How pair system works precisely ?
 

Looking at the service manual, I was surprised !
I was thinking pair system works when deccelerating and that's why we here exhaust popping at deceleration...
But "the pair control valve cuts off supply of fresh air during engine deceleration, thereby preventing afterburn in the exhaust system" as the service manual says.

looking one time more at the service manual, the pair system is flowing fresh air almost all the time, it cuts only at deceleration (high intake vacuum) to eliminate afterburns.
Then, here are some questions :
- Why is there a popping effect at deceleration with pair system enable ? Maybe, the hoses connected to headers have enough fresh air to deliver during a little time and cause afterburns ? or pair valve is not very quick ?
Or it is because of downshifting that leaves the engine to take revs ?
- What are the effects on a dyno gaz analysis with a pair system enabled ? The carburation may always seems to be "lean", isn't it ?

Anyway, I think I will disable this pair system this week end ! ;) and redo a carbs sync by the way

Re: How pair system works precisely ?
 

Maybe in theory... Maybe not in practice.
Bear in mind that this is a system born of the need to reduce emissions, not increase performance. I removed mine... also re-routed my crankcase breathers to external filters instead of to the airbox. May not make more HP :?: , but it seems to make more sense.

also be aware that honda techs did tune this bike to run WITH the pair system. it does greatly reduce emissions, i can tell you that for sure. the only way i can see it robbing power is if you have a claifornia model....

By injecting air in to the exhaust stream, it probably does have some small detrimental effect on scavenging of the cylinders which helps draw in a fresh intake charge. So would have some effect on power, especially at the top end. Probably very small. My heads have aluminum plugs bonded in and ground flush with the ports, never to be imPAIRed again!

I have left the crankcase breathers routed to the airbox to clear the blowby gases from the crankcase and keep them from coating everything with black goop.

Re: How pair system works precisely ?
 

pair system disabled :wink: