Swingarm swap options!?

[cafenewb]

Hey all,

This is my first thread on this site. I've browsed around a lot and have been able to find a shit ton of useful info from build threads, the tech section, etc. I bought a 1982 xs400 maxim awhile back and have been in the process of stripping it down and building it back up into more of a tracker/brat style bike. I'm at a crossroads where I need to decide whether or not to rock this monoshock or ditch it for a dual shock design. The monoshock is in the most inconvenient spot when it comes to hiding the battery and wiring - I can't hang anything from my seat pan, so it has to all be down below the carbs.

I bought a swingarm for a 1981 xs400 special and it turns out to be too narrow at the pivot point, however, the big thru bolt that attaches the swingarm on is the same length. So, i'm wondering if there are spacers or anything that can be used so I can use this other swing arm and rock dual shocks.

This is the stock swingarm

That is like the one I bought off ebay.

And, here is a picture of where i'm at on the motorcycle.

So, here are my options, as I see it.
A) rock the monoshock and figure out how to hide the wiring the best I can.
B) use the current stock swingarm but weld on brackets to attach dual shocks. The shocks would be at a sorta weird angle I think because the stock swingarm is a little shorter.
C) try to find another swingarm that is already set up for dual shocks that will fit.
D) Maybe use spacers with that dual shock swingarm and get it to fit snugly in my frame. If anyone knows of another that will for sure fit, let me know.
E) Swap the pivot point on the swingarms so I'll have the dual shock swingarm but with the stock pivot point. Not sure how difficult that would be to align properly and weld safely.

If anyone has any feedback on the easiest way to turn this into a Dual shock setup, let me know!

I know those pictures are probably sideways, but it would take me forever to redo them, so, sorry in advance.

Thanks everyone!

 

[bcware]

I would keep the monoshock and just make a tail section with enough room to hide what you want.

 

[bentwrench]

You may want to post on the XJBikes.com website to see if anyone who is running a dual shock XJ550 or so can measure their swingarm. XJ550 is sort of the next biggest bike, but more importantly, they kept making them after 1984 AND they also switched them to dual shock (In 82 and 83, it seems Yamaha was running monoshocks on all their standards and cruisers, including the Virago, but then everything goes to dual shock in 84.)

That said, almost any swingarm change will involve spacers, probably at the pivot, and possible at the rear rotor, to make sure that the chain lines up without bending.

 

[frwinks]

never liked round front frame tubes with boxy swingers. Make the spacers from your 82 arm put them on the 81 swinger and run with that. You obviously can weld, so that would be the easiest way to go IMO.

 

[cafenewb]

BCware - I already have my seat made and read to put on. It's a really minimalist seat so i'm not sure I wouldn't be able to hide the battery in it like a cafe rear hump would allow.

frwinks - That's how I feel as well. something about the round tubing mixed with square tubing just doesn't look right.
That does seem like the easiest, but I'm just not confident in my ability to weld it on 100% straight. I'm not sure what the tolerance would be for something like that. I assume it could be off a tiny little bit without much trouble, but when it comes to something that could physically harm me, I want to be 100% sure.

I'm down to just use spacers with the dual swingarm. Does anyone have recommendations on where to buy some, or easy ways to make them, or is my best bet just having something machined?

Thanks for the feedback guys. I'm start to get anxious to ride this baby (even though there is still a foot of snow in my yard).

 

[frwinks]

What is the difference in width between the two? I would just cut what you need off the 82 unit, chamfer the edges, sacrifice one set of bushings to line things up, clamp using the big bolt, some washers, tack, remove bushings, re clamp, weld shut, grind, put a set of bronze bushings, put on bike, don't look back

 

[cafenewb]

^ I think that's the answer. When I get home from work maybe i'll tackle that. Since it fits so tight around that bushing it would be much easier to line up than removing the whole pivot point.

Thanks for the feedback. I'll post some pictures once I get going.

 

[cafenewb]

Ah dammit. I'm just going to rock the stock one and make it work. I'd have to get new spacers for the wheel to make it fit into the narrower swingarm for the 81.

I just need to spend more time hiding the wires. Any recommendations for that, since I can't hide them under the seat? My first option is to just mount the regulator/rectifier to the battery box, but not sure where to put the bulk of the wiring.

 

[jboyer]

wire loom works good for disguising wires cuz on my bike ther is only a couple visible wires

 

[cafenewb]

I don't really have any intent of turning this into a build thread, however, I just build my seat from the ground up and i'm pretty happy with it. First time sewing vinyl and first time making a seat for anything. I think it turned out.
16 gauge steal for $6, vinyl was $4, thread and misc. things were $4, batting for the ribs was $6 and rivets were $6.
For about $26 I'm happy. Not the best, but could've been worse.

 

[Charles]

BCware - I already have my seat made and read to put on. It's a really minimalist seat so i'm not sure I wouldn't be able to hide the battery in it like a cafe rear hump would allow.

Have you looked into these?

 

[ksqrly]

Chalres have you used one of these? Is 120 CCA enough to turn the starter motor?

Cafenewb-I welded a piece of sheet metal under my frame and have a hinged door on top to open and close to get to wiring. You might be able to make it work the same way

 

[Charles]

Yes sir. I'm using one right now. Granted, 90% of the time I kick her over, but elec start works fine. Unless it's very cold. Those batteries actually like to get warm by having a load put on them. So if it is cold, a couple of "warm up" cranks might be needed.

You can read up on them and decide if it's for you. There's plenty of people who use them.

 

[ksqrly]

Ya I checked the website. Those are pretty cool. I would probably go for an 8pack but it is still much smaller than the stock. Unfortunately I already bought a battery. I thought the bike would need more CCA than 150.

Im still a bit sceptic because I dont have a kickstart. The battery I bought is quite a bit smaller than stock and it has 240CCA. I think I would have preferred the Anitgravity 8pack to the battery I bought, but it is quite a bit more expensive than the one I bought.

 

[Charles]

Yeah, they're more expensive, but if space is an issue...
And there are other brands out there, I just grabbed a pic off Google. You can probably get a 4pack for $70, if you shop around.
I think an 8pack is overkill. My friend uses an 8pack for his 1200cc Harley, but if you live in colder climates and don't want to have to deal with the extra 30 seconds it might take to warm the battery up, get the 8pack.

 

[ksqrly]

Ya pretty cold up here in Utah. I was just instructed by people I trust that I should bet at least 200CCA, so I went with it. Its good to know that people are having good success with these smaller batteries

 

[eaterofsmoke]

So a question, I have the same bike, wrestling with the same issue. Would it work the cut the upper portion of the swing arm that connects to the mono shock, and create mounts for dual shocks about where the bolt is at the rear upper point of the triangle in the suspension? I have been contemplating doing this, but wasn't sure if the frame would hold up to the dual shocks pushing on it, and if the swing arm would lose to much strength in the modification.

 

[cafenewb]

^ That would work. I looked at doing that but just didn't want to mess with it. I ended up keeping the monoshock and it's working out so far.

 

[markjs]

Yeah I get that the look isn't as cool, but the handling to me is so much better with the monoshock and why add trouble for yourself? Might try finding a way to wrap the original with something to give it a rounder look.