Checking fork oil height

[StrayAlien]

Hi all,

With the forks in place, can I just loosen triple clamps, unscrew fork tops, take spring out and check fork oil height?

... and then do the reverse to put it back? (without anything going twang?)

(I realise they'll be on an angle, but checking the height at the side of the fork, not the front or back, will negate this I imagine)

Many thanks.

[tanto]

In short, you can. I did the same a couple of days ago.

You will need to get the front of the bike off the ground and remove the front wheel. Loosen the upper fork pinch bolt that lies close to the fork top nut, loosen the handlebar clamp bolts, then back out the fork pre-load adjuster as far as it will go. Now you can get a spanner on the fork top cap. Unscrew while hold the pre-load adjuster.

Here´s the important part. To measure the oil level you will need to compress the fork stanchion to remove the fork stopper seat. That's why you removed the front wheel. Once the stopper seat is out of the way, there is sufficient room to get a wire down the fork tube, past the washers and spacer mounted on the fork piston assembly.

FWIW, going from the top of the fork tube, I measured one fork that I had just rebuilt with a new oil seal, and compared it with the other fork leg. At the angle I had the bike and the point I measured from, the distance to the oil was 295mm. A 30cm/12in carb adjustment screwdriver made a good dip-stick. Note, my forks have Rick Oliver's spring kit fitted, so the oil level on standard NC30 91-93 forks will measure differently.

[magg]

IMHO, I would:

1. raise the front of your bike using a steering stem stand
2. loosen the upper triple clamp / fork leg pinch bolts
3. unscrew the fork caps
4. raise the front wheel to completely compress the front forks (fork caps and springs will extend out of the fork tubes)
5. unscrew the damper rod to fork cap locknut
6. unscrew fork cap ( count the number of turns to use during reassembly)
7. remove washer, spacer and spring.
8. using suitable tool measure the distance between the oil height and the top of the fork leg

Standard oil height varies between models but is generally 110-130mm. As a track bike you may need closer to 110mm given compression under heavy braking but IMHO would will provably need to experiment to get the best number.

[magg]

One addition I would make to my earlier post would be that if you cannot completely compress the forks without the front guard touching the support stand, then you will have to remove the guard and perhaps the front wheel.

[Drunkn Munky]

This is obviously a stupid question but i cant get my head why you need to loosen off the top tripple and clip ons? Granted ive never attempted taking the forks apart on the bike before but i still cant see why this needs to be done,

[porndoguk]

This is obviously a stupid question but i cant get my head why you need to loosen off the top tripple and clip ons? Granted ive never attempted taking the forks apart on the bike before but i still cant see why this needs to be done,

As it applies pressure to the fork caps "fine threads" wouldn't wanna be stripping them now

[magg]

As porndoguk said, tight fork top pinch bolts will make it virtually impossible to unscrew the fork caps without damaging them, if you can even manage to turn them. Tight clip-on clamp bolts are not a problem, have removed the fork caps many times without touching the clip-on bolts.

[Drunkn Munky]

I follow ya

[Neosophist]

[quote="magg"]
5. unscrew the damper rod to fork cap locknut
6. unscrew fork cap ( count the number of turns to use during reassembly)
quote]

Do you mean remove the fork adjuster from the cartridge on later style forks?

Your not supposed to remove this, it's stated in the Haynes and Honda manual.

Your supposed to screew the whole inside out of the fork cap bolt. If you remove it from the rod you loose the correct adjustment of the brass adjuster.

[StrayAlien]

Funny innit, I thought it might be straight forward but as with anything suspension related. It aint!

I've got a race day in three days so I've run out of time and can't do it before before then. Pressure is off after that and I'll get into it and post pics/instructions here. Changing the fork oil height is one of those things that should be easy enough to do in the pits on a track/practice day (and I've seen people doing it with 400s).

Some time ago I watched someone get these forks apart and refurb them and the oil height was set back to roughly what is was which was in the 200mm ballpark. I find that it should be 122mm but I can't for the life of me recall if that measurement was with fork compressed or extended. So I have to do it again to be sure!

Back soon ...