Hissing Right Fork

[79beem]

After my handling wows see "wobbles", I thought I'd nailed the problem, but I still have a wee bit of wobble ( not as bad since I inflated tyres properly). During my various investigations I noticed fork oil sitting around the top of the filler screw. I changed the oil as it was about due and replaced the tatty fibre washer with an O-ring.

So today I had the bike on the c/stand and when I brought her down "H-I-S-S-S-S".

Stupid question time.
If in theory the washer is sealing could the fluid/ air be escaping from anywhere else? Hiss if definitely coming from top of fork.

[Barry]

There are only 2 place for the air to escape; the filler screw seal and the fork top plug that the filler screw goes in to. The top plug is retained by a C clip and seals against the stanchion bore with a large O ring. It's possible that O ring is damaged.

I suppose air could come out of the fork seal but only if there was almost no oil in the fork.

Too much oil could cause excessive air compression. How did you check the oil level ?

The only really accurate way is with a dip stick down the filler hole. You should have 35mm  (minimum of  20mm and a maximum of  50mm) above the damper piston top.

[79beem]

Hi Barry,
I put the reccomended amount according to the clymer manual,roughly 180mm? without checking. I'am not familiar with the dipstick method. How long does the dipstick need to be? Dont want to loose it in the fork.  

[Barry]

190cc is the usual refill volume so 180 cc should be ok.

To check the level with a dipstick you are trying to measure the oil level above the top of the damper rod piston so you just need something long enough to reach down through the centre of the spring until you hit a stop. That's the damper rod piston there's nothing else to hit.  A length of welding rod is ideal. Any small diameter metal rod around 2 feet long would do. I used to use welding rod but discovered the dipstick from my car actually works better because it's easier to see the level with clean oil. I even have the 20mm 35mm and 40mm lines scribed on it now.

The oil level is not ultra critical but it must be a little way above the piston or air would get drawn in and the damper valve wouldn't function properly. The minimum 20mm is probably because once the fork is in motion oil squirts out of the holes in the piston top and coats the full length of the spring which will tend to lower the oil level a little.

I just measured my car dipstick and it's 19" long so that's all the length you need.

[79beem]

Cheers Barry,
I have new progressive springs coming within the week from motorworks so I'll wait for them before I check the plug O-ring.
I'll check oil level tomorrow.
Thanks for the advice
regards
Ian.

[79beem]

New filler screw washer was the remedy