms have a real place in MX history as the first commercially available alloy swingarm having been around since 1969 (documented to quieten a certain WA serial whinger). The period Works shocks are an inch or so too long I reckon, which will really fluck with the straight line stability. Those Works shocks can easily be shortened or if you get desperate I can swap you for shorter 13" versions. I did a similar job on a TM250, turning one of MXs blandest bikes into something a bit interesting, just as you're doing.
Compare my beautiful swingarm to the fugly one on Marcs MX. Hard to believe that they're the same thing.
                             
Boyd and Stellings brochure dated July 1969
                             

[mx250]

                             

(Black rims)

[Marc.com]

thanks for the kind works Firko, the beauty of one of these swingarms is like a good vintage wine and an acquired taste.

BTW if I took the grinder to my swingarm then i wouldn't have the trick 3 position adjustability. Just for a hoot I must take a picture of it in the closest hole to the pivot.

[paul]

what is the swing arm in the last pic

[Marc.com]

what is the swing arm in the last pic

It is PDI RM125, very rare and asthetically pleasing.