fork improver kit

[rough rider]

hi , going through some gear in my fathers shed recently and found an old CZ fork improver kit made by RPM from the 70's . kit fits motorcross and enduro cz's all models to 74
kit consists of a alloy wave washer approx. 7mm thick that replaces the valving , and a alloy 'hat' which sits under the spring and on top of the damper rod ,
 step 31 on instruction sheet states ' your new super front forks are considerably softer '
 
has anyone seem or used a kit like this ? what does it improve ?

just trying to work out if its worth going to the trouble off fitting it or not , was thinking of fitting it to my 74 125 as the forks were quite stiff and I ended up running 5 weight oil in them to soften them up , not to bad now . instructions say when using this kit oil should be 10 to 30 w for motorcross and 30 to 50w for cross country


 
 

[shortshifter]

Roughy,I bought an nos no1 improver kit and fitted it to one of my bikes,sounds similar to what you have.I think there was an improvement,but I'm a wobbler so I reckon if you were going harder the improvement would be more pronounced.

[tony27]

Sounds like a number 1 products kit, I made up a few sets a couple of years ago for a couple of guys. I didn't get round to fitting a set to my forks as I'm running the grand prix cycles/moto-x fox replica aluminium damper rods from Charlie Richardson, the guys that fitted them reckoned that it did make the forks plusher
Can you put up a photo & I'll tell you if they're the same

[rough rider]

here is a pic of the kit hope it works first time ive used photobucket

[firko]

That's the same idea as the Number One kits. I've got a CZ kit and one for 34mm Yamaha and Suzuki forks. I used them back in the day but can't recall any startling improvements to my forks.

[tony27]

You're missing a washer for each side, I'll see whether I can find the email that had the dimensions. It's a scan of 1 of Peter Drakeford's CZ files. Pretty sure I still have the printed off version somewhere if I can't find the email

[tony27]

Can't work out how to save it to photobucket but could email it to someone if they can
Missing washer size is 30mm OD, 21.5mm ID & 3mm thick, file says original part was brass but the sets I made were aluminium

[rough rider]

thanks tony , I have the washers you mentioned they are the dimensions you listed and as you say are brass . found them in the bottem of the box the kit was in , wasn't sure if they were the ones for the kit but now you have listed the sizes I know they are .

[tony27]

My pleasure. I'll try something tomorrow morning when I get home from work with the pdf file & see if I can get it posted up, has lots of info on damper rods as well as the drawings for the kits. Not sure if I ever put up a shot of the alloy rods next to the originals but I'll get 1 up then as well 

[tony27]

The pdf printed then scanned as a jpeg


The aluminium damper rod at the top is the moto-x fox replica, gives the maximum allowable travel for pre75. If you look closely you should be able to see the waisted section through the middle much like what is described above

[rough rider]

fitted my kit to my 125 today , very easy to do , what weight oil do you use ? gives a range of 10 - 30 w for motorcross , I was using 5 before because they were so stiff
thanks

[shortshifter]

From memory I think I used a 10w Yamaha fork oil for this.Do you have beefed up springs?

[rough rider]

nah springs are stock for all I know  , thanks for the reply
need some new ones in my yellow tanker though , last meet they were a bit soft , ended up removing the top caps and fitting a 3/4 socket on top of the springs to stiffen them up a bit , worked well ,LOL ,using 30w oil in the forks in this one and they are not to bad , not sure if they have been modified internally though