Fork oil volume

[cywelchjr]

bikerphil had it correct. The SH is 7.10oz..........right out of the original owners manual. BTW, the H(Venturer) had progressive springs from the factory, unless someone swapped them out.

The 80G has the same air assisted forks as the 81H but came with weaker progressive springs unless ordered with the optional Yamaha fairing that the H came with in which case it got the same springs as the H did, although the fairing and springs were BOTH dealer installed rather than factory installed, so except for the tank and rear shocks an 80G could have left the dealer almost identical to the way an 81H would have (excepting the ignition system of course since the 4R0 didn't start till 81).

[Elevener]

I haven't used Progressive springs in a XS, but I have installed them in other forks. They don't generally give an amount, but rather a 'level', i.e. a distance from the top of the fork tube to the oil, that's with the spring out. They're looking for a specific amount of air left in the fork once it's sealed up. A bit of a PITA to measure, I did one side and kept track of how much I put in and duplicated it for the other side... and wrote down the amount for next time...

Yeah, much better to have the same level in both . Measure down to fluid with the fork fully compressed without spring.

I cut the end off a spray bottle tube then slightly overfill. Stick in tube and pump out. Best way to get them both the same.

[jetmechmarty]

The smaller the volume of air space in your fork tube, the less likely your fork will bottom out. If you don't leave enough space, you won't soak up the bumps because there is too little volume of air to compress. If there is too much air space in the forks you may hit bottom and go bouncy down the road. The factory gave you a volume where no one should experience serious issues. However, adjusting the volume is a way of tuning your suspension.

I just put RaceTech suspension in my forks and they recommend leaving 130mm of air space in the top of the forks. They say tuning range is generally 110 to 150 mm. Traxxion Dynamics sets the level at 120 mm from the top.

[BA80]

I have SH forks on my SG. When I had them apart I didn't notice anything different from the SG internals. Did they just up the oil quantity for the 81?

[Nubian]

Perplexed!

I am now on my second set of OEM seals and both legs are still leaking! What am I doing wrong, I have a new set of OEM's but don't want the same results. I would like to get this resolved before riding season as I have new gear and don't want them stained with fork oil as usual and keep my "Brutus" dry and clean.

[bikerphil]

What are you using to drive the seals in?

[crazy steve]

If the fork tubes are pitted or scratched, no seal will fix that... If the bore the outer diameter of the seal fits into is damaged, you also get a leak.

Phil's right, proper installation of the seals is critical, but they have to have a good surface to seal against...

[Nubian]

BikerPhil and CrazySteve, PVC pipe and the tubes appear to be smooth no scars pits etc...

[crazy steve]

Are you 100% sure both tubes are dead-nuts straight? If one is bent (even slightly), the tube can go 'oval' on you...

[Nubian]

I thought I was but I will take them apart again to make sure, but both leak what are the odds of both tubes being slightly bent?

Are you 100% sure both tubes are dead-nuts straight? If one is bent (even slightly), the tube can go 'oval' on you...

[crazy steve]

I thought I was but I will take them apart again to make sure, but both leak what are the odds of both tubes being slightly bent?

Pretty good if the bike took a 'hit'....

I'll always put some Yamabond on the outer diameter of the fork seals just in case. As far as the inner tubes, if there's any imperfections you can feel with a fingernail, chances are good you'll get a leak.

[Nubian]

Will do that, thanks

Pretty good if the bike took a 'hit'....

I'll always put some Yamabond on the outer diameter of the fork seals just in case. As far as the inner tubes, if there's any imperfections you can feel with a fingernail, chances are good you'll get a leak.

[bikerphil]

When they are apart, check for a sharp edge on the bottom of the upper stanchion. This sharp edge is from normal wear and can be filed/sanded off. It may be damaging the seal when the tube is first slipped thru. If you put the seal in last and drive it home with a long pipe, you don't need to worry about the sharp edge. As Steve mentioned, if the seal mating surface in the lower leg is damaged/gouged with tool marks from removal of the old seal, sand it smooth and use some RTV on the outer edge of the seal.

[crazy steve]

I will make one comment about 'RTV' vs Yamabond. Yamabond 'flows' much better than RTV does (it's actually a pretty good 'lube' when installing seals) and will go into small imperfections much better than RTV. It will even flow into the joint a bit after it's assembled, something RTV won't do. It is a lot runnier, so gobbing it on will make a mess; if you use too much, it will actually drip out.