Progressive Front Springs for 400

[Uncle Bob]

Anyone who has / had a 400 ever get new Progressive Springs for the front forks? HyperPro don't list them and didn't offer anything that might be similar.

I checked the part number ( 51171-46D00 ) and Googled it but as far as I can see they might have been unique to the GSX400SSN. I was hoping they might have been used in something else. While you are, do any adjustable tops fit as well - i was wondering if RGV250 did.

[johnr]

how about gs500 twin? the forks seem a similar size.

[Uncle Bob]

Cheers John, I will check that out - I can have a search about and try and get details for that to compare. I'm also going to remove one and measure it and Hagon (talked them yesterday) said they will see what is similar, which was good of them.

[Uncle Bob]

I haven't measured it but think the 400 has 41mm forks and the GS500 37mm. However, that did get me thinking more about other models (so thanks for that). I found a spec that said the GSX400SSN was 41mm x 620mm long (tube 372mm) and on the same site I went through other models and found the (oh no) the GSX600FW (KATANA!) is the same dimensions. Comparing the parts lists of each they both share lot of parts on the fork internals but the springs aren't one of them. Though I think the 600 would be a stronger spring, which might be handy as I wanted it a bit firmer. I'll see what Hagon say.

[Uncle Bob]

I have the measurements for the 400 springs now:

375mm spring, 1.5mm washer, 150mm spacer, 34mm diameter.

I called Hagon and the guy there could only find the closest match of a spring that was 34mm and 520mm long (existing spring and spacer are 525mm). The force required is 6.3-10.1 kg/cm (as a guide he had Impulse springs at 5.1-7.8 kg/cm (was 520mm as well but only 29mm diameter). To be honest I wouldn't mind it a bit more firm at the front anyway.

What do people think about that? At least Hagon were good about finding something else - I talked to the HyproPro UK people and they wouldn't even look for anything similar saying about legal things and the possibility of me killing myself?!

[johnr]

well assuming that the aftermarket ones are firmer than stock, and the stock ones being a bit longer might be firmer when fitted with the right length spacer than your springs, why not look for some stock 600 kat springs on the bay. there must be millions of the damn things out there, (iirc they sold it here as the rf600) then you can try them out and work out whether you need something firmer still, in which case, you can spend the brass on the aftermarket ones with some confidence that youre part way along the road. at least experimenting with spacers over a set of stock rf springs isnt going to set you back a great deal. as a tip, go to the bank and get ten quidsworth of 2p coins. they make excellent spacer washers being a decent thickness and a uniform size, add or subtract the coins to give you the thickness you need. and once you know the length you want you can make up a spacer from a suitable bit of tube, and you wont have lost a penny, (or two)

[Uncle Bob]

Cheers for advice John. I talked to Dave at Hagen who was also very helpful. In the end given the measurements (spring was actually 35mm) suggested the springs that the second version of the SV650 had, which were 425mm long and 7.1 to 9.5 kg/cm. So I'll start with a 100mm spacer and a few 2p to get it how I like it.

They were so helpful I might even splash out on their 2810 shocks as they do a to order stainless body with black springs version.

Will post results in 400 section for reference.

Rob