Which progressive springs for 550m katana?

[Wallowgreen]

Rebuilding the front end of our '82 550M katana restoration project and I want to install new progressive springs. The progressive web site doesn't have that particular machine listed so I looked at babbitts and their web site told me the same part number (51171-34540) was used on the '81 650E, '82 650E and the '82 550M. The springs listed at progressive for the 650E are 11-1108.

Just called progressive and they say they don't do replacement fork springs for the 550M model!

Any one out there changed the fork springs on the front of their 550M katana and if so what did you fit?

 

[haggisbasher]

You could try http://www.sonicsprings.com/catalog/ they dont do progressive rate springs only straight rate ones but they have a number of options of springing rate for each spring. I just ordered a set for my 750 from them as I'm a big lad and need the heavy spring rate. :lol:

Give them a call or drop an email Rich is really helpful.

Hope it helps
Tom

 

[salty_monk]

Unless you are really bent on replacing them you could try the "poor man's progressive" mod.....

Cut 3-4" of coil off the tightly wound bit of the spring with grinder or dremel (where close together), dress with grinder to make as flat as possible. Replace the same 3-4" with PVC pipe. It ups the spring rate quite a lot & works great on the bikes I've done it on.

Nessism has posted pics of this before on here. Cost is about $2 for the PVC pipe!

 

[Tom R]

+1 on cutting the stock springs. I did this on my 1100 and am happy with the results. I cut 3" off and added 3.5" of additional spacer. I still add 12psi of air to the forks, but they fee better than before without jarring my arms on bumps.
Btw - you want to cut the tightly wound soft side of the spring.

 

[Wallowgreen]

Thanks Dan. Still rather replace them if I can but doing something like that might prove a good option.

This bike's been a real pain in the arse so far! Struggling to get it ready for Reno.

 

[BassCliff]

Hi,

If they're the same Suzuki part number, there should be no issue in ordering a set of Progressive springs for a 650E and putting them in your bike. According to Alpha-sports.com, that same part number was used in the GS550MZ and the GS650EZ.

However, the part number for the '81 GS650EX is a little different: 51184-47400. I mention this only because there may be a little difference in the springs between the model years. But that's what spacers are for, right?

Thank you for your indulgence,

BassCliff

 

[Wallowgreen]

Really? Nobody ever actually been down this road with this machine?

 

[mike_of_bbg]

I've talked to the guys @ Progressive before. Most of their data about older bikes is leftover from a company they bought out. They have no clue about the test methodology or specifics around the tests (for example, for 82 they only have a generic GS550 entry; is than an M, L? They don't know). Their spec sheet is here:

http://www.progressivesuspension.com/pdfs/7100-105.pdf

What I would do if I were you is to decide on the spring rate you want, then measure your springs for their physical size. Find the closest thing you can in the chart. I'm running 11-1115's on my 82 550L, which was the recommended spring for 82 GS550. Though, it's 22mm diameter and I'm sure it could have taken a 25mm spring. Feels nice anyway. Cut some PVC spacers for about 1" pre-load and adjust from there as necessary.

Or do the poor man's Progressive thing.