Showa 43mm Forks Oil Level?

Hi Guys,
A bit of help needed with the correct air gap for the 43mm non-adjustable Showa forks fitted to my 600 Monster.

Both the Ducati workshop manual and the Haynes one only seem to give specs for Marzocchi forks and the 90mm air gap quoted seems woefully inadequate. By the time you fit the spring and top tube there is virtually no air gap left which can't be right? There definitely wasn't the same amount of oil that came out as I had to put in to achieve the 90mm gap!

Any help would be greatly appreciated

 

Hi Keith916, both manuals say to measure the Marzocchi firks with the springs out and the firks fully compressed. Though I pretty sure I've done forks on other bikes where you measure the level with the springs in like you say.

Trawling the interest seems to suggest different manufacturers do it different ways, but the majority seen to say do it with the springs out as per my manuals.

Nowhere can I seem to find the air gap for the non-adjustable 43mm Showas.

 

Thanks Derek, the capacity you give is pretty close to what I added in order to get a 90mm air gap. So that bit is giving me more confidence.

However, even with the slightly larger 90mm air gap, by the time I replace the sprin and preliad tube the oil is nearly level with the top of the slider. Is this correct?

I was expecting far more of a gap, otherwise there would surely be hydraulic lock and no fork movement?

 

No worries mate, the larger oil capacity you found is much closer to what I was expecting

 

Ok, a bit more info on this. Having now cleaned up the forks I've discovered the tiny model number stamped at the bottom of the leg.

The forks are unadjustable Showa GD051-50's, which from what I can find on the interweb, We're only fitted on late model carbed Monsters onwards (mine is a 2000 model year).

Still don't seem to be able to find the air gap on the internet, but I drained out about 380ml (had some spillage) from the other leg. This is roughly the same quantity as specified for the Marzocchi forks, but would gives an air gap around 180mm. This is way more than anything I've yet seen, though the bike has handled fine all these years?!

Any help greatly appreciated

 

Yeah, getting the same feeling Keith. Will give Rich at Loiugi Moto a call tomorrow.

I'll post the details on here once I've got them in case it helps someone else in the future.

 

Hi Mate, I did get a reply from one of the members in the MonsterUK forum, who had found official specs for this model of fork from somewhere, showing 440ml with a 135mm air gap.

That was pretty close to what I thought I had drained out (before a spillage occurred!), so I went with it.

I used Motul fully synthetic and made it up to 7.5w which appears to give the compression and rebound that I was after. However, please note that my M600 is still on SORN, whilst I concentrate on the restoration of my Ducati single, so I've not been able to road test the results.

Not sure how close these specs would be for the 900 would be though?

I'll try and find the original reply I had on the Monster forum and post it up here.

 

Ok, this is the reply I got on the UKMOC forum, the air gap I quoted as 135mm is what I measured after following the quoted oil capacity:

"MY02 620/750ie, which I believe uses the same non-adjustable Showa fork:

0.440 litre Shell Advance 7.5 fork oil or Dontax TA per leg.
The factory manual doesn't give an air gap.
... and somewhat confusingly says 0.410 litre elsewhere (so I'm assuming that's for a oil change rather than a rebuild)

Pour in approx. half the oil, to cover the damper holes and pump the damper ten or more times, at least 150mm per stroke, then pour in the remaining quantity."