Hey guys, yup I'm still a Visionary, just been away for awhile. I seem to have some time on my hands of late though....
So I'm finally doing an '83 fork swap on my '82 Vision. I checked some part numbers to see what may be able to be swapped and noticed some differences. The spring for instance is a different number. Since the '83 has air assist, is the spring a tad softer than the '82? The damper rod (cylinder, frtfork ,per the parts list) is different so I'm guessing different sized holes for the oil to pass through? Also the stanchion (inner tube per the parts list)is a different number.
I've yet to disassemble the two and visually compare them. Maybe some of the differences will become apparent then? However, it doesn't hurt to avail myself of the valuable resource this forum is, so I was wondering (hoping) some of you guys had some insight on the differences between the 2 forks. Thanks.
Rick ! Thought you must have died or gone to prison/assylum/etc. Welcome back
We don't have 11H/J models here but I've done three 14X - XZ400(air)->16R(airless) transplants which may apply.
I ended up retaining the 16R lowers, dampers, springs and spacers, and using the 14X inners and caps
A little air makes the world of difference.
- Biggest diff was that the 14X air caps are threaded differently - same pitch but they are longer and sit deeper than the non air 16R caps. The inners have to transplant with the caps
- The 16R had longer but softer progressive wound springs. X14 has much shorter but harder even spring windings
- 16R had a shorter spacer, 14X at least 30mm longer. With the longer air cap, I would have chopped the spacer, but needed a little more pre-load anyway as I'm not a 65kg japanese boy
- Didn't think to measure the holes, but dampers were dimensionally the same
- Chrome quality better on the later 14X model inners
On the super-mod, I drilled out the dampers and added a pair of racetech gold valves
CheersR
Thanks for the reply Rohan. Since the accident a few years back with my GPz it's been a struggle to regain my enthusiasm for all things bike related.
I located a pair of '83 RK forks over the winter but they have bent inner tubes. I was hoping to just swap with my good RJ inners and use the RK air caps but apparently the cap thread depth may be different. It's kinda cold and miserable today so I doubt I'll get out to the garage but I'll report back with what I find. I'll measure the damper holes and post too. I have a set of Progressive brand springs I'll probably use but it will be interesting to compare the spacer and spring lengths once I get the RK forks apart.
If your fork inners are not kinked they can probably be straightened with a hydraulic press. This was a common practice in the 70s & 80s when I worked in dealerships. A bit of skill/experience is required by the press operator, but usually good results and much less expensive than replacing parts.
Rohan, FYI, the oil holes in the damper rod seem to be 5 mm in both RJ/RK forks. The dampers seem to be identical in all respects so I don't know why they have different part numbers. Maybe I'm missing something.
The springs are pictured below with the '83 RK on top, '82 RJ in the middle, and Progressive brand spring on the bottom. The Progressive and RK are vari-wound with the RK being shorter. The RJ spring is straight wound and shorter than both the RK and Progressive. The RJ spacer is longer than the RK's. Including spacers (Progressive brand uses none) and in ascending order of overall length it's RJ, Progressive, then the RK. The progressive spring kit is the same part number for both years.
The fork caps are different as pictured between the 2 models. The fork inners are the same length between the 2 models but differ as dictated by the caps. The RK threads start further down and are longer i.e. more thread engagement.
fret not, I've straightened quite a few forks in my day and these are good candidates as the bend is slight. Sadly, I no longer have the equipment (easily) at my disposal and would not spend the money on new inners or having them straightened at a shop. I bought these forks at a price knowing of there condition. I would have used my inners and the 'RK air caps (if they had fit) for aesthetics only as I won't be using air.
Live and yearn. 8)
Quote from: fret not on April 28, 2020, 01:03:04 PM
Live and yearn. 8)
Oh, if only that were true. The lessons I've had to re-learn...
One of my brothers loaned me this basic press. He was gifted this jem in pieces with a kinked hose and non-functioning pump. In that condition it has remained languishing in his shed ever since. After some time on YouTube learning how to rebuild the pump and valve mechanisms (O-rings) I got it together and functioning. The hose seems to hold pressure but this operation doesn't ask much of even this system's limited resources. Fingers crossed.
I tested the admittedly sketchy setup with an old fork tube/leverage bar from my tool kit and it seems to perform OK. I'll work on straightening the bent tubes soon.
I am in the process of putting my 83 front end back together after painting, rebuilding brakes and installing tapered steering bearings.
My fork springs are not progressive wound like in the photo above, they are straight wound. Humph.
Well, that is interesting. If the spacer is 3 3/16" and the spring is 18 1/4" you might have '82 components in there.
Are you the original owner? If not, perhaps the forks have been altered at some point.
I am not the original owner and the gentleman I bought it from probably didn't modify anything. He bought it as a spare bike and never did anything to it.
My springs are 18.75 inches long and the spacer is 3.75 inches. I just measured them yesterday before putting the forks back together. The Haynes manual says they should be 19.04 inches long but the Yamaha 11K supplement says 18.7 inches long. The photo in the 11K manual supplement shows a straight wound spring.
I don't see your location listed - is this bike from the North American market?
Yes. It has been in California all of its life.
Made some progress recently. By clamping the two large blocks together and drilling through the meeting line I got a nice shape for the tube to nest in. A smaller one for the top to push against lets the tube rotate in place rather than walking off center. Spinning it with a small load helps quickly find the high spot in between adjustments. A little mark with a Sharpie lets you know if your chasing the bend around or making progress. Got one tube done but I was a bit worried about the top block splitting right half in two and launching a piece at Mach 4 towards me.
To test if the tubes are straight, you can lie 2 of them together and rotate one 1/4 turn at a time using a feeler gauge cantre and each end to see if there is any space between. When you've done a full rotation of one, then turn the other 1/4 turn. Repeat till you've rotated one 4 full turns and the other one turn. Easy
Good tip, thanks. The system I described is to get you close without having to leave the press station.
Time for an update... The tubes have been successfully straightened and I begrudgingly returned the little press to my brother.
The forks and wheel have been dry fitted to begin the process of creating an adapter plate to fit the 2 pot caliper to the right fork leg. I have a spare master cylinder and hose installed to facilitate holding the caliper in place on the rotor to create a template. This has me thinking about which hose arrangement is better - 2 hoses running from a master cylinder one each to the left and right caliper or, one hose leading to a caliper and then a shorter hose run from there over to the other caliper. Any advantage to one over the other?
My vote would be for symmetry or a two hose setup, one to each caliper.
Noted, and I am a big fan of symmetry. :)
Quote from: Rikugun on June 01, 2020, 07:06:14 AM
This has me thinking about which hose arrangement is better - 2 hoses running from a master cylinder one each to the left and right caliper or, one hose leading to a caliper and then a shorter hose run from there over to the other caliper. Any advantage to one over the other?
Galfer recon that the two line have better brake feel, but I've run both, and noticed no difference. I thought the two line systems were a bit more tolerant of the fittings being rotated incorrectly. They do bleed a bit more easily too. Air gets trapped in that Y piece.
Thanks for the input Rohan. After I posted and gave it a bit of serious thought the first question I had was the bleeding process. That bit about the ability to "twist" the lines into alignment is a good point too - the longer the better. I knew there was a reason why I liked having you around here.
What about the added volume of fluid that has to be moved with 2 large lines? Any thoughts on that? I thought no real effect but then exaggerated the lengths as a thought experiment, say to 10' each. Would that effect the feel at the lever? The culprit would be lack of efficiency/loss due to blow-by at the master cylinders piston. Cars have much greater length of line and hoses but they also a larger master piston. Maybe I'm over-thinking things. Again.
It's really not the length of the lines, but the relationship of master to caliper piston size. Cars have much larger pistons in their calipers.
Indeed. I had quite a learning curve in that regard when I did my first single disk upgrade. The SV650 type caliper I used didn't have sufficient piston area to make the correct ratio using the stock 1/2" master.
Quote from: Rikugun on June 02, 2020, 06:51:54 AM
Thanks for the input Rohan. After I posted and gave it a bit of serious thought the first question I had was the bleeding process. That bit about the ability to "twist" the lines into alignment is a good point too - the longer the better. I knew there was a reason why I liked having you around here.
What about the added volume of fluid that has to be moved with 2 large lines? Any thoughts on that? I thought no real effect but then exaggerated the lengths as a thought experiment, say to 10' each. Would that effect the feel at the lever? The culprit would be lack of efficiency/loss due to blow-by at the master cylinders piston. Cars have much greater length of line and hoses but they also a larger master piston. Maybe I'm over-thinking things. Again.
With virtually uncompressible liquids like brake fluid the losses from increased length are friction only. Negligible even with fairly long lengths if they are well bled.
Are you going to switch to DOT 5.1?
I haven't gotten that far yet. I haven't even begun looking for a 5/8" master cylinder yet. The 11 mm currently installed and the stock RJ 1/2" would be way to much. Is DOT 5.1 what all the kids are using now? If so, I'll want to keep up with the times.
It wasn't compressibility I was worried about but rather the inherent inefficiencies of the master i.e. internal leaking past the cup. I'm sure I was over thinking it. It's already been done successfully so no need to reinvent the wheel.
All the 16Rs have twin rotors. I've never had an issue with brake blow-by. Don't stress about it.
Here's a source for what you need:
https://yambits.co.uk/xz550-brake-master-cylinder-p-103045.html (https://yambits.co.uk/xz550-brake-master-cylinder-p-103045.html)
Wow, that's a nice looking pattern part. That's $65 in US greenbacks plus shipping. I think I can do better but I'll keep them in mind as a contingency plan.
The XJ Yamahas had a single line to a distribution block (manifold) on the lower triple clamp. Works a treat. Equal length lines to each side with one from the master. No twist. No routing problems.
https://www.ebay.com/itm/Yamaha-XJ-650-4K0-Bj-1980-Brake-line-distributor-N1795/402124035720?hash=item5da075d688:g:bm8AAOSwT-NeV6MR