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Looking to get some advice on the suspension on my 1989 Suzuki RM250.
Its currently fitted with the standard 1989 stuff, and its horrendously soft! Its also terribly valved and just isn't working properly at all.
What are the best options for this bike? I'd like to keep it genuine 89 if possible but I've yet to find any stiffer replacement fork springs for the forks. I've seen others running newer model forks from 1992 right up to 1999, but not sure if this is a good route to go down or not as it could end up getting very expensive.
If a newer model fork is the best route to go down, what year forks are best?
Any advice would be greatly appreciated!
Here's some pics of the bike from the weekend.....
Its currently fitted with the standard 1989 stuff, and its horrendously soft! Its also terribly valved and just isn't working properly at all.
What are the best options for this bike? I'd like to keep it genuine 89 if possible but I've yet to find any stiffer replacement fork springs for the forks. I've seen others running newer model forks from 1992 right up to 1999, but not sure if this is a good route to go down or not as it could end up getting very expensive.
If a newer model fork is the best route to go down, what year forks are best?
Any advice would be greatly appreciated!
Here's some pics of the bike from the weekend.....
If you could get measurements of your fork tubes that would be ace thanks! Although im 99% sure they wont bolt up into the 1989 clamps.
There's a set of 91 forks on Ebay I like the look of for £100 which is cheap, so may consider that route. 91 forks have a slightly larger lower diameter than 1989 I believe?
I've already put a slightly heavier weight oil in, and gone up 20cc per leg which helped a little. But the first half of the stroke is still far too soft. How large a pre load spacer could I get away with without binding the spring? I've yet to try that route.
The Shop
As you're finding out, the 41mm KYBs on your bike has non existent spring options......and they need a pretty big jump in spring rate to do anything effective.
The '91 Showa lower leg was beefed up to 45mm and that gave it a more rigid feel to the front end......but the frame was also strengthened quite a bit in '91 and that helped with front end feel as well. With the '91 forks you should be able to use the same front wheel and brake from your '89.
If money wasn't an object (and keeping the bike period correct), I would put on '98 Showa conventional forks or '99-'00 RM250 49mm forks.....but you would need the entire front end.
My '90 RMX with '98 RM250 forks
From looking at all the options it seems as though a swap to the 1991 fork will be the best and easiest option. I think going to a 92 onwards front end will be too expensive and too slow to achieve with all the parts I would need to get.
My local suspension guy can source Eibach springs so that's good news if they are still making them for 91 forks.
Carl 44 - Interesting to know! I think coming of a 2015 RMZ450 onto the 89 RM250 doesn't help, but the suspension definitely isn't right. I've got all the clickers wound fully in and the forks and shock are still bottoming out and rebounding like a pogo stick! Chances are a good service will do them the world of good as well. I'm based in the UK so cant realistically use Factory Connection, but I could always email them to see if they can offer advice. Thanks for the heads up.
I measured my stock springs on my 92 RM 125 and they made me stiffer (46 or 48...I forgot) springs for $139.95 OTD. Only took about a week. Made such a huge difference...I put a 5.2 spring off of a newer KX450 on the rear and my suspension can handle anything I could possibly do to it. So much easier than swapping to a "newer" front end setup.
The 91 clamps and forks bolt right in, with the only issues being the steerer stops not being right on the lower 91 clamps for the 89 frame. This isn't a major issue though and I will get some stops welded onto the 91 clamps to suit the frame.
The other minor difference is that you will need longer brake caliper bolts, as the mounting points at the fork are wider that the 89, meaning that the caliper bolts from the 89 are too short. Again not a big deal and easily sorted with longer bolts.
The forks are currently with my suspension guy getting serviced and set up. I'm hoping to get the clamps sorted this week also.
I will post an update picture once its all complete.
Thanks again for all the help!
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