Can stock fork valves be modified? Smoohing edges?

[Robin13]

Can stock fork valves be modified? Smoothing edges?

I was wondering if smoothing the edges of my 1994 cr125 fork valves would make the fork smoother. The valve of the fork has very square ports compared to those of the GV, wich look really round, big and smooth. Or do you think it would not make a difference. Has anybody ever tried this? Maybe some tips on tuning the valve? Thanks alot.

 

[marcusgunby]

You have to open up the ports a reasonable amount to get the fork to feel different.Like going from 2.8mm holes to 3.5mm.

 

[binder929rr]

ya, i think shops bore them out as far as they can get them...only problem on forks is that you have to do each side exactly the same to get them to handle the same.

 

[hockeyboy]

I used a very small drill bit to drill holes between the square cut outs. On my base valve there were 4 square holes. Now there are 4 square and 4 round holes. My forks used to be harsh on square edged and stutter bumps. Now they seem plush. I figured that if I damaged them, I could always replace them with Gold Valves. It cost me $1.50 for the drill bit, and a couple of hours to remove the valves, disassemble them, drill them, reassemble them, and reinstall them.

 

[marcusgunby]

If you bore out the ports or add some you are effectively softening the stacks-next time remove a few low speed shims and see if it has a similar effect.

 

[binder929rr]

If you bore out the ports or add some you are effectively softening the stacks-next time remove a few low speed shims and see if it has a similar effect.

yes, this is true but the valve is still causing resistance. there is better tuning within a high flow valve.

 

[marcusgunby]

yes, this is true but the valve is still causing resistance. there is better tuning within a high flow valve.

i disagree,i think you can tune with any pistons on the market.

 

[bclapham]

IMO modifying the pistons is a bad idea- you can damage the surface where the shim seals against the piston.

just change shims!

 

[hockeyboy]

If altering the base valve is a bad idea. Why does everyone install gold valves. The gold valves increase flow to the shim stack. Some forks are known to have overly restrictive ports in the base valve. If you are going to install gold valves anyway, whats the harm in trying to alter them. Depending on the type of bike (fork) On some forks changing the shims would be the first adjustment.My bike is known for having less than perfect forks (KDX220) Gold valves(modified base valves) are part of the cure.

 

[marcusgunby]

The kdx is a special case as it has a very out dated fork, people use the gv as its the main one where you can do your own tuning, its not really the best option for most forks, often you are putting in a valve very similar in port size to the one you are removing, eg the new showas have huge ports.

Ive heard people rave about how good a small port piston is eg mx tech and pro action so i cant see how they can be restrictive.

 

[tbrooks]

what are you thinking ?

sure you can drill or grind on your valve ( piston ) if you don't care about your forks . Cutting on your valve will cause side loading and cavitation due to uneven surfaces and rough edges. Simply changing shim stacks will do well enough for most people , as said eailer in this thread some forks have to have gold valves in order for them to work properly. The use of gold valves in most late model motocross bikes is a waste of money for the average rider, the big gains most feel comes from the shim stack :ohmy: