Wanted: Suggestions for GS650GL chassis refresh/mods

[buddha]

Hello all,

I've been considering how to refresh my suspension since I purchased my GS650GL one year ago. Motor, fluids, tires, brakes, etc... have all been sorted out, so the 2nd-to-last work remaining is the suspension. The front forks are gently seeping, but the damping is almost nil. The rear shocks are basically toast, including the fact that my jounce bumpers have completely disintegrated (ask me how I know). I'm fairly confident that I will keep the original forks (for now) and upgrade them with Progressive springs and some fresh oil and seals. I'm having a harder time with the rear though. Let me explain why.

First off, I'm not fond of the GL's profile and handling characteristics, so I'm not interested in keeping it exactly as it came from the factory. I haven't decided which direction I'm going to go with the bike (rat, cafe, custom), but I'm definitely not keeping the "laid back" look. I've already changed the bars out to something more conventional (superbike style) and I like the way that improved the feel. I'm sure the tank, seat, and tail will follow at a later time.

I wanted to fiddle around with the trail a little bit to see if I could improve the turn-in feel without making it unstable. The stock GL chassis geometry makes it turn in a little slow for my taste, and I'm sure the 19" front wheel doesn't help. For sh*ts and giggles, I tried raising the front fork tubes in the triples to see what the effects would be. Turns out that 15mm makes a huge difference to the feeling of the bike during corners. Of course, I had to go back to original after I found it was easy to bottom the forks in tight corners.

Then I had the great idea of getting longer rear shocks to accomplish the same result. Raising the rear of the bike should accomplish the same trail reduction without causing a suspension travel issue that I had with the raised fork tubes. Currently I have 12.5" rear shocks. I know that the GS650G uses a 13.5" shock, so that would be an easy swap. I'm sure there are other possibilities as well.

I've been looking closely at the Progressive 412 series for the GS650G (Part #412-4216C), but I'm little hesitant on the price. This is my first motorcycle and it's probably not going to be my last, but it's what I'm enjoying now. I'm just hesitant to blow ~$300 on rear shocks. I know it will make a huge improvement to the bike's handling, but it still seems like overkill. After searching online, it seems that the next grade level below Progressive seems to be EMGO/MDI, and I haven't heard many good reviews about their shocks.

Now the questions:

1. Does anyone know if there are any negative side-effects caused by raising the rear to improve turn-in (decrease trail) with longer rear shocks?

2. Do you have any other suggestions about how to modify the suspension of my GS650GL? Yeah, I'd love to have the time to go "mono-shock", but that mod is just not realistic at this time. I'm just looking for ideas within the realm of my budget.

3. Do you have any other rear shock suggestions? Reasonably close take-offs? Other alternatives? I'm trying to stay away from the EMGO/MDI type replacements, as I tend to hear that they are not so good, but there doesn't seem to be any other brands in the $100~200 range.

4. Has anyone tried using a GS650G fork on a GS650GL? How was the result? Any idea how easy it is to use the GS650G upper parts (tank, seat, tail) on a GS650GL frame?

5. Does anyone have any info about the frame differences in the GS650 line-up? I know most of the differences in the 650's is in the bodywork, forks, and rear shock height. I just don't know how much geometrical difference there is in the frames.

I'm open to any thoughts you might have.

Thanks!!!

[buddha]

Someone must have tinkered with their GL's chassis? I can't be the only one?

[nisom512]

Hello all,

2. Do you have any other suggestions about how to modify the suspension of my GS650GL? Yeah, I'd love to have the time to go "mono-shock", but that mod is just not realistic at this time. I'm just looking for ideas within the realm of my budget.


Thanks!!!

Mono is really not that great of a mod not much benefit from what i've heard.
Oh and normally different seats from same bike but different model dont fit from what i've gathered

Someone must have tinkered with their GL's chassis? I can't be the only one?

Yes people have just give them time. this performance sub-forum is not visited as often as the technical

[mpls-ugly]

Just chiming in to say im interested in tis subject also. I have a 650 Gl and the front forks are just too long for my liking. Im dont know if its the ride or the look but all in all i hate it. My solution was to chop 1" of my fork springs. I don't think I did a very good job because I probably lost 1 1/2 inches after heating them up and squishing them down so they lay flat against the caps as intended. I had my bike on a stand all winter and now that its on the ground I think i went too far. I still need to mount my exhaust and ride it to see what my clearance is but I think I will be buying new progressive spring for the forks. or going the direction of a swap. This is my firs bike so I have encountered a couple costly mistakes. Steep learning curve. hope you get some help on this.

[nity11us]

see this post by MRNessism

http://www.thegsresources.com/_forum/showthread.php?t=134733&highlight=lowering

--al

[trippivot]

new fork seals
new progressive springs
15 weight FORK OIL

NEW progressive rear shocks-they will swap springs if you need stiffer or softer FOR FREE.

nice set of matching tires maybe a chain and sprockets set.

leave the rest alone. forget used crap. don't cut and weld unless you have a frame jig.
#1 reason modified bikes get sold is they are crooked and dog track
just ask the mono shock/ raked out guys how many times it took to get it right

and hope they tell you the truth.

[buddha]

Nice! All good F/B. I will be ordering the parts for the forks sometime this week. I'd like to at least get that bit of wrenching out of the way while the morning temps are creeping above 60'F.

Responding to Nessism, I'm aware of the trail effects when installing the center axle forks. I'm assuming that the combination of raised rear and centered fork axle balances out the changes in trail. If you check the spec differences between the G and the GL, the trail is not that much different. Actually, the GL already has less trail than the G (109mm vs 113mm) already.

I think that the combination of the centered axle, longer rear shocks, and slightly different caster angle help contribute to the change. One would expect that the handling characteristics of the G should be a little quicker/sharper than the GL. Therefore, I think it would be safe to assume that the flavor of the G handling is influenced by more than the just the trail (meaning rear height, squat characteristics, caster, etc....).

I guess I'm worried that raising the rear of the GL without changing to the centered front axle will over-reduce the trail making the bike a twitchy mess. I guess the best way to figure it out would be to try it. This is another reason that I'm curious about the frame differences between the two models. I might be missing some simple difference that balances everything out.

[buddha]

Trippivot...I'm with you on the cut/chop jobs. I'd like to keep my frame intact for now and modify without chopping. I'm thinking I can get the look I want without any cutting. At least that's the plan.

[buddha]

Hmmm.... How to decide between Hagon and Progressive?

[nefarious3d]

I've got a 1983 gs650gl as well and I'm in the process of a complete tear down/refresh. To my knowledge, the front-end off a 1989-92 gsx-r750 should mount right up. I just ordered one though, so I'll post a few pictures when it arrives and detail any complications.

Cheers.

[Wraith]

GSXR front ends go on, from the early G/H/J up to the 750WN USDs. Check first though as though they're all shorter forks than standard GS, some of them might be too short, especially I think the latter models, so possibly best not going past the GSXR1100M.
A mate of mine had a front end off a ZXR400 on his GS550: had to change the GS's steering stem (push out original and swap for ZXR one and I think make up a sleeve as ZXR stem is thicker) and put new lock stops on, but not a big job.
I've got a ZXR750J2 front end on my GS1000G, with an NTV650 single-sider shaft on.
You can put the Suzuki VX800 rear wheel in the standard GS swing arm to get a 160 rear tyre.