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kshansen 01-10-2013 02:18 PM

Sub Frame for an XS400?
This is probably a bit out in left field but has anyone built a subframe to mount a sidecar on an XS400 Yamaha?

I have an old 1978 XS400 sitting here and an old Velorex Sidecar sitting in the barn and for some reason I was thinking hooking them together could be a fun project. Not that I don't have enough projects already!

One thing that adds a little challenge to this is this is a kick start only bike, so have to keep clearance for that in mind. Another thing is the frame has only a single down tube in the front. Center stand is already off so that is the one good point to start. One other thing I have to watch is the oil filter is right on the front of the engine so need to keep access to that. There are two 8mm bolts for front motor mounts on either side of filter that might be usable.

Might try some P.A.D. work, a cousin to the C.A.D. work some are familiar with.

Not thinking this will be an outfit for high speed Interstate runs just putting around local roads.

C.A.D.-Cardboard Added Design
P.A.D.-Plywood Added Design

Leaf 01-10-2013 07:00 PM

That pairing makes me drool. :3

I wanted to build my outfit with a mid-range XS (I was looking for a 650, but I'd have taken a 400 too), but the CB400T was what turned up in the beer-money basket-case range.

It appears to me that the XS400 has a full-cradle frame and the exhaust is high enough to not interfere with the lower mounts, so I have a sneaking suspicion that the Velorex U-clamps could probably be used at all 4 points. Though I'd probably put a little weld or strong epoxy on the lower ones after getting everything lined up, to keep them from twisting.

My biggest worry would be the rear lower mount getting in the way of the kicker, though, unless it was scooted forward a little too much.

I personally don't think the Velorex is heavy enough to really need a subframe for strength. I have one of my lower mounts bolted into a crappy pot-metal bracket that holds the footpeg and exhaust, and it's been just fine, even with all three wheels off the ground a time or three and some not entirely nontrivial off-roading. :3

Edit: Make sure to post a build thread. ;3

MILLENNIUM FALCON 01-10-2013 07:04 PM

well there isnt much xs400 left on my bike....other than the engine, maybe my build will help you a little bit. my bike was an 81 xs400 when i started messing with it. my sidecar is almost finished. good luck on your build i hope to see some pictures once you make some progress. it will be cool to see another xs400 with a chair! good luck. here is the link.

zipper421 01-11-2013 03:45 AM

where are you located
im in syracuse

jaydmc 01-11-2013 07:56 AM

This would be a sweet match up once done, I had a factory built MZ silverstar gespanne for a while, These are 500cc sinlges with a factory installed Velorex sidecar. It was a blast. I have never done a bike like yours however I would start by making a sub frame, perhaps mounting to the center stand mounts that allows you to move the rear lower mount much further back in order to allow for the kick starter to work.
Jay G
DMC sidecars

kshansen 01-11-2013 03:35 PM


Originally Posted by zipper421 (Post 20453168)
where are you located
im in syracuse

I'm just down the road in Elbridge.

Do you know a good place to by steel tubing in Syracuse where they don't want to sell you 20 feet? Thinking if I ever get started on this build I'd like to use maybe 1 1/4 square tubing. But would be open to other ideas. Seems square or rectangle would be easier to make joints.

Leaf 01-11-2013 04:18 PM

Maybe try a scrapyard, if you don't mind taking care of a little rust. I don't know if they'll sell scrap rather than just buying it, but I say this because I get my metal bits from the scrap pile down on the farm, which we sell to a scrapper when it gets too big.

Plumbing companies and the like (the ones that deal with commercial/industrial construction, not home repair stuff) might sell/give you castoff pipe, too. When I worked for the electric company, we often threw out many 3-5' lengths of perfectly good EMT conduit at the end of a job, so I assume the same would be true of construction outfits that deal with thicker, more structurally sound piping of various sorts.

zipper421 01-11-2013 07:17 PM

i buy lot of steel from klein on gm circle its all drops and leftovers and you can buy it buy weight
lots of good stuff
klein steel direct 315 454 3165
ask for howard

kshansen 01-15-2013 12:43 PM


Originally Posted by zipper421 (Post 20460790)
i buy lot of steel from klein on gm circle its all drops and leftovers and you can buy it buy weight
lots of good stuff
klein steel direct 315 454 3165
ask for howard

Well I picked up my new sub-frame today. Or at least the start of it!

35 lbs. of assorted steel for a total of $21.60. Now the fun begins.

Unfortunately have to be out of town for at least two days, then have Friday with two different doc. appointments.

Zipper, thanks for the heads up on Klein Steel, I was like a kid in a candy store. Howard is a great guy, he knew who sent me when I mentioned another guy building a sidecar sent me. Klein has branches all across New York so if anyone is near one of the major cities and needs some materials I would suggest checking them out.

zipper421 01-15-2013 02:12 PM

glad you made out good
i was just pulling in when you left
howard said you were pulling down the ramp we were pulling in

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