SR500 Minton mods

nighthog

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Hi all, about a month ago I bought a 1980 SR500H stablemate for my 1982 XS650SJ. When I got the XS ready for the road, having purchased it in an unrideable state, I did the Minton mods on the forks as per this article and I've been very pleased, the combination of that and new Hagon adjustable rear shocks works well for me.

The SR500 has awful suspension. The cheap, rock hard aftermarket shocks will make way for Hagons at some point and I have All Balls taper head bearings in the post, but my question for you suspension gurus is about Minton mods for the forks, which are very similar to the XS forks. I figured I could just repeat what I did on the XS but I'm not so sure ... The SR minton mods describe the forks as 'Under-sprung, under-damped, lots of seal friction and some flexing' while the XS version says 'too much rebound dampening' and 'also has too much compression damping'. Somewhat contradictory.
I have Hagon progressive springs coming and plan to fill the stanchions to 6" from the top with 10W fork oil and maybe raise them 1cm through the yokes, but damper rod mods as per the XS? Hmmmmm ..... my feeling is to leave well alone at least for now.

I know that a number of other members also have SR500s; do you have any advice?

Oh yes, here's the obligatory pic!
20210411_173322.jpg

Cliff
 
under-damped,
The main cause of under dampening is passing fluid too readily during compression and/or rebound. Making the holes bigger (al la Joe Minton) will only aggravate that. Your best bet's gonna be trying progressively thicker weights of oil until you get acceptable dampening.
 
Thanks, fellas. Minton's logic for the XS was along the lines of 'pass more fluid but make it thicker fluid' and all I can say is that it works. Think I'll stick to my plan of not modifying the damper rods on the SR though.
 
What I did for the Minton mod with my XS Cliff, is drill two extra holes in the valve body to equal the hole area Joe went for. I did that with an eye toward being able to TIG them back closed and back to stock if I didn't like the mod. Have a read here. If you do decide to give it a try, you might consider that.
 
The SR forks are the same as the 650 forks except for the softer springs (probably because the SR is lighter). I'm not sure why Minton didn't recommend the damper rod mods for the SR, and I don't see why they wouldn't help. On my SR, I think the only change I made was installing the Progressive springs. But before I did that, I put 1" longer preload spacers in with the stock springs. I seem to recall Minton suggesting that in one of his SR articles. But he said the stock springs would continue to weaken over time so that longer spacer was sort of a temporary fix. But I have to admit, I liked the forks like that, better than after I put the Progressive springs in. They were harsher. I'm thinking some stock 650 springs might work well in the 500 forks. Do you still have the ones from your 650?

I did install a fork brace on the SR but took it off after a couple years because I found it did nothing. The bike is so small and light, it didn't need it. Eventually, that brace went on my 650 and on that bike it did help.
 
Well, when I measured the springs on the XS they were well within tolerance so they went back in. I could only squeeze in 1/2" of spacers (I used 22mm washers, which was all I had available) but hey, that seems to work.
I can't weld, but I have a friend who can, but I think I'll try without the extra holes to begin with. I can always drill them later.
Any change can only be an improvement - a ride down a local country lane knocked the wind out of me and almost kicked me out of the seat!
Thanks again, chaps :)
 
My 650 replaced my SR as my "around town" bike and the SR has been off the road in storage ever since. If I do bring it back out, I'll be making some changes, some based on what I've learned with the 650. First up would be gearing. When I was riding it, I had upped the front sprocket one tooth to gear it up. From gearing changes on the 650, I've come to realize I had geared the SR too high. It wouldn't pull red line in 5th and wouldn't go much over 80mph, but I'm a big guy (6', about 210 lbs). My light weight buddy hopped on it and ran it right up to near 100 no problem. He told me I'm too big for it, lol, and I think with that gearing, I was. So, I would go back to the stock front sprocket and down-size the rear a couple teeth instead. That would gear it up but not as much as one up on the front did.

I have extra damper rods so I'd try some Minton modded ones, and extra stock 650 springs, also extra 3-way adjustable preload caps. I'd also like to do a spoke wheel conversion. I acquired an XT500 rear wheel several years back so it's just a matter of lacing it up to a suitable rim. A 650 front wheel is a direct swap and I have several of them.
 
Until the parts arrive and I have the time & space to have a go at the front, I'll try the old XS shocks on the rear. I took the springs off yesterday and can see that the damping works, so I'll clean them up, put them back together and try them on the SR. Cheaper than buying new Hagons! 5T, I'm about 155lb and the current shocks seem rated for someone twice my weight.
Regarding the forks, Jim - your link, that's exactly what I did to my XS. Where my doubts came in is in the contradictory nature of Minton's comments. His SR article was about 5 years later than his XS one so you'd think that the later one would be on the basis of greater experience. So why not the same recommendation? My thinking at the moment is:
1. fit the progressive springs, fill to 6" of the top with 10W, drop through yokes by 1cm (sit up & beg bars tend to take weight off the front so this will help a bit)
2. if the front's too hard after that, open up the holes in the damper rod

If it all goes horribly wrong, I'll bribe my welder friend with beer :)
 
The SR500 has awful suspension. The cheap, rock hard aftermarket shocks will make way for Hagons at some point and I have All Balls taper head bearings in the post, but my question for you suspension gurus is about Minton mods for the forks, which are very similar to the XS forks. I figured I could just repeat what I did on the XS but I'm not so sure ... The SR minton mods describe the forks as 'Under-sprung, under-damped, lots of seal friction and some flexing' while the XS version says 'too much rebound dampening' and 'also has too much compression damping'. Somewhat contradictory.
I have Hagon progressive springs coming and plan to fill the stanchions to 6" from the top with 10W fork oil and maybe raise them 1cm through the yokes, but damper rod mods as per the XS? Hmmmmm ..... my feeling is to leave well alone at least for now.

I know that a number of other members also have SR500s; do you have any advice?

You could do a lot worse that fit Racetech Gold Emulators which with the springs and the static sag set will transform the performance of conventional forks.
It they can tame the front end of my V Max the an SR shouldn't present too much of a problem?
 
Until the parts arrive and I have the time & space to have a go at the front, I'll try the old XS shocks on the rear. I took the springs off yesterday and can see that the damping works, so I'll clean them up, put them back together and try them on the SR. Cheaper than buying new Hagons! 5T, I'm about 155lb and the current shocks seem rated for someone twice my weight.
Regarding the forks, Jim - your link, that's exactly what I did to my XS. Where my doubts came in is in the contradictory nature of Minton's comments. His SR article was about 5 years later than his XS one so you'd think that the later one would be on the basis of greater experience. So why not the same recommendation? My thinking at the moment is:
1. fit the progressive springs, fill to 6" of the top with 10W, drop through yokes by 1cm (sit up & beg bars tend to take weight off the front so this will help a bit)
2. if the front's too hard after that, open up the holes in the damper rod

If it all goes horribly wrong, I'll bribe my welder friend with beer :)


Contrary to popular belief... good tradesmen don’t like working for luke warm craft beer treat em nice
 
Chaps, I'm returning to this as I had to break the forks down to replace leaking seals and ended up also replacing one upper bush and these ruined stanchions
20230502_151145.jpg

While I had it all in bits I thought I'd make a further improvement - the Hagon progressive springs + 10W oil improved the spriinging no end, but the damping was still crap. I've been very pleased with the Race Tech springs & emulators I put in the XS, but I don't use the SR anywhere near as hard and want to keep cost down, so bought some YSS emulators. Those, 15W oil (guesswork) have given me a very (a bit too) firm front end but little travel. The extra 14mm of preload from adding the emulators has oversprung it, and I think I'll return to 10W oil to soften it a bit.

There was 35mm of preload before adding the emulators, so that's now 49mm, and clearly too much.

The Hagon springs are 5mm shorter than the SR original setup, while the XS springs from my '82 are shorter. Here's Hagon and standard, then original and XS:

20230430_123425.jpg 20230602_100426.jpg

I don't want to cut down the Hagon springs and I figure I can use the XS ones (well within tolerance) with suitable spacers to get the right preload. To get a starting point though I would like to know what the preload is for late model XS forks? People sometimes mention 'no preload' when what they mean is no additional preload and I can find nothing in any spec or from searching this site. There is much discussion about adding preload but nobody states what it is to start with.

The SR is a lighter bike so probably will be OK with 'standard' preload - can anbody enlighten me as to what it is?

Thanks - Cliff
 
My XS1100 has RaceTech emulators in it. It also has custom wound springs. I made my spacers so that when my fork components are all in place, the top of the spring is about even with the top of the fork tube. I really have to push to get the top caps on. That’s it for preload.

I originally set the bike up for North Georgia mountain roads with pavement as smooth as glass. Riding on the 3rd world roads of Mississippi was awful. I removed the emulators and turned the adjustment one full turn out and reassembled. Fixed! It soaks up bumps just fine. That’s the beauty of emulators.

I hope you’re using straight rate springs. Trying to tune emulators with progressive springs could prove impossible.
 
1685715331608.png

I can not tell for sure, but it looks like your Hagon spring is progressive wound. If so, it's never going to get along with emulators. Straight rate springs are required as emulators and progressive springs are competing technologies. Progressive springs and damper rods are old school. Valving is the new way.

Also, you have to ruin the damper rods to runs emulators. They can not restrict flow at all. They need more and bigger holes. I don't know if YSS provided these instructions or not.
 
Yes, I know I should use straight rate springs but I'm trying to keep the cost down by using what I've already got as much as possible. The Hagons are progressive, as are the XS and SR ones so I figure that while whatever I can put together won't be ideal, it should at least be an improvement over the standard damper rod setup.

If all fails, I'll stump up for Race Tech springs. Not near that point yet though!
 
If all fails, I'll stump up for Race Tech springs. Not near that point yet though!
You are not required to source your springs from RaceTech. I'd be very surprised if you can't get springs in the UK, or at least in Europe. My XS1100 does not have RaceTech springs. I bought them locally and to me, they're perfect. My bike has straight rate and emulators up front and Progressive Suspension shocks on the back. It works very well, especially as compared to my stock suspension XS650 bikes.
I have to say it again. Progressive springs with emulators is not going to work. I've had friends try it. I've ridden an XS650 set up that way. It's worse than stock. You can't tune it. It has been some years since I bought custom springs, but I believe they were $130. I guess it won't cost you anything to try it and I don't believe is dangerous, so have a go.
 
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