GS850GN Front Forks

[Guest]

After doing an almost complete rebuild/semi-restoration from a bitsa chop with 1979 850 engine/swingarm to something that actually is a majority of a GS850GN, it's almost done (running, stopping, taxed, MoT'd, insured, but sorting a few niggles).
The biggest issue at the moment is the centre stand - mainly i can't lift the bike the 4 inches required to get it onto the stand.
Having broke the stand (and almost my back) trying, I got a stock 850GN stand but still too long. Seemed to me that the suspension height was off kilter.
I got some new rear shocks, but at 335mm (13 1/4") eye to eye it appears these aren't the culprit.
Now I'm thinking the front forks are wrong, but cannot find any specs for GS850 fork length as a complete unit. I have forks with the air cap and length is 800mm (31 1/2") from axle to top of clamp by handlebars. Axle hole is to the front of the forks and about 100mm from the end of the shock. It also appears to have no notch for the speedo gear to slot into to hold it steady.

So, my questions are:
1: Is this a 1979 GS850GN front fork to start with (fork seals correspond to GS850 Models ie:37x 49mm)
2: Is the measurement of 800mm about right (or should it be about 900mm if the axle was at the bottom of the fork)
3: If mine isn't correct, does anyone in the UK have a decent (ie: correct) set for a 1979 GS850GN they'd be willing to part with (for cash or swap)
4: Which modern forks will fit with minimal fabrication (ie: use same wheels and maybe same brake setup)
Thanks

 

[Burque73]

Those forks sure look like they're from an L not a G.

If you look through a parts diagram and then go to someone like these guys that have a cross reference tool, It should tell you what other bikes used that part. Maybe just a google search with the part number will bring up other bikes that used that part.

Looks like the fork for 79 is unique to that year according to the cross reference on this site, but 80 and 81 are the same. Whether you can swap the entire fork from one year to the other I can't answer.

Another note, even with the correct forks I have a bear of a time lifting my 83 onto the center stand. Probably doesn't help matters that my forks and rear shocks are all original and it squats down a bit. Another member here suggested rolling the rear wheel up onto a wood block to lower the stand, which helps tremendously. I cut two blocks, one for the front as well, and I can now ride up onto the blocks and lower the stand while still on the bike. While not my preferred method, it works. I still prefer to stand next to the bike and it doesn't hurt my back any more using the stand.

Hope this helps.

 

[Guest]

Thanks for the link - looks like I do have the L Front Forks.
Does anyone have the stock measurement for 850 fork assemblies (axle to top)

 

[Guest]

Leading axle forks, an 'L' mudguard and slotted discs all indicate that you don't have the original set-up.

 

[2BRacing]

Thanks for the link - looks like I do have the L Front Forks.
Does anyone have the stock measurement for 850 fork assemblies (axle to top)

On my 1981 model which also has the air forks, the length is 800 mm from axle centerline to top.

 

[Burque73]

On my 1981 model which also has the air forks, the length is 800 mm from axle centerline to top.

My 83 is exactly that as well. Don't have a metric tape measure but it was 31- 7/16" which is pretty darn close to 800mm.

 

[Steve]

Another responder here without a metric tape, but I have two measurements for you.

My wife's '82 850L has the leading-axle forks like yours. I measured from the top edge of the air cap (not the top of the cap, just the edge, right above the fork tube) to the axle center, it is right at 32 inches.

I then checked the same points on my '80 850G, which has the axle under the fork ends, the measurement is 31 3/4 inches.

You can easily run into handling problems when you mix and match components in the front suspension. Functionally, there is nothing wrong with leading-axle forks, but you also need the proper triples to match. When Suzuki installed leading-axle forks, they did not simply push the axle ahead of the fork tubes. They actually left the axle in place and moved the fork tubes back, by straightening the angle on the triples to move the tubes back. Of course, this caused interference with the front edge of the fuel tank, so it was made shorter or moved rearward a bit.

If you don't change the triples and simply install the leading-axle forks, you will lengthen the wheelbase a bit, but you will also reduce the "trail". Trail is what enhances the stability of the bike by providing some self-centering in the steering. Reducing it very much will make the bike rather twitchy.

.

 

[Guest]

Thanks for the replies. I have now sourced and fitted a G Set of forks. Length from axle to top of clamps is approx the same at 800mm ish. Looks like the PO used entire front end from the L as I am now looking for brake spacers/new calipers to bolt on.

 

[Guest]

This is the front end now.