HI guys,

Quick question. I have a fork cap that's shooting oil everywhere whenever the fork is compressed. Do these look like normal caps? It looks like there is a screw in the middle that has been shaved. I can't really see how these are serviced, can they be and do they look standard?

Cheers

 

 

 

Edited September 14, 20187 yr by cornishflyer
Forgot some details

The 0 in the top of them is just a stamp. Most of that style of cap have them. You have to remove the fork caps to service them. Inside you will find an 8 mm nut holding a washer and a spring. Pull all of it off and clean everything. Poke a bit of wire into the hole where the oil is coming from and try and make sure it is clean. Sometimes they stop squirting and sometimes they don`t stop squirting. One thing you can do is just spin the fork legs so the squirt misses your eyes and the bike when the caps are screwed up tight. Don`t forget to loosen the top clamp bolts to get the caps off. They are standard. Graham. 

Edited September 14, 20187 yr by bullylover

Thanks Graham, excellent information 

I've never stopped these things spewing oil other than by blocking the hole. Some will say that causes pressurisation in the fork as air can't escape but I've never had any issues doing this.  In the bottom of the fork spring there is a deflector which is presumably to stop oil being sprayed out of the top of the damper rod like a water cannon, these are often missing after numerous rebuilds over the years. Whether they help stop oil being forced up the tube and out of the caps I don't know - possibly...

Sealing off the vents allows for easy fork spring rate tuning by changing oil height if you are into that sort of thing.

The KT250 came with vented caps too and the oil deflection technology in them is quite clever but I still replaced them with sealed caps so I could tune the fork spring rate.

Thanks to all of the replies. I ended up sealing the cap off, the fork feels much better now as well, more progressive even.

10 hours ago, cornishflyer said:

Thanks to all of the replies. I ended up sealing the cap off, the fork feels much better now as well, more progressive even.

 How did you seal the caps?

I use a drop of araldite

 

On 9/14/2018 at 2:27 PM, feetupfun said:

Sealing off the vents allows for easy fork spring rate tuning by changing oil height if you are into that sort of thing.

The KT250 came with vented caps too and the oil deflection technology in them is quite clever but I still replaced them with sealed caps so I could tune the fork spring rate.

 Have you ever experienced pressure build up beyond what you wanted, or do you have manual vents on your caps? I see Bultaco UK sells a pair with Schraeder valves.

8 hours ago, motovita said:

 Have you ever experienced pressure build up beyond what you wanted, or do you have manual vents on your caps? I see Bultaco UK sells a pair with Schraeder valves.

No problems with pressure build-up and no vent valves fitted. The oil height is set to give the air spring effect I want when forks have reached normal operating temperature

On 19/09/2018 at 12:22 AM, motovita said:

 How did you seal the caps?

I used some silicone sealant in the inner vent holes, waited for it to dry and then held in with a large washer.

 I was considering sealed caps to slow fork compression on hard drops where the fork bottoms out. I found that I could buy new springs for less than new caps, my springs appear to be original with added PVC spacers so I decided to go that route. I decided to try shortening my springs first. I cut 50mm off of one spring and added 45mm of PVC spacer in it's place with good result. My 199A fork still has good compliance on the small stuff and steers well but is a little more stable on steep, sudden, drops, where it still bottoms out. I may play with the other spring later but I'll ride it as it is for a while first.

As the vent holes are now blocked this will make the fork tube seals work harder as the internal pressure build up has to be released somewhere, so this mod may cause the seals to leak (as mentioned previously) the pressure will now be blowing out through the lips. This is probably better than a face full of fork oil! I thought Bultaco used a tiny ball bearing on top of the tiny spring in the fork cap to act as a one way valve, thus stopping oil ejection.?