View Full Version : anti-return valve

09-18-2004, 10:11 AM
Over the last month and a half I've been having issues on and off with my bike. One day it would run great the next it would run like shit. Mainly stalling problems. Not just stutters but major stalls. I'd twist the throttle and the bike would decelerate versus accelerate like it was being strangled.

It got so bad that I disconnected the PCIII hoping that was the problem. It ran great after a while then the stalling came back with a vengeance. It got worse.

Took it back to the dealer and they were stymied. Which was not a good sign. I told them to call Clarkie which they did. They disconnected the battery and let it sit for half a day before reconnecting. Re-loaded map 2, hopefully the right way. Balanced the screws on the throttle bodies.

The tech said it's still running too rich. So he looked into the anti return valve in the slipper clutch. That's a new one, I've not hear or read about it on this board. He said mine isn't working properly afer he checked it and he thinks that might be the culprit. He ordered the part and still waiting for it.

What the heck does a clutch have to do with my stalling issues? Any opinions?

09-18-2004, 10:50 AM
I'm definitely not an expert, but I thought I'd heard that our bikes have some type of vacuum assisted clutch. If vacuum is not being manged properly, of course that can play havoc with the motor. It's the motor that generates the vacuum, and the vacuum give the motor the air it needs to ignite the gas the injectors feed it. And with today's electro-assisted crap, who knows what mixed signals and compensating is going on.

When stuff like this hits me, I'd take off the body work and stare it it for awhile with a cup of strong coffee. Often I can see an anomoly. I look first at anything I've messed with.

RZ Rob

09-18-2004, 04:46 PM
Just to illustrate the clutch throttle body connection: Pop the tank and remove the lid from your air box (or not if you have modded the AB) then pump your clutch in and out a few times you'll hear it working. Your dealer could be on to something.

Let us know what happens.

Good luck.

09-25-2004, 09:04 PM
Well it turns out this vacuum / anti - return valve is the culprit!!! The part finally came and my dealer replaced it. Took the bike out for an all day ride today and it was flawless! No more bogs or stalling. Even the clutch is working properly again.

Good to finally have my bike working properly. :D

If this hadn't worked I was about ready to get my dealer to give me a brand new one.

09-25-2004, 09:34 PM
errrr ok...................:confused:

i am glad your bike is fixed Arnie, but a faulty check valve wont cause that unless it has a hole in the side of it.

did they (or anyoen else) remove the CA emmissions stuff when they prepped the bike?

i had an 03 bike that had one of the block-off plugs fall out from the blocked off CA emmissions and it did something similar.

i guess i will have to put the price of our check valves up again :)

09-26-2004, 08:11 AM
Incidentally I did ask about the CA emissions. As usual the tech was clueless, he just gave me this blank expression. Which by the way I'm getting quite used to now since I've been there so much lately and every time I ask him to check something I get the same expression. Truly sad, lucky for him I have a pretty good sense of humor otherwise I would have been arrested for assault with a blunt object by now.

Anyway, back to the topic at hand. Tim had to order this bike for me. He didn't have a Silver Factory in stock at the time. There's a 50-50 chance they didn't prep it. Where would I find the block off plug for the CA emissions so I can check if it's there or not.

BTW, the CO levels are still pretty high, like 7%. I know 2-4% is optimal. Again the tech can't figure out how to lower them. Clarkie he followed your instructions and Richard at Aprilia gave him the same. Still no go. Do you think a PCIII with a custom map will help smooth that out?