Front suspension mods

Gmaan · Posted: December 9, 2007, 3:29 am Post subject: Front suspension mods

What is the deal with "drilling" out the front fork dampeners? How do you modify the front forks to get better handling. I am rebuilding a set of 1980 forks to put on my bike, and have heard about drilling out the dampener tubes. What is the scoop on this?

BiffTirkle · Posted: December 9, 2007, 11:26 am Post subject: Re: Front suspension mods

ive met people who have drilled the dampers, but ive also heard people say that is the dumbest thing to do to your forks. i personally havent done that mod. mikesxs sells a damper valve set that is supposed to do the same thing as drilling your forks. 650 central has a set too. check them out.

www.mikesxs.net/mikesx...ory_id=6.2

www.650central.com/

xsjohn · Posted: December 9, 2007, 11:55 am Post subject: Re: Front suspension mods

Drilled mine out.......now I have to find some more dampners....total mess.....dumbest thing I have done so far.......and worse than that I don't think there was any thing wrong with them that the correct oil would have solved......Maybe the right oil mix would have been much easier than having to take the whole stinking thing apart again......and even worse than the trashed dampners is that the original seals never leaked any......I changed them to new seals and they leak like hell....just shoot me......If I ever sell a fork kit don't buy it........

John

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

The damper rod mods come from the old "Minton Mods" article. You can read it here .....

www.650central.com/tec...onmods.htm

I went to do the ones on my '78 and found the factory had already added the 2 extra large holes at the bottom of the rod (for a total of 4). I didn't bother with adding the 2nd small one at the top. I was just bringing the bike out so figured I'd try the forks first and see how they were. I set everything up stock. Stock weight and amount of oil, stock springs, etc. It quickly became evident that my original springs were worn out.

I installed Mike's progressive springs (cheaper than the real PS springs) and, while I had it apart, I checked the oil level with the stock amount. Springs out, forks compressed, the level was nearly 9 1/2" down, way too low I thought. It actually felt that way when it was still assembled. Pumping the forks produced a squishy sound like there was more air than oil in there. A common mod for many bikes is to set your oil level at 6" from the tube tops. Minton even recommends this in his article. I added an additional ounce to each leg. Stock amount is just under 6 oz. per leg and I'm running about 7. This brought the level up to near 7" from the tube tops. With the new springs and additional oil, I'm very happy with my forks now.

So my recommendations would be new progressive springs and 7 oz. of 10wt. per leg. I would examine your damper rods to insure they have the 4 large holes at the bottom (they should since they're newer than mine) and if not, I'd add them.

Tomterrific · Posted: December 9, 2007, 2:48 pm Post subject: Re: Front suspension mods

Hi John,

i would try one of two things to get those forks acceptable. One is simply fill the legs with straight 30w. The thick oil will compenste for those big holes and the thick oil won't leak as much and lubricate the sliders better.

The other is a slam-dunk. Spend the $49 on the Cartridge Emulators mikesxs is selling. What a deal! These have an adjustable valve that holds to keep the forks stiff until you hit a sharp bump like a 2x4, then the valve lifts and the forks react fast. The forks have both high damping and low damping depending on conditions. The damping holes need drilled out so you all ready are half way there.

Tom Graham

xsjohn · Posted: December 9, 2007, 4:44 pm Post subject: Re: Front suspension mods

Might be able to save mine by closing the top hole a bit...may have over done it .....I have 60-80 weight oil in them now and still bangs when it extends......the seals I have no idea why they leak....I have replaced hundreds without leaks and now it just pours out..may not even be any oil in them now.....I am sure that can be fixed with decent seals......If that doesn't work I will try mikesxs.....

John

Gmaan · Posted: December 10, 2007, 3:47 pm Post subject: Re: Front suspension mods

Well then, new springs and more oil is the answer. I have the forks torn down, and finished polising the tubes yesterday. Next weekend I will have the front end together with new springs, seals, dust boots, and tappered head bearings.

Pics to come

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

You might consider fork gaiters instead of the dust shields. They protect the seals much better and have that cool retro look.

album.650wiki.org/view...rk_Gaiters

bluebikerblan · Posted: December 10, 2007, 8:44 pm Post subject: Re: Front suspension mods

I agree with the "Gators" suggestion. Have now done 3 sets on three 650 redo's this year. Like the ones from MMM at 650 Central best. They fit the fork tube and the shock body without fitting a piece of radiator hose or some such on the tube Appear a little more heavy duty as well. Nothing like clean sliding.

Retiredgentleman · Posted: December 11, 2007, 2:37 am Post subject: Re: Front suspension mods

xsjohn; for sure on the fork seals...............I went to the trouble to replace the fork seals (from mikesxs) and they leak like a sieve. Has anyone put in fork seals from mikesxs and been leak free? Can anyone recommend a better seal?

xsjohn · Posted: December 11, 2007, 10:03 am Post subject: Re: Front suspension mods

Roy reccomended parts ulimited fork seal FS011....that was a year ago...maybe he can add more to this delima now......I was so bummed about the leak I have just been adding oil to mine....but eventually the caps will give out.....at least the fork tubes won't rust.....seems the seals are touching in some places and have gaps in others......this time I am at a loss......like I said before I am really pissed at myself cause they didn't leak any before the repair.....duh.....and the dampening was good for me....not now.....

bought the replacements from a guy on ebay who claimed to have sold hundreds without any leak problems....when I contacted him he called me an idiot and should contact professional help and quit shade treeing...maybe he is right......

After thought....the original seals must have been a tighter fit on the fork tube......only explaination I can think of......or the guy on ebay was right...

John

grizld1 · Posted: December 11, 2007, 4:49 pm Post subject: Re: Front suspension mods

If you're serious about handling, cartridge emulators (damper valves) are the way to go. I've used Race-Tech emulators for years; haven't seen Mike's units, but if they're good the price is a bargain. Damper rods must be drilled for the emulators, but not to the Minton specs. There's nothing wrong with Mike's seals; they're from the OEM maker. If the fork tubes show any evidence of pitting at all in the swept area they'll cut the seals. I've managed to smooth off tubes with minor pitting by setting them upside down so that any runs or sags move away from the swept area, hitting the pitted area with rust bonding spray paint, and levelling off with 1500 grit paper. It's ugly (rust inhibitor cures black in the pits), but it works just often enough to be worth a try.

MaxM · Posted: December 11, 2007, 5:20 pm Post subject: Re: Front suspension mods

Have to agree with grizld1, Racetech emulators & springs + setting the static sag correctly will transform the front end.

Come to think of it, just setting the static sag will probably be a major improvement!

grizld1 · Posted: December 12, 2007, 12:41 am Post subject: Re: Front suspension mods

Yep, gotta set sag, front and rear, both static and laden, if you want good results. Emulators work best with straight rate springs, and springs with correct rate for bike and rider weights are very important. There aren't any off-the-shelf straight rate springs available for XS650 forks, either 34 mm. or 35 mm., but Traxxion Dynamics at www.traxxion.com supplies custom springs for a very reasonable buck. The suspension's a system; you can't just bolt stuff on and get trick handling. I wouldn't throw money at trying to improve the performance of the 34's.

Tomterrific · Posted: December 12, 2007, 11:17 am Post subject: Re: Front suspension mods

Loctite makes this stuff they call Liquid Metal. It is a liquid (duh) that sets up to take the place of worn metal. I think it hardens silver. My thought is to take the badly pitted legs and clean the rust and oil from the pits, fill the pits with the Liquid Metal and smooth the L. Metal level after it sets. A gaiter is a great way to finish off any conventional fork. Protective and looks oh so right on an old bike.

Tom Graham

bluebikerblan · Posted: December 12, 2007, 5:22 pm Post subject: Re: Front suspension mods

Retiredgentleman wrote:

xsjohn; for sure on the fork seals...............I went to the trouble to replace the fork seals (from mikesxs) and they leak like a sieve. Has anyone put in fork seals from mikesxs and been leak free? Can anyone recommend a better seal?

I wouldn't presume to make direct comparison but I was very pleased with the non-leaking results using the All Balls & Bearings triple lip fork seals I got from 650 Central. Ditto with their tapered stteering column bearings.

xsjohn · Posted: December 12, 2007, 5:47 pm Post subject: Re: Front suspension mods

Might try them....there was no good reason my replacements leaked.....tubes have no marks or pits in them.......

John

jayel · Posted: December 12, 2007, 11:22 pm Post subject: Re: Front suspension mods

heck I just went to the local auto supply store, told them what size I wanted they ordered them and no problem

xsjohn · Posted: December 12, 2007, 11:42 pm Post subject: Re: Front suspension mods

Jayel...Some people have all the luck...nothing like a big leak to deflate my ego......and my time....oh well just do it again I guess....enough times then luck would have to work in my favor.........

John

Retiredgentleman · Posted: December 13, 2007, 2:42 am Post subject: Re: Front suspension mods

I think I may order fork seals from one of the recommended sites.............thanks for the info guys. Getting tired of wiping off the oil around the forks after every ride. This long canadian winter gives lots of time for repairs..............back wheel is off for new tire and brake rotor drilling............new pads as well.

grizld1 · Posted: December 24, 2007, 12:14 am Post subject: Re: Front suspension mods

Retiredgent, sorry, I missed your question on whether anyone had had good results with Mike's fork seals. I've redone several front ends with them and never had a problem. I did the front end on my own XS650 about 6500 miles ago, and the seals are holding nicely. One important step that's often missed is using a good grade of grease on the outer surface of the seal in installation. Race-Tech seal grease is pricy but excellent. Be sure to lube the inner seal surface and fork tube with fork oil, too.

Something to bear in mind is that as fork tubes rack up miles they become slightly sway-backed. This condition can become bad enough to cause premature seal wear. Check 'em by rolling on a piece of plate glass or other known-flat surface and checking the gap between the tube and the surface with a feeler gauge.

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