CLASS system operation and pressure

[Brenner]

I was looking over my project today and turned the key on to ACC and as the CLASS system functioned a question or thought came to mind. I did not know the answer so I looked into my manuals and see no spec or reference to my question so I thought I would ask here and maybe someone with experience or knowledge might be able to answer or assist me. My question is that my CLASS does work as stipulated in the service manual but I was wondering if the system should hold residual pressure in its off state and if so is there a time spec in which a loss rate could apply? Meaning I operate my CLASS it pressures up and I can leave it there for a while and it will not drop in pressure to kick the compressor in but I think it is not holding pressure over night. I will have to verify to be sure but I am unsure if the system is designed to do this or does it release pressure when off and need be set each time I choose to ride ? My owners manual or service manual does not stipulate anything in regards to this. Any one please, how does your system work and should I be looking for a problem?

[Peder_y2k]

On my 88, the pressure in the rear system holds steady for weeks. It loses some pressure simply turning it on to check pressure. My bike has the Progressive Springs in front and needs no air pressure help.

Pete, in Tacoma WA USA

[Marcarl]

It should hold the set pressure. You will loose pressure as you check for pressure as mentioned, but this will be very little, but then very little means quite a bit in such a small system. It will not air back up on it's own, you need to do that. So if you notice a loss, you need to physically get it to pump back up again. If you are losing air overnight, there is a small leak,,,,, very small. Most likely in the valves that control the airflow.

[MiCarl]

Once the CLASS reaches the pressure it's looking for it basically shuts down. You can leave the key on, but if there is a leak the CLASS won't kick back in until you press buttons.

 

Theoretically it should never leak down. Like Peder I have different springs in front and never pressurize them. The rear holds well enough I don't notice any change until I change the pressure setting (passenger or not), except for maybe a few PSI over winter. Remember though that temperature, weight on the bike and whether it's on the center stand or not will affect the reading. Also like Peder mine discharges a little spurt from the valve any time I select the Front or Rear button.

 

I'd suggest you put it on the center stand, set a pressure and remember it. After a few days put it back on the center stand and re-check it. If you're down more than a couple PSI you should look into it.

[Brenner]

It should hold the set pressure. You will loose pressure as you check for pressure as mentioned, but this will be very little, but then very little means quite a bit in such a small system. It will not air back up on it's own, you need to do that. So if you notice a loss, you need to physically get it to pump back up again. If you are losing air overnight, there is a small leak,,,,, very small. Most likely in the valves that control the airflow.

 

Isolated to the valves by means of a soap test. Lost .4 in 3 hours and small bubbles coming from dryer case. I guess I will pull it apart tomorrow as both front and rear have lost the same amount of pressure. I am running progressive springs in the front but the rear is where it concerns me. I would like this to work correctly as I went to this bike to be able to ride 2 up and pull a trailer. The hitch is on and waiting. Guess I should be happy that I am working through the small stuff now rather than when it goes on the road next month. Thank you to all who replied as it helped knowing what the system is supposed to function like and made it easier to understand and diagnose one of many problems I am working through. I am slowly winning the fight with this project. Thanks again.

[Marcarl]

So now your going to pull that apart eh???? Some points then to help you along.

Clean all connections and don't put dielectric grease on them, but you could spry them with Fluid-Film when they are back together, good stuff that!! Open up the dryer and carefully remove the silica gel that is used as a dryer material. Put the gel in a ceramic dish and nuke it for about 2 minutes,,, now it's dry to use again. Take off the exhaust rubber tubing, split the filter easy to come apart) and make sure that is all clean. Take the valves apart,,, be very careful, the springs in there are small, light and have a habit of taking a road of their own. So be careful!!!!! Check the inside of the valves, especially the seats, they can corrode a little, if they are, just use a small drill bit with some fine steel wool attached to the end to hone them clean. use air to clean and then reassemble, use no lubricant.