How much of the WR/YZ frame is oil rez?

Is the rectangular, vertical downtube the only portion that holds oil? The new guy on the YZ forum, "lightestYZF with the 215 lb chromoly frame", (and the stinkin' Iowa DOT), have me thinking seriously about custom frames...

Since Iowa, and most states, would license a homebuilt/custom aftermarket FRAMED bike with no hassle (just like "Harleys" from a frame kit) as "Specially Constructed". Iowa Law DEFINES and identifies the origin of a motorcycle strictly and unreasonably by its frame, as opposed to the body on a car or truck, making it very difficult to escape Yamaha's frame number/MSO restrictions. Most states are similar. This is how more and more states are killing our D.S. 'conversions'. Too bad somebody can't crank out aftermarket frames for our bikes like they do for Harleys. A universal '98-'03 frame that would accomodate all the engines/suspension components.

My battle hinges on the "Reconstructed" title they issued my bike. I will beat them at their own game. And that's all it is. When you have too many pencil pushers eating at the public trough, and too many tax dollars to waste, this is what you get! :)

We are talking 426 and not 450 right?

Is the rectangular, vertical downtube the only portion that holds oil?

Sort of. I believe the threaded tank mount in the frame passes through the reservoir, so I guess you could say a portion of the tank is in the downtube/backbone part.

Of course you are not committed to that location. The oil res can be anywhere, having lines made would not be a huge hurdle relative to making a frame (!). It could probably also be smaller, like the 450. Almost 2 quarts of oil in a 436 cc motor is probably a bit of overkill.

That's a real good point, Hick. This has me very intrigued. I will soon have a bare frame to do some serious what-iffin with...

Do you think there would be a big demand for an aftermarket frame?

Obvious points would be it would be alloy, to save some weight, it would have the universal minting points for everything from different models, it would have some options as far as sizes go (Wu could get a smaller seat height one by having an adjustable backbone and changing the subframe)...

what else would you change in the existing frame?

Two swingarm positions one giving a longer wheel base...?

I think the rake on the forks is something you may be able to tweak, a bit steeper for faster turning, or more shallow for the desert riders...

What about peg mounting points... adjustable for up/down and front/back...?

You could have a remote reservoir for the oil, in a finned canister, to aid in cooling...

Don't make me fire up the TIG welder just to prove these things... :)

Will that be polished alloy or powdercoated in a choice of colours...? :D


Those are some great ideas! Why have just an oil reservoir when it could be a finned aluminum unit for extra cooling?! Thought about that one myself as I drove all night, David. Great minds and all... I love the adjustable seat height idea. KTM 50cc bikes were built that way. The whole tank/seat/fender assembly adjusts very simply. Not only up and down, but fore and aft.

And the foot pegs... That was one of the first mods I did to mine.

As a practical matter, these bikes and their base components have proven themselves and will be around for a long time. With increasing EPA regs, they may become ever more desirable. There are inumerable aftermarket parts available. A great deal of the parts interchange. More and more parts are available all the time, both new and used. Several people on this forum have pieced their own bikes together.

From both a performance and a "street-legal in all states" perspective, I think there would be a market for such a frame. It would absolutely solve my problem in Iowa. Specially Constructed or Homebuilt vehicles are allowed in even the most restrictive states and are not subject to near as many restrictions as production models. Case in point: Jesse James and his bikes. Street legal artwork. Way out there!

Like that new monster ATK 2-stroke in a recent post: Build the bike with proven top-shelf stuff in the first place. We currently spend small fortunes upgrading everything anyway. With a custom kit-frame and a motor and suspension and brake system (the best parts of these bikes), the rest is pick and choose.

The factory frame is well made. I know of no failures. I would like to know what steel alloy is used. It could well offer room for lightening, as it is probably overbuilt to compensate for a lesser grade of steel. 4130 moly may be both lighter and stronger.

For me, the welding is no big problem. My buddy could handle the machining. I have an excellent steel supplier/advisor (knows his alloys!). He also has a high-tech water cutter that cuts anything with nearly laser precision. The precision bending is the weak spot off hand, but definitely solveable. Obviously the first one is by far the hardest. Once the jigs are made...

Maybe we could collaborate the project to skilled and interested TT members; each providing a specific area of expertise or top-shelf component. The ULTIMATE PRIVATEER THUMPER!! <220 lbs(with e-start?), 500cc, street legal... :)

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