Topic: Whats the PSI on air assisted forks?

[78_SaltLick]

I cant find it anywhere. I have a 74 CB550 with a CB650 front end with air assisted forks. I checked the PSI using a tire gauge and it read 35 PSI.....is this right? I know thats right for the tires, but i thought the air assisted forks had to have like 75 PSI. Any help appreciated.

[mick750F]

  Are those aftermarket or factory air forks? I have an aftermarket set-up, still in the box, which I think specs only 5-10lbs. I can check it tomorrow if you haven't gotten the answer already.

Mike

[78_SaltLick]

Man i have no idea. I just got this bike a month ago, and the guy that had the bike before me put them on. i have no way of contacting him now.....is there a way i can check?

[TwoTired]

The 74 CB 550 did not come stock with air assisted forks.

[Paul]

My VFR ...I know it's different, Has Air assist forks. BUT the pressure is 0-6 PSI. quite low. Also if it's similar to what I think, Don't go near it with a tyre (tire  ) pressure gauge or any compressed source. It'll blow the seals in a second. use a bicycle hand pump.

[78_SaltLick]

The 74 CB 550 did not come stock with air assisted forks.

It has an 81 CB650 front end on it.

[Philly550K1]

I've been meaning to learn about mine, too.  My forks are presumably due for a servicing, although it rides fine as is. 

I've heard "low" pressures suggested, too, like 5-10psi.

I don't have the best pic of it, but my fork tubes are connected by a hose, and there is a dial on the left fork, kind of visible in this pic, which presumably gives you a reading on both forks as a "microclimate".

I haven't tried to add any air, assuming the seals aren't up to much.

The forks look stock for a 550, with just this gauge, tube, and a tire-style valve added at the top.

Anybody recognize this stuff?  Is yours anything similar, Lick?

Can I expect to find "stock" stuff underneath if I open this Can of Worms?  I assume I can get away with a fluid change without disrupting anything, but, well, you can see why it's been getting bumped to the back burner....

-jon

[78_SaltLick]

I've been meaning to learn about mine, too.  My forks are presumably due for a servicing, although it rides fine as is. 

I've heard "low" pressures suggested, too, like 5-10psi.

I don't have the best pic of it, but my fork tubes are connected by a hose, and there is a dial on the left fork, kind of visible in this pic, which presumably gives you a reading on both forks as a "microclimate".

I haven't tried to add any air, assuming the seals aren't up to much.

The forks look stock for a 550, with just this gauge, tube, and a tire-style valve added at the top.

Anybody recognize this stuff?  Is yours anything similar, Lick?

Can I expect to find "stock" stuff underneath if I open this Can of Worms?  I assume I can get away with a fluid change without disrupting anything, but, well, you can see why it's been getting bumped to the back burner....

-jon

No, mine are different. I did some research, and what i found is for the 650 i think the correct PSI is 15, with a max of 36 PSI. So i think im okay, but this was from another forum from someone that was guessing also. Id like to find an online manual so i can actually see what PSI is recommended. I know theres somebody out there that has a 650 that can answer my question.....but then again would the PSI recommended work since the bike itself is not a 650?

[cb650]

No way 36!!!  I'd have to look it up at work but under 10 sounds right.  Do the forks know what bike they are on?  Might need less psi for the lighter 550 but how much lighter is it. Not much I bet.



                                 Terry

[mick750F]

   I checked out the aftermarket set-up that I have in my shop. It's from MC Enterprises. These aftermarket kits were common back in the day. I'd say it's questionable as to whether they make much of an impact in ride or handling. The MCs call for 5-10lbs. These aftermarket kits simply replaced the cap at the top of the tube. All internals should be stock. You would have no problem running these with no pressure. No pressure equals stock set-up. I have no idea if 650s came with air forks. If they did you need someone elses help. I'd try them with no pressure then add 5 lbs. and compare...and take it from there.

Mike     

[78_SaltLick]

No way 36!!!  I'd have to look it up at work but under 10 sounds right.  Do the forks know what bike they are on?  Might need less psi for the lighter 550 but how much lighter is it. Not much I bet.



                                 Terry

i checked mine with a tire pressure gage ( little hand held ones) and it read 35 PSI, i guess the reason i really want to know is in case having that much could possibly be damaging the bike.

[Terry in Australia]

5-10 PSI is right for aftermarket caps, as your forks compress (when you sit on it, when you go over a bump, when you brake etc) the air pressure in the forks is increased by multiples of whatever you put in it, so for instance, if you had 35 PSI in it (and I'm surprised that your fork seals haven't popped, by the way) and you compressed the forks by 20% of their overall internal volume, then you have increased your air pressure to upwards of 40 psi.

Those sorts of pressures keep your tires as near as dammit to rigid, so while your compression damping is horribly hard, your rebound damping as the same as it always was, so you'll end up with a very hard pogo stick, instead of a more predictable set of shock absorbers. Drop some air out mate, before it spits you off, those roads are very abrasive! Cheers, Terry.    

[78_SaltLick]

So can you drop air out of it just like a tire? Basically stick a key or something in there, and let out the pressure? So you guys think maybe half of that like around 15 PSI or something?

[Philly550K1]

Excellent replies.  MC Enterprises.  That's the name.

Without increasing rebound damping, what is/was the alleged benefit?  Would it be like raising your tire pressure but keeping the same contact patch?

[mick750F]

So can you drop air out of it just like a tire? Basically stick a key or something in there, and let out the pressure? So you guys think maybe half of that like around 15 PSI or something?

   Hey Salty read our lips...5-10 PSI

Mike

[cb650]

They might hold at 35 but a big jolt could blow them out.   Only customs and nitehawk 650s had air assist stock.



                                  Terry