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Discussion Starter #1
ok guys, i took my RD for its maiden voyage yesterday and the problem with it is how much my forks dive under braking. since the forks are non adjustable, i was thinking about cutting me some pre-load spacers. i am thinking 1.5" might do the trick, but i was going to see what you guys have done. maybe i need more, or less...let me know what you think. thanks!!
 

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You can use a stack of quarters to get the length where yo want it then cut a spacer to match, or leave the quarters. I guess washers would work to, but quarters are cool. The final spacer can actually be cut from PVC, it is strong enough and light and easy to cut. You might also need slightly heavier fork oil to help control the dive. I seem to recall back when I raced an RD400 thatwe might have gone as high as 30wt in the front. I won't recommend that to start with, but keep it in mind. Those forks are not very sophisticated.

Ken
 

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Discussion Starter #3
thanks for the tips ken...i have some 30wt. at the shop ;) can you remember at all about what length spacer you may have used? those forks are about as cave man as you can get from what i can tell. how cool would it be to come up with some 34mm's that had compression and rebound adjusters, maybe some gold valves!? thanks again!
 

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you could add air fittings to your forks. It is kind of a cheat on preloading an you really shouldn't add more than 10 psi but it will preload your forks. A schrader valve, a drill, a tap, and some sealant is all you need.
 

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Tyler, I seem to remember that 1.5 to 2 in was about where we ended up. Geeto is right with the air caps to. We used to either tap and add themto the stock fork caps or S&W and Goki used to make some cool aluminum replacement fork caps that had the air fittings, balance lines and a pressure guage. i have seen them on e-bay occasionally. I don't know of any good 34 mm forks that you could swap out for. Now it just depends on how much money you want to spend on stuff. I believe that there are now 20mm gold valve emulators available that work on RD forks( it was a topic on the WERA BBS vintage board a while ago, do a search), and I believe that Michigan Engineering(thy have a website) can revalve your stock forks too, for a price.

Ken
 

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I have a nice set of NOS air caps I got off ebay at some point.

Air adds a nice progressive effect.

I went too stiff on the front in my bike...helped me fall in the rain a lot. Took 1/2" back out it was better.
JohnnyB
 

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Discussion Starter #7
how does this sound...1" of spacer and 10 psi? i think that might be the best of both worlds. I don't really want to spend a ton of money on the forks ken, as it is just a road bike. heck, i have went over double of what my original budget was already! LOL!! when i go back to the shop to do the finishing up on the bike, i'll build some spacers and see if we have and schraders. the pre-load alone may be enough for me, but right now i can just about bottom the forks by holding the brake and pushing down!! thanks for the help
 

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I started out with 1" on CB550/4 forks, installed on a 220 lb bike....ended up too stiff....and I like stiff forks. It was one of those rare times when Aaron was right about something :)
Bike worked quite a bit better after removing 1/2".
Now your RD is heavier....but 1" and 10 psi seems a bit much...Geets probably has more experience in modding street forks than I do (which would be zero in my case).
JohnnyB
 

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My rd350 front end seemed soft so I added 1" spacers a few months ago and it seemed to stiffen the front end up a bit. I may try to do the homemade air caps though. I've been looking for a pair on ebay. Never thought of making them. Anybody have instructions?

joe
 

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Discussion Starter #10
instructions...take the caps off, mark them, clamp them in a vice, center punch your marks, and drill your pilot holes with a drill press. drill (i'm guessing) a 1/4" hole and thread it with the appropriate hole tap. wrap the shrader valve threads in white or yellow teflon tape or use pipe dope and thread them into your new holes. viola...air caps for your forks. my buddy does hvac work, so i'm going to go grab some PVC from him tonight so i can build my spacers probably wednesday. i'll let you know what i come up with. thanks guys...once again, you all are a HUGE help
 

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every fork is different but 1" spacer AND 10 psi seems like a bit much for me. Stock honda forks will take 14 psi (DOHC bikes that had air forks - this was their max). At 14 psi you start to run in to sticion from the fork seal (or so I am told, my 900 never did this but others who are lighter than me have told me of this problem).

Do one or the other first and see how it feels. The air forks are easier and cheaper to do than taking the fork apart (unless the fork is apart already). remember to fill them evenly or you will end up with a cockeyed front end.

Fill to 5 psi and then work up from there. Be careful when filing ans too much pressure at once can push out a fork seal.
 

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Discussion Starter #12
i think i'm going to try the spacers first, just so i dont have to bust out the machine shop tools again, plus, schraders on top isn't "clean" like i'm going for. i'll let you know wednesday what i find out. thanks again
 
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