Does anyone know what the air suction valve does or how to tell if its working properly?

 

Air suction valve????

Are you refering to the thing in the airbox that has a filter on it (about the size of a pinkie finger)???? If so, it provides vacume to the "pair control valve" on the carb. (Don't ask me what a pair control valve is!)

It has something to do with meeting emissions standards.......and I thought it only came on California models????????

 

I'm talking about the pair control valve. In the parts manual its called a air suction valve, must be the same thing though. Does your 90 have one on it? The reason I'm asking is I'm having trouble with the Idle on my daughters 2002 trx90. I have been through the carb twice completely making sure it was clean. I havent replaced any jets or needles (all looked ok to me). Nothing has fixed the problem so i was wondering about the pair control valve. I took the one on my daughters apart this morning. It looks like diaphram that is operated by the vacuum line from the intake. any ideas?

 

I had asked about this valve severaly times in the past, and absolutely nobody (even Californians) seemed to know what I was talking about. I got the impression that it only came on Calif. models, so I am surprised that you have it on one from NC.

All my quads came down with idleing problems, all at once. Turned out to be a batch of dirty gas. I would clean the carb, and it just didn't help until I drained all the tanks and started out with fresh clean fuel.

 

I appreciate your help. I drained the tank the last time i cleaned the carb and it did help but i put the same gas back in it. maybe ill drain it again and put new gas in. Do you know if they make a carb kit for a 2002?