[ KB ] PAIR System Removal
 

Category: VTR1000F Modifications
Type: How-To

Article Name: PAIR System Removal
Author: mamisano
Description: How-To Remove The PAIR Emissions Equipment

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I can speak from experience when I say a malfunctioning pair valve will destroy exhaust valves and seats.

If your bike backfires under engine breaking or rev-down its probably a malfunctioning pair valve system.

If you can, disable it. If you can't, make sure the valve closes under vacuum and all the hoses are good.

How does a malfunctioning pair valve destroy an exhaust valve?
If the (oneway) reed valve broke, and it stayed open all the time, hot exhaust gas would just cook the air supply hose leading to the valve.
then it would give you an exhaust leak and lots of back firing.
Don't see why it would burn a valve though.

~Jeffers

Thats not usually how they break. What usually happens is the vacuum line that closes the air supply valve under vacuum cracks and leaks and never closes off the air supply to the pair valve. I've never seen reed valve damage.

When air is allowed to enter under engine breaking it creates powerful backfires that pulverize the exhaust valves and seats.

Other than pounding and scortching the valves and seats, it also can build a carbon film on one side of the valve seat and over time the exhaust valve bends to match the irregular seat.