1979 GS425E Suspension, Brakes Setup

[Guest]

Hi,

I've got a '79 GS425E that I'm getting back on the road. I've already test-ridden it, things went well. Two things left I'd like to deal with.

1) Suspension setup. I don't know how to set up a motorcycle suspension properly; I've always just left things the way they were when I got them. I'm 6', 180 with gear. The bike is a little small for me but it's responsive and nimble, and I like it.

-My front forks are raised about an inch in the the triple clamps. I assume I can put them back down and gain some height? No reason for them to be there, right?

-I get a LOT of brake dive. What are my options to limit this?

-My rear shocks are set on the lightest setting. I don't know where I should be for them?

-I don't know if there is any adjustment at all in the front fork besides the fluid viscosity?


2) Brakes.

-The front brakes are bled with new fluid and EBC pads that have a couple thousand miles on them. I get nothing really special in the way of stopping power; the EBC's and the stock brake pads are very similar. You really have to bear down on them to get a good stop, it's a whole-hand operation and not a 2-finger like on my modern bikes. That coupled with the brake dive makes stopping a little more interesting than it should be. Is there any way to improve this?

-Rear brakes are adjusted and work fine. I don't use the rear though unless it's an emergency.


Thanks for any help / suggestions. I'm up for whatever, including swapping front forks to something more modern if that'll help. I really like the rest of the bike...but the front end is showing it's age.

[tom203]

Drop the forks down.....put rear shocks on harder setting. But both ends might be tired.. easy to opt for new rear shocks, but front upgrade is more challenging
you need to rebuild your brakes..master cylinders and calipers....both ends....your life depends on it. Changing fluids and pads ain’t enough.
there are plenty of threads on how to do this in this forum

[JBI]

I rebuilt the front brakes a couple of years ago, master cylinder and caliper. I'm thinking the line could be swelling and I might be losing some pressure that way. Looking at SS lines right now.

Rear brake is a mechanical drum. Nothing to rebuild, and there's nothing wrong with it.

[Nessism]

Be sure to do basic maintenance like valve adjustment.

The 425 is a nice bike. Roller bearing crank unlike the 450.

[Suzuki Mad]

Top of the tube should be level with the top of the top yoke (triple tree where you are.) Might be worth stripping the front end down, check spring length and change the oil from original (10W) to something a little stiffer.

Rear has a 5 position adjuster at the bottom of the unit. You lift it to a harder setting as somebody has already suggested. It's possible it very tired as a shock so new ones may be needed. (Hagon do a good shock here in the UK.)

I never found an issue with my 425 stopping but that was in 1980 when I had one new.

If you need a handful to stop it then maybe its time to check the master cylinder, change the brake fluid (every 2 years) and are you using the original brake hoses? They might need replacing now.

[JBI]

Thanks everyone for your help and interest so far!

Valve adjustment is still a thing to do, plus I've got an oil leak starting between the head and the jug. I'm going to do both of those things this coming winter. The bike has 8900 miles on it.

Just got done doing a *bunch* of work to it, about all I want to deal with for the moment. Basically what I'm doing now is researching the next group of work I'll be doing this fall / winter, except for the quick stuff which I'll take care of now. And the important stuff, which at this point is the brake line at minimum.

The bike is in pretty good shape, and after adjusting the needle heights to full up, it moves right along like it should have from the factory. I have as much fun riding this machine as I do much newer and more powerful ones.

[Nessism]

Some stiffer fork springs would help.

There is a very good chance the valves have never been adjusted and that means they will soon start to hang open and could burn. You would be wise to check them now and not wait until it's too late.

[Gorminrider]

I've got a couple of 81 400's and I like them a lot....I haven't been bothered much by it but complaints about brake dive when front brake was seriously applied were common in reviews per the 450s and the 425/400 iteration. There's some good advice above to try.. Obviously, levelling the forks down through the trees will lift you up a bit and reduce the angle of the dive!. An extra short spring or just a short piece of pipe forced in on top can serve to "preload" the springs similar to what you can do so easily in the rear....15w oil might slow the dive down...but all these will affect the ride too. You're about max weight as a single rider for this bike I think so stiffening the suspension judiciously would likely suit you. My 400E has straight wound springs on the rear shocks and even being lighter than you, they need one notch.

By the way, shocks actually warm up and get better after riding awhile. Mine do,anyways but they are ALL "originals" and very old. They come apart. so dampers can at least be checked for proper operation even if they can't be rebuilt.

Check the level of the fork oil too. It controls the compressible air space in the fork but don't add a lot of extra oil or you'll restrict the motion altogether and build up airpressure quickly....

The front brake on mine is pretty good and don't need a lot of grunt couple of fingers does it. But I'm lighter than you. Still, assuming it is the same brake as yours ( I haven't checked the partsfiche) and apart from all the good advice above (though I'm still using the original brake line on one of mine) you can try a simpler thing first: clean the disc with alcohol/methyl hydrate or even just water and detergent well-rinsed to remove any oil and dirt. Then Take the pads out and give them a rub with 100grit sandpaper wrapped on a flat stick to remove any glaze...you can do the same on the rear of course. If the rear gets to squealing, sanding the sharp leading toe of the pad off will fix it for awhile....

[JBI]

Hey, thanks a lot to everybody who's helping me out here. Is there a spec for how much sag I should be getting at the front and rear when I sit on the bike?

[Gorminrider]

Not really any "specification" but there's a ton of stuff online about it...I've read a lot of them but my conclusion mightn't be the same as yours...It has a lot to do with how and where you ride and WhatYouWantToSpend too.