chain conversion

[dingleberry]

Ok all the sensible people, take a deep breath, count to ten and bear with me.
I am going to convert my shaft drive xz400 to chain drive. I know, it's higher maintenance and all that but I just want to. Haven't done anything like this before so if I pull it off it should give me a sense of achievement, that's reason enough to me. Oh and I blew the money for my tig welder (for frame mods) on a couple of old bikes. Anyone know if there is a "bike collectors anonymous" program anywhere I can sign onto?
I have the general idea of what to do but because I'm pretty new to engineering I have question.
An outer housing seems the way to go but I'm a little unsure how to measure accurately so the bearing in said housing lines up exactly with the output shaft from gearbox. If you guys have seen a chain conversion or picture of one this should make sense hopefully. I saw some pics in the ROV newsletters so I'm assuming most will know what I'm on about. Please assume I'm clueless and give me the basics or a link to an appropriate site. :-[ 

[The Prophet of Doom]

There are pics and descriptions of John Clemens' chain conversion on this forum

[charlie h.]

Once you get the chain conversion done, find an XS400 Seca (82-83) rear wheel to match the Vision front... It was chain drive!

[The Prophet of Doom]

An outer housing seems the way to go but I'm a little unsure how to measure accurately so the bearing in said housing lines up exactly with the output shaft from gearbox.

I'd drill the housing and fit the bearing first, fit on to the shaft, then transfer punch to locate the drilling spots on the engine casing.  I love transfer punches as they pretty much always give accurate results. You can make your own out of old drill bits, bolts etc by sharpening in your lathe - or even a drill

[dingleberry]

Ah it's just like you said the other day POD, there will be an easy way to do. The way you describe makes good sense, I was thinking from "inside the box" i suppose. So I'll locate on shaft, transfer punch, probably dowel and maybe use studs in the casing, then mill outrigger bearing housing to shape. All sorted in my head now, just need to get down to business.
I think I will be going for alloy rims and spoke wheels for weight saving and looks but also good to know about the 400 seca wheel.   

[The Prophet of Doom]

We need to collaborate on the spokey wheels

[fret not]

To make the chain conversion the "middle gear" on the end of the counter shaft is machined and fitted with a sprocket.  There is no need to be adding bearings and shafts etc.  This has been done several times some years ago when the XZ was raced ( John Clemons, Eddy Wilbanks, and our own motoracer8, among others)  The Eddy Wilbanks XZ was made into a 750, but that required changing the stroke of the crank as well as larger bore.  More usual is just boring the cylinders to 650 and opening the top of the cases so the larger cylinder sleeves fit into the cases.

[The Prophet of Doom]

Here's John's post about chain drive conversion
http://ridersofvision.net/rovforum/index.php?topic=11572.msg104853#msg104853

The thought of a 650cc vision gets me wet.  What a shame no-one itemised the changes needed.

[dingleberry]

Removed the shaft drive from parts bike today. In excess of 6kg, mostly rotating mass. Maybe there is hope for the 400 yet eh?
My goal is to have my 400 whip a stock 550.

[QBS]

John Clemons (I think?) once said that 650cc Vs were "all bore, no stroke".  I'm thinking that no replacement cylinders or liners were needed.  Just bore the stock cylinders to max bore needed to get the 650 displacement.  Getting the correct pistons and rings is the hard part.

[The Prophet of Doom]

Interesting chain conversion on an XS - with pretty pictures
http://www.xs11.com/forum/showthread.php?t=35862

[fret not]

Need new cylinder liners to get to 650cc, as stock ones would be too thin after boring.  Also need to enlarge the holes in the cases where the liners slip in.  It means taking the motor all apart to bore the cases.  It's quite feasible to make it a 650 if you want a larger motor, but making it a 750 is considerably more work and expense.

[Rick G]

I talked to John 12 years ago about the procedure needed to go to 650 cc and Fret has it right. Jefferson  referred me to  a fellow who had raced 750 cc Visions. The cranks were custom made  by a foundry in his town. there were 3 total. he had one left and it was in his race bike , which sat on his show room floor  and had not been run in years. He wouldn't sell the bike  either.
He used special JE piston and rings , which have long been out of production .

[dingleberry]

Jeez that's not going to leave much material in the barrels of my 400. Are water jackets really necessary ::)

[The Prophet of Doom]

What about using 550 barrels as a starting point?  That would be far more sensible.

[dingleberry]

Ok, now where would I get a couple of those? Ready to do a deal on those injuns?
Maybe I could bring my empty frame around and trial fit one to be sure...

[The Prophet of Doom]

I'm reluctant to get rid of any bits till I'm up and running
We can take measurements though

[dingleberry]

Long time - no action. I've been busy gathering tools and getting side-tracked learning how to use them.
Today I removed outer gearbox bearing where shaft comes out. The 4 countersunk screws holding the retainers in place were a bugger to get out. They are dot punched to lock in place and a large torx head which I don't have tool for. Not that it would matter, these were probably done up with a rattle gun, which I also don't have. I drilled a suitable hole in head of screw/bolt and used a screw extractor/ezi-out. May have to make those screws down the track..
Anyway it's not what I expected in there. Photo:

[dingleberry]

I should have shown photo of side of bearing seen from outside, it looks like an open bearing but I turned it to show the back(inside) because I didn't expect it was like this. There's two steel rings still in place behind bearing. What purpose do these serve? There is also an oil hole in side of bearing housing. Does a gearbox need to breathe or is it safe to seal these holes up which seem to lubricate the bevel gears?   

[dingleberry]

I have a couple of pics for you showing my proposed new swingarm. It is very similar in all dimensions/angles (yam xt250 '81?). Now question time. The vision swingarm has wide mounts for obvious reasons compared to the new one. What I'm wondering is do you think the narrower mounting (bush area) will have any adverse effect on handling perhaps due to extra twisting force (guessing)? Any suggestions regarding modding in this respect?