Good Heart, Bad Intentions: another build thread

[osteoderm]

Most 90/90-19 tires are front tires, not built to withstand rear wheel stresses.

Completely agreed... but I'm always open to learning about the "exception to the rule"...

I went with an 18" rear mostly because of the larger selection of easily found street rubber.

The more I read up on tire sizes/availability, the more I see the wisdom of this! But there's a certain something about that 19" rear that revs my engine... 100/90-19 fr & rr looks like the direction to head in.

 

[daroberts3]

I hadn't yet convinced myself to go for the rear disc conversion, but a decent deal on another 19" D.I.D. wheel came up on eBay, so...

I know these high-flange rims aren't to everyone's taste, but I like 'em. Light, strong, and annoying to clean . I was originally keeping my eyes open for another bare front hub, thinking of converting the stock 18" rear wheel to disc, but now the 19" front and rear combo is sticking in my head.

A 18" rear / 19" front combo sure is easier for aesthetic tire choices... I like the look of the 90/90-19 for a front tire, but what to pair it with in the rear? Seems like I'm stuck with 100/90-19 front and rear... Or... what's the prevailing wisdom re: running a 90/90-19 on the back?

I keep imagining that there's something like a a 120/70-19 tire available for the back. Yeah, right.

I found several 120/70ZR-19 Front tires in my Parts Unlimited catalog. Avon, Continental, Dunlop, Metzeler, Pirelli and Bridgestone all make this size. Avon Cobras wwould look sweet on your bike. They are all radials. Common size for H-D V-Rod front wheels. All of them retail around $200.

 

[pregrid]

Most 90/90-19 tires are front tires, not built to withstand rear wheel stresses.
A 100/90-18 on thr rear will run well with a 100/90-19 on front.
Leo

No offence, but I'm not sure where that thinking comes from. What kinda HP are we talking about? 50?

 

[osteoderm]

I found several 120/70ZR-19 Front tires in my Parts Unlimited catalog. Avon, Continental, Dunlop, Metzeler, Pirelli and Bridgestone all make this size. Avon Cobras wwould look sweet on your bike. They are all radials. Common size for H-D V-Rod front wheels. All of them retail around $200.

Come to think of it, I had seen those somewhere. The Avon Azaro 110/80-19 are interesting too. I'm unsure about running tubeless-type radials with tubes on spoked wheels, however, and these 19" rims are way narrow for a 120 radial (at least going by Avon's own specs).

I'm leaning towards Avon Roadriders in 100/90-19 size. universal f/r fitment, bias, modernish tread, about $100 each.

 

[osteoderm]

No offence, but I'm not sure where that thinking comes from. What kinda HP are we talking about? 50?

I read all sorts of "front-specific fitment" caveats on tire manufacturer websites, but encounter little hard support. From what I've seen, it's less about withstanding stress and more about contact patch and slip angles and such. Unless there's some specific safety issue at work here that I am unaware of, I'd give it a try.
The greater issue to me is one of tubes, radials, narrow and/or spoked wheels, and all the interplay between them. There's a ton of opinion going every which way out there, not much of it conclusive. I'm willing to try some "different" ideas with this build, but spending $300-$400 to experiment with modern tubeless low-profile radials for my antique narrow spoked rims is getting out of my comfort zone.

 

[plane_ben]

Go to the Coker site they have all kinds of old school tire sizes. All the way to 28". They only seem to be short on 23" choices, which is what I need.

 

[yamaman]

Akront style 18" rear and front, with Dunlop TT100gp tyres, is the ultimate IMHO. Also, I can vouch for Mikes needle roller swing arm kit, quality gear, just the instructions were in German, if thats still the case, the translation is still on 650rider. The needle rollers probably should be pulled and lubed on a anual basis, but thats a low price to pay for IMHO the best set up there is. Love your work brother, I hope you can maintain the rage to the bitter end. Merry XSmas and a fantastic 2012, cheers
PS if you want to run a front tyre on the rear, run the direction arrow (if its there) facing the wrong way.
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[XSLeo]

There are some tires out there that are a universal fitment. I think Dunlops K70/k81 tires are. I have a 130/90-16 off that came on my 16 wheel that is.
When tires are made the way the belts are wrapped and over lapped make the difference. Run the wrong way and the belts can come un done, starting at the overlap.
Lets say you do try running one backwards and it does self destruct and you get hurt. Will your insurance company pay off if you are running the tire backwards? Is it worth the risk?
Leo

 

[yamaman]

Leo, yes ideally a tyre should only be run as designated, I guess the "look" can become more important than anything else sometimes. However, a tyre wont fall apart just because its spinning the wrong way. Directional arrows (NON radial type tyre) is mainly there to denote the position of the joint overlap. (another reason could be tread design). One direction for front fitment, the joint is positioned to be most resistant to braking forces, put the same tyre on the back the other way around to resist accelerative forces. So, if you must use a front tyre on the rear or vice versa, run the arrow the appropriate way. Cheers

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[osteoderm]

Well, all the pondering on how best to drill and/or waterjet my stock brake rotors has come to an end...

Not sure if the new direction my front-end has suddenly taken off on will cause me joy or frustration, but like Yamaman says, I'm trying to "maintain the rage to the bitter end".

 

[osteoderm]

The rotors are cleaning up nice with Flitz, Scotchbrite, a fine stainless toothbrush, and patience...

 

[Travis]

Nice rotors. What are they from?

 

[osteoderm]

Okay, before getting into this front-end any further, I have to give due credit to Richard Pollock for the basic "recipe". I'm trying to follow the basic idea described here. I'm no Mule, and I've never expected anything to be "bolt-on", but it sure is a great help knowing that someone else has made the general arrangement work successfully before.

First up, I found a set of 1976 TT500 triple clamps:

The Good: The TT500 triples are crazy lighter than the stock triples, mainly due to the aluminium lower. They're a three-piece design instead of two, which makes the (necessary) modifications much easier. The handlebar mounting is built-in and low-profile. There's a touch more fork offset, which in my case is a good thing. The upper clamp has a touch less downward offset, which means the tubes mount a little higher overall. Finally, the stock bearings and seals are a direct fit.

The Bad: The stem is too short for the XS headtube. The clamps are 36mm (which is good or bad, depending on your situation). The steering stop tabs are facing the wrong way, which will necessitate a different stop arrangement on the frame.

I'm still working out the best way to tackle the biggest issue of overall length. The stock stem can be machined out of the stock lower, then somehow bolted into the TT500 lower. However, the TT500 stem is lighter and hollow, and I'm thinking it would be easier to lengthen it than deal with modifying the stock stem. At least the top clamps are a direct swap.

Here are the forks, 1990 FZR600:

They're 38mm and conventional, so they won't look too out-of-place on my bike, unlike the Ducati 900SS units a friend offered to give me. The stock 34mm TX650 forks in the pic have been lowered approx 1.75", which makes the FZR forks look way too long. They're actually not impossibly overlength for the application, but they will still need to be lowered.
I pulled a top cap, removed the spacer, and fully-compressed one leg for measurement. It looks like I can run them with about almost 2" of tube above the top triple and not hit anything at full compression. That's a far from ideal situation, but at least I have room to work with.

This is the best part, a Christmas miracle from eBay... I pulled the spring, poured out the oil, and this little rascal dropped into the bucket:

I actually exclaimed "Hot Potatoes!" out-loud when I saw this, which has to be the weirdest, most random thing I have ever said to myself in the shop. Is it what I think it is? Oh yes, I do think it is!! Further to that, closer inspection of the springs reveals a distinctive shot-peened surface I haven't seen on a stocker... Springs and emulators are worth way more than what I paid for the fork legs!

Well, I still have to get the forks apart for seals (the wipers are cracked, and I never trust a second-hand oil seal), but things are looking good.

 

[osteoderm]

Nice rotors. What are they from?

1992 FZR600. These aren't really in the greatest shape, but they'll more than serve for assembly and mock-up, and of all the pieces of this swap, they're the easiest to find. Most importantly, they're a direct bolt-on to the stock hubs.

 

[osteoderm]

The good news is that the $40 calipers I scored on eBay look decent, with no scoring/pitting, and usable pistons. the bad news, there's four times as many pistons/bores to clean and re-seal... broke 'em out with a grease gun; worked great, but what a mess.

Don't know where to start shopping for these bits... There's no MikesFZR Quick search is showing like $60 for seals! Oh well, can't cut corners on brakes.

 

[pregrid]

There's no MikesFZR

 

[osteoderm]

Still trucking along, but no pics to post... unless people would like to see pics of parts being de-greased? Ummm, didn't think so!
The new forks are tore down, brake parts all cleaned, and new seals ordered. PMA from Hugh boxed and on the way. Lots of little bits and pieces showing up in the mail; time to get back to work to pay for it all!

 

[osteoderm]

Been a little distracted this past week... my bike has a temporary stablemate in the shop:

Helping a friend tear his '69 Triumph down for painting. Should be back together by the end of the weekend. It's amusing and informative having the Triumph and the Yamaha side by each, an interesting comparison!

I did manage to get one major piece done on my own bike. The PMA kit from Hugh is installed! Decent kit, nice fits, but I'd say it's more of a 98% head-start than a 100% drop-in deal. The wiring leads from the stator are inconsistent (nothing Hugh or anyone can do about that), so you have to juggle things around a bit to get a decent wiring path.

In my case, I filed a good chunk of the modified stator mount away in order to have the wires run out smooth(er) and make room for the supplied clip:

I also swapped out the supplied Phillips machine screws for M6x25 buttonhead allens with stainless washers. As Hugh advises, plenty of red loctite all-round! I had to track down a woodruff key and substantially modify it to fit between the metric shaft and standard rotor (a long frustrating process that defeated my attempts to photograph it!), but all turned out excellent in the end. Overall excellent fits for the adapter and machined stator mount, all new parts well-packed and inspected prior to shipping. I'd fully recommend this one!

I swore up down and sideways that I wouldn't touch the engine this season. Sure, I want to, but with under 8k original miles on the engine and a whole plateful of other chassis mods to finish, opening up the engine seems like a fool's errand right now. I'm limiting myself to the PMA, a Pamco, and the hydro clutch; everything else can wait!

Managed to get Robert Ward on the phone this afternoon. Great guy, very accommodating, and well worth the patience required to get in touch with him. Ordered the 19" rear disc conversion kit and a couple other bits. The "big ticket" items are slowly getting checked off the purchasing list!

 

[yamahawife]

That 19" conversion kit is the shiznitz!! And yeah, Robert is cool to deal with.

 

[osteoderm]

Fingers and toes crossed that I'll be able to get some more machining done this weekend. Spent the afternoon preparing some pieces.

Here are the stock TX650 trees:

Here's the lower triple-clamp and quill, with the quill from the TT500 triple placed alongside it:

The TT500 quill is obviously too short overall. The critical distance is between the two bearings; the shorter top end and threaded area are fine, as they work well with the new upper clamp. To make the middle longer, I need to cut it apart...

I cut it in half at an arbitrary point in the middle, away from sealing and bearing surfaces. I then faced the cut ends square, and moved on to the plug that lengthens the quill. Unlike the stock quill, the TT500 one is hollow, so the cuts and machining go quickly.

I made the plug from leftover stock from my swingarm linkage pivot. It's 1" precision-ground, and I had already drilled this piece out as a test for the swingarm piece. The hole is 1/2".

Here, I've pressed the plug into the upper section, and pressed the lower section back into the lower triple-clamp. The fits are more "tight slip" than press-fit. The bevel left on the slug will accommodate the finish welding. Now that I have plenty of length to play with, I'll make a measurement and machine the other end of the plug to match.

Of course, after all this, I'm fully expecting somebody to point out how there's some stock-application quill out there that is already the right length and will fit the triples...