Making it drive better

[jetmechmarty]

My stock SK that I've had since new was overdue a fork oil change. I redid my XS1100 with new straight rate springs and Gold Valve emulators a few years ago and I'm still thrilled with it. By comparison, my XS650 front suspension sucks, and sucks bad.

I replaced the oil this evening. I put the recommended amount of oil in the right fork and put the cap on it. I bounced it and realized it's still going to be awful. I took the cap back off, removed the spring, collapsed the fork, and added oil until it was 130 mm from the top. I put the cap back on. I did the other one the same way. This thing is going to rock my world. Before I even get the bike back together, I can tell the improvement is going to be huge. My XS1100 is filled the same way as recommended by Race-Tech.

This thing should ride like a new bike at the Dogwood Rally next weekend. I expect the braking and corner carving will be vastly improved. No more terrible fork dive! The best part is it only cost a quart of fork oil!

 

[angus67]

Yup. Even though the oil isn't subject to heat, it still breaks down.. So is that a oz more?. I went a oz over as 5twins recomended on my 1980 forks, and with no mods, work great

 

[5twins]

I discovered more oil is better in these forks the first time I changed mine. With a fresh load of the stock amount, you could actually hear it sloshing around in there when you pumped the forks up and down in the driveway. I added more, going with about 7 ounces per leg instead of the spec of just under 6. It made a very big difference, for the better. I don't think I've got quite as much in there as you went with but the bottom line here is these forks just plain work better with more than the stock amount of oil in them.

 

[jetmechmarty]

Yes. My poor forks were neglected. The fluid was probably more like abrasive than lube.

It looks like there's a pint left in the bottle. I used the Race-Tech spec to fill them. With springs out and forks collapsed, I left 130 mm of air space on top of the oil.

I may start riding this thing again! I hope to see a few of you at the Dogwood Rally next weekend!

 

[XSLeo]

130 mm is about 5 1/8 inch down. I fill mine to 6 inches down, or 152 mm. Works very well.
Experimenting with different weight oils or different amounts isn't expensive but you may find a better set up.
Leo

 

[jetmechmarty]

Use 15w (US3) Fork Oil set to 130mm Oil Level (Fork Spring out, chrome tube at the bottom of stroke) Oil Level Tuning Range is 110-150mm in general.

The above is from the Race-Tech Tuning Guide. Leo, you're just about in there, so you already figured out the formula. I use 10w. The 15w recommendation is for emulators which means the damper rods no longer function. I don't wish to slow down compression damping, so I choose to stick with 10w. My emulator bike has 15w. YMMV.

I think this is going to make me happy. It's easy from this point to add or remove a little bit of oil. Yamaha got it wrong when they wrote the book, or I missed what they were going for.

 

[angus67]

Yamaha went for squishy. You know....Cadillac ride.

 

[5twins]

You might consider the Minton Mods too. They really help smooth the ride out over the little stuff. Makes normal day to day driving much nicer.

 

[jetmechmarty]

You might consider the Minton Mods too. They really help smooth the ride out over the little stuff. Makes normal day to day driving much nicer.

The roads here are silky smooth for the most part, and very crooked. What I just did makes the bike a far better ride than it was. The dive in the front was horrible. I went the emulator/spring route on the big XS and it's quite a transformation. It's no R1, but not its old self either. What I did today cost virtually nothing. The makeover can get up to and over $500 depending upon whether you do the work yourself and how much the screw-ups cost. I had put the Minton mods into the old school we don't do that any more box. Perhaps I'll take another look.

Here's the old girl after her post maintenance shake down. It's a stock SK wearing SH wheels.

 

[angus67]

Whether or not we dont do that anymore, its not like these bikes parts have changed. Stock 1980 forks will always be 1980 forks.

 

[5twins]

I don't understand why Minton's fork mods are being treated that way. I can see some of the other things in his write-up being pushed aside, shelved so to speak, because many of the vendors he mentioned are gone, but I see nothing wrong with the fork stuff. It's pretty much like the extra oil you added, virtually free. It also doesn't stop you from going to emulators in the future if you choose to. You simply drill the dampers again with even bigger holes, that's all. And what I think is most important is that they actually do something, they help the forks.

Minton notes in his article that the 650 forks are slow to respond to little bumps and that first initial bump you hit. I found that to be spot on when they were stock. The little stuff feeds right on up through and jolts you through the bars instead of being absorbed by the forks. Drilling the damper rod holes slightly larger remedies this problem.

I can see shelving Minton's fork mods the way they're written. They don't make complete sense because what he describes (number and size of holes) isn't what you'll find on your damper rods. But I've sorted all this, at least to my satisfaction, and feel they work pretty well. I was leary myself about trying them so I did them to a spare set of damper rods. They worked so well, I don't bother with spares anymore, I just do them.

 

[jetmechmarty]

Yep. I get it. The best part of the Minton mods are that they're free. They've been around a long time, and no one has ever said "Don't do it. It will ruin your bike!"

I've had it in my head that someday I was going to rework the forks. A lot of somedays have come and gone and I never even deviated from factory setting on oil level. So now here it is, 33 years later and I've finally done something to make an improvement.

 

[azman857]

What Timeing! I am going to change the oil and fork seals and do the Minton mods soon.