Changing front fork springs?

[blkkat06]

OK, I'm new around here and so is our 750 Kat. It's actually my Son's bike, but I'm the family mechanic, so I've been reading post after post until we've developed a starting plan. An exhaust was first & we installed the two brothers slip-on last week. We have plans to smooth the welds in the header pipe and install an Ivans jet kit and maybe go to a 47 rear sprocket. But most importantly we need to firm up the front end and just received the race tech .95 kg/mm springs. I've read 10 posts on picking springs and setting sag/preload, but can I get them in there without completely disassembling the front forks? With only 1100 miles on the bike I was hoping for a shortcut? If not, does anyone know of a how-to available anywhere? Thanks, guys

[Black_peter]

To change the springs just pull the top caps and remove the spacer then the spring. Make sure you get as much of the oil back into the folk. One thing about the 98 kat is the lack of fork oil drain screw. It's a really good idea to block up the front end. That way you're not working against the weight of the bike.

[blkkat06]

Thats what I was hoping to learn. Thanks for the help. I was originally going to simply put 3/4" spacers to increase the preload(we measured static sag with & without rider), but once I rode the bike I saw how soft the springs were and decided to get the race tech springs. Is it likely that I will need to cut the spacers supplied with these springs 3/4" longer than stock or do we need to scratch that and start over? These springs are abut 50% stiffer than stock so unloaded and loaded sag would be less, therefore I would guess a 1/2" longer than stock spacer would be the ticket. I'm trying to estimate it as accurately as possible because this is my son's bike and he's already left for school. I'm trying to complete our mod's and get the bike back to him next week. I just realized that all of the assumes that the RT spring is a direct replacement for stock. I've seen springs where the design length was completely different and compensated for with a change in spacer size. None of the posts I've seen suggest that this is the case with the Kat, so maybe I should just go do it! I am definately open to advice and suggestions. Thanks

[steves]

Um, I'm not expert on forks... but I think the point of adding the spacer on the kats is to compensate for the progressive fork springs.... so with the race tech springs... I'm not sure you would want to up the preload on them.... but I'm not the correct person to ask about that.

[md86]

Or just call Racetech and ask if you'll need a different spacer . I'd bet they'd tell you if they CAN . And USUALLY you can get springs rated for riders of a specific weight as well if you go aftermarket .

[Black_peter]

Um, I'm not expert on forks... but I think the point of adding the spacer on the kats is to compensate for the progressive fork springs..

Nothing can replicate progressive springs in forks. This will explain;

http://www.katriders.com/forums/viewtopic.php?t=30432

All the added spacer does is preload the front spring. The stock front spring is pretty soft (I have no idea what the rate is) but I'm guessing that the racetech spring is closer to 1kg/mm. You may find based on your riding and weight that you might want to reduce it however if the racetech spring is the same length as the stock one you don't have a lot of room for reduction.
If the racetech spring is progressive you may not need to.

[steves]

Um, I'm not expert on forks... but I think the point of adding the spacer on the kats is to compensate for the progressive fork springs..

Nothing can replicate progressive springs in forks. This will explain;

http://www.katriders.com/forums/viewtopic.php?t=30432

All the added spacer does is preload the front spring. The stock front spring is pretty soft (I have no idea what the rate is) but I'm guessing that the racetech spring is closer to 1kg/mm. You may find based on your riding and weight that you might want to reduce it however if the racetech spring is the same length as the stock one you don't have a lot of room for reduction.
If the racetech spring is progressive you may not need to.

Right... the spacer increases the preload on the stock springs....

[blkkat06]

I installed the new springs yesterday and went for a pretty good ride today. It really made a difference. The stock springs were rated at .62 kg/mm according to race tech and the new ones rated at .95 kg/mm. I used the stock spacer and added a bolt and washer on each side for an additional .5". The sag with rider is about 35mm. I probably could have used an additional 1/4" of spacer. A big thanks to all who chipped in with good advice and tips. Next weekend - Ivan's jet kit!

[md86]

static sag of 35mm is pretty close to what you want . I'd call it a day .