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BLACK BELT
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6,918 Posts
Discussion Starter #41
Aprilia RXV swingarm looks great:




But the RXV frame looks like shit (even if it's stiffer and lighter), I'd rather use the old RZ350 frame! :LolLolLolLol:

 

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BLACK BELT
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6,918 Posts
Discussion Starter #44
Well, I'm probably getting ahead of myself - but I just found an Aprilia SXV swingarm for sale.

I don't want to buy it yet, because I don't know the length, width, and where I could attach the upper bushings on the RZ350 dogbones (L-brackets) to the Aprilia swingarm.


 

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re-tarded
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1,283 Posts
If you don't want to hack up the stock bike in great shape, I've got a currently CA registered 85 RZ350 in need of a new bottom and top end (and forks, and some other stuff) that I'd let go reasonably cheap.
 

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BLACK BELT
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6,918 Posts
Discussion Starter #46
Man, I'm so insane sometimes. :nuts:

In negotiations now to purchase some new, and near new condition Aprilia SXV parts. Frame, swingarm, forks, and some other stuff.

These parts are EXPENSIVE, but very difficult to find, except on a complete used bike. If I can get enough good quality used parts, then maybe I can add the custom parts and build this thing without breaking the bank.

Purchasing this frame is not a lock, yet. I think the seller wants to sell it to a race team, or aprilia owner who needs it. We'll see.

I know I said the frame is ugly, but I didn't expect to be able to get one, and the other parts I need. Ugly or not, it would perform miles better than the RZ-framed motard.
 

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Simplify
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170 Posts
If you could pull off a SSSA with a bling old school caddy spoke wheel I bet you it would look absolutely ridiculous and handle like shit but you'd be the only one in the world with one. Someone photochop that shit.
 

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BLACK BELT
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6,918 Posts
Discussion Starter #49
SSSA + spokes would be fun
Well, this whole thing started with the SXV swigarm. I would much rather have the SXV swingarm than any SSS.

The main problem I have with SSSs is that they are much heavier than a standard arm, but don't perform as well.

I will be doing a SSS on my NS400R project bike. (Believe it, or not - I'm negotiating now with someone selling a one-off SSS conversion for the NS400R). The problem is, he doesn't want to sell all the parts that go with it and they are a BITCH to fabricate (I know the guy who originally made them).
 

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BLACK BELT
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6,918 Posts
Discussion Starter #50
Fundamental problem with using the Aprilia SXV frame & RZ engine swap.

The Aprilia runs a V-twin engine (narrow). The RZ350 engine is a parallel twin (wide). The Aprilia engine sits inside the frame rails. The RZ engine is much wider than it's OEM frame, and much wider than the Aprilia frame.

I can see that the RZ engine would need to be placed a few inches forward from where the Aprilia engine is normally. Besides moving the weight forward on the bike, it may cause problems with tire/exhaust pipes clearance and radiator mounting.

Have to look at this more closely. Tomorrow, I'm going to an Aprilia dealer - hopefully I can get some actual measurements.
 

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BLACK BELT
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6,918 Posts
Discussion Starter #51
Hardly had any sleep for the past 3 nights because I can't stop thinking about this project (just don't want to miss out on those parts, if I can use them). Today, I drove out to the Aprilia dealer who let me check out the 450 SXV (same frame as the 550 SXV) It's a demo bike, so I could have taken it out for a thrashing, but I was too tired to care.

I only took a ruler, because I didn't think there would be a chance that the RZ engine would fit. But I was wrong. I'm not saying it will work, yet - but I'm not saying it won't work. It's extremely close to not working, though.

I'm going to try to get back to the Aprilia dealer tomorrow, maybe armed with a template or measuring tool that will help me determine if it's worth a shot. The upper engine mounts are extremely close (maybe too close) to where I think the RZ engine head will be. The engine may just be too long, as well, not sure yet.
 

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BLACK BELT
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6,918 Posts
Discussion Starter #52
I'm going to try to see the bike again today, armed with this template. (I didn't finish the front of the head/cylinder, but I think it's okay for eyeballing the frame clearance.)



 

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BLACK BELT
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6,918 Posts
Discussion Starter #53
Went to look at the Aprilia again.

The engine swap isn't looking good. The distance between the upper frame mounts on the SXV frame are about 6 3/8 inches apart. It looks like they will hit the intakes on the cylinders which are almost 7 inches wide.

If I were able to shave 5/16 inch from each mount, I think there would be enough clearance, but I would need another 1/8 inch per side for a stainless insert - a total of 7/16 inch . Not sure if it's possible to bolt in a stainless plate to reinforce the smaller mount ( I doubt it).

I didn't get the O.D. of the upper mounts, so I'll have to go back and measure again.

Like I said, it's not looking good at this point. :jpshakehead.sml:
 

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BLACK BELT
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6,918 Posts
Discussion Starter #54
For mounting the front of the RZ engine in the Aprilia frame, I think I could weld brackets to the steel part of the frame to hold two front brackets which would go to the front RZ engine mounts and then to the outside of the aprilia front frame mounts.

The engine weight would be supported by the upper steel frame, the aluminum frame mounts would just triangulate the bracket. I also might be able to use the front brackets to mount the radiator.

The front brackets could be made of round aluminum tubing to match the front of the frame, or made from billet aluminum cut to match the rear of the frame. I think the tubing would look better, though.



Still have to see if there is enough room to cut down the front aluminum brackets on the Aprilia frame.
 

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BLACK BELT
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6,918 Posts
Discussion Starter #55
For mounting the rear of the RZ engine in the Aprilia frame, I'm wondering if it's possible to weld a couple of bosses or tubes onto the back of the RZ engine so the swingarm pivot bolt can go through it, like the Aprilia engine.

Another idea I have is to run a bracket from the mounting points on the rear upper RZ engine to the Aprilia swingarm pivot.
 

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GURU
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8,827 Posts
not that i want to rain on your parade because its a cool project but dont get too far ahead of yourself:)

Part of that frame is cast and may or may not take kindly to modifications if you need to mod/remove material at the rear where the engine goes. You may have a pile of junk before done. I would be willing to bet you could resell some of that stuff for top dollar and buy a complete 4 stroke enduro like an old xt and be much better off with the motor swap/frame mods. Also one thing to consider, even if they dont crack down on the motor swap, insurance for say an 86 xt250 would be much cheaper than an aprilia anything ;)

as a note the 5.5 version runs a 180 rear. i think the 4.5 runs a 150. Dont know for sure but i think the rear arms are different.


I think its a cool project for sure and its certainly one of a kind but dont forget to consider other options.

DRZs are cheap and plentiful and steel frame. Yamaha xt225s are very cheap. KLR250, Any old XR or XL.
 

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BLACK BELT
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6,918 Posts
Discussion Starter #57
not that i want to rain on your parade because its a cool project but dont get too far ahead of yourself:)

Part of that frame is cast and may or may not take kindly to modifications if you need to mod/remove material at the rear where the engine goes. You may have a pile of junk before done. I would be willing to bet you could resell some of that stuff for top dollar and buy a complete 4 stroke enduro like an old xt and be much better off with the motor swap/frame mods. Also one thing to consider, even if they dont crack down on the motor swap, insurance for say an 86 xt250 would be much cheaper than an aprilia anything ;)

as a note the 5.5 version runs a 180 rear. i think the 4.5 runs a 150. Dont know for sure but i think the rear arms are different.


I think its a cool project for sure and its certainly one of a kind but dont forget to consider other options.

DRZs are cheap and plentiful and steel frame. Yamaha xt225s are very cheap. KLR250, Any old XR or XL.
Yeah, if the Aprilia won't work, I'll probably do the RZ frame with the Aprilia swingarm, linkage, rear shock, subframe, forks, wheels, etc.
 

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BLACK BELT
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6,918 Posts
Discussion Starter #58
My main fabricator, RGVSteve, says he's ready - and to hurry up and buy the shit, already! :D

He's way more confident than I am.

Of course - I'm only risking thousands of dollars, no big deal. :doh:
 

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BLACK BELT
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6,918 Posts
Discussion Starter #59
Went to see the Aprilia again.

The good news is - the aluminum mounts on the frame are approx. 8 inches on the O.D. That means I should be able to take off enough material to squeeze in the engine.

The bad news is - the Aprilia engine is supposed to bolt between those 2 mounts, which makes the frame stiffer. There may or may not be enough room to run a brace from one mount to the other.

More bad news - I eyeballed the location of the RZ countershaft sprocket center and it looks higher than the swingarm pivot on the SXV frame. That means the engine might need to be lowered a little. That will decrease ground clearance - and it won't look as good.

I still think there is A LOT of potential for a wild ride, so for now - I'm going ahead with the project. I'll do my best to build the motard with high-end and custom parts like on my streetfighter project.
 
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