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Discussion Starter · #1 ·
I started fooling with my KX65 pit bike (I know this isn't everyones' flavor-- see the 2 stroke forum) on the track some, and looped the bike out big time-- twice!!



Here's where I think the issue is. I looked at the Race Tech chart to calculate the fork spring rate, and it showed 6.1 and .34 (front) spring rates. I know that the Fox Podium I've got out back has a 6.1 spring rate. This is what PR2 put on it w/out me saying anything to them about what the RT chart said. Now.. in the front-- I put a set of Minibike Springs KX65 "Adult" springs in without even asking what the rate was. I am an adult...?



After I looped the thing out a couple of times-- I called Rob at MBS, and he told me that the rate for those springs is .43, and 4.6 with the progressive coils at the bottoms. I'm thinking that I need the .34 springs, and I need to have the holes on the damping rods welded shut, then re drilled smaller-- (valving) in order to help control the rebound rate-- in order to avoid a repeat loop out performance.



My question is this-- what if I pulled out one of the MBS super stiff springs, and dropped in a stock 65 spring-- .27. Would you average the two and come up with a .365 spring rate like what I have in my stock 110? I have one stiff BBR spring, and one stock spring. I'd rather try that with the welded damping rods to see if the results will be any better than what I've already had before I spend $140 on custom wound .34 springs. It would probably be slightly stiff, but a step in the right direction compared with the .46 rate that threw me off.



Anyone know what they're doing with suspension? I'm learning... the hard way! --L*64
 

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Here's what I know ..

What it sounds like you are dealing with is either an overly quick rebound issue up front or the back end is packing ?? ( not rebounding quickly enough )

To get an Idea of how a suspension should react , you need togo to BBR's web site and then go into the video section for suspension set up .. Watch how when he pushs down on the bike how both end move up and down at the same time . This is key !!!



Unfortunately when it comes to damping rod forks , it is tuff to get every aspect of the suspension to be right with out alot of work .





Golden rule #1 ..... Make sure your spring rates front and rear are for YOUR WEIGHT !!! If they are not ? You will be fighting an uphill battle ... ;)

Yes ... after you get the bike dialed in really close and you still feel you need a diff spring .... you can bump up or down , but that's another issue in it's self .



Then you start to figure out what is needed for compression adjustments and then rebound adjustments via diff weights of oil and sizes of oil orifices in the damping rods .



For the kx65's .., all's I've found was a high .3kg and maybe even a .4kg availble??



How much do you weigh ? I believe for a 175lbs guy , a .4 or .5kg spring is called for ? I forget at this time .. :)





I would try one stk and one hd to get an idea of how it would feel with a lighter spring installed .

Run this ofr a while and try diff weights of oil to see what happens .



Progressive springs are what you will need for sure !



BBR makes kx65 springs ???? :confused:
 

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Discussion Starter · #3 ·
Good info. The rear isn't packing I don't think. as the Fox Shock that's on there was set up just for me by PR2. I think the .46 springs are way too stiff, and the forks offer very little rebound control for this amount of spring.



I was going to try and pull out one of the heavy MBS springs, drop a stock spring in one side, and weld and redrill the damping rods to see how that feels.



If it's better, then I'll spend the jack on some custom wound springs around .34 kg. If I still can't get it to feel better, then I'm pulling my shock off, putting the stock shock and fork springs back in, and selling the bike. I'll get a 150R then I had one and loved the thing!



BTW-- BBR doesn't sell any KX65 springs. I have one heavy BBR spring, and one stock spring in the forks on my stocker 110. It actually works pretty good. --L*64
 

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Stick with it bro !!! Don't give up !!!

I'm still learn'n as I go along too . :)



All the stuff we learn will carry over to all of our other bikes we set up from here on in .. ;)



I know when I get the coin , I'm go'n for the works internals for my 65 forks .



Twin clickers baby !!!!! :cool:
 

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From what I have experienced with my 65 road racer with the MBS .43 springs is now that the bike is sprung correctly for my weight (185lbs) the compression and rebound valving cant keep up.

You have to figure the valving was designed around the stock springs and a 60lb rider. Now you put these jumbo springs in with out changing the valving and the rebound simply cant keep up causing that nasty fast rebound which is probably putting you on your a$$. The crazy 65 power band does not help much either, especially in MX.

I to am going to experiment with welding up the rebound holes. From what I hear there are 3 holes in the rebound and 4 on the compression. I plan on welding up one on each. I am hoping this will take out some of the initial fork dive when jumping on the brakes and also add a little more rebound dampening. I figure with the reduced amount of holes in each it will react better to fork oil changes.
 

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Re: Stick with it bro !!! Don't give up !!!

JohnnyB said:
I'm still learn'n as I go along too . :)



All the stuff we learn will carry over to all of our other bikes we set up from here on in .. ;)



I know when I get the coin , I'm go'n for the works internals for my 65 forks .



Twin clickers baby !!!!! :cool:


Can you post a link to the internals you speak of? Is it the same as the PAX kit for $450?
 

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Discussion Starter · #8 ·
Yeah! It's what PAX sells. I spoke with PR2 yesterday, and they told me that we;ding the holes on the damping rods won't do much except for possibly lead to oil lock...



The Manitou internals are about the only way to get the forks to work properly. I was going to do that Manitou setup with my 110 KX65 forks because they are stiffer than the forks on the 65. The KX65 will only be using .36 springs, so I may try and see how that works out with just springs and 15 wt. oil. --L*64
 

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Luckystar64 said:
Yeah! It's what PAX sells. I spoke with PR2 yesterday, and they told me that we;ding the holes on the damping rods won't do much except for possibly lead to oil lock...



The Manitou internals are about the only way to get the forks to work properly. I was going to do that Manitou setup with my 110 KX65 forks because they are stiffer than the forks on the 65. The KX65 will only be using .36 springs, so I may try and see how that works out with just springs and 15 wt. oil. --L*64


I read a post on SMJ by Deberhind (Ohlins Dave) and he suggested the welding up of the holes trick. He set up my Ohlins rear shock with the road race valving and correct spring for my weight and it was spot on right out of the box. Just a little clicker adjustment and instant perfection. So if he knows anything about the forks like ha knows the shock I think it will work. Worse case scenario I re drill them.

I'll let you know how it works in a few weeks when the weather lets up.
 
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