What do block off plates do on a motorcycle?

Are you finding the use of block off plates a mystery? Should you do this modification, and will it make your motorcycle perform better?

Block off plates are a simple way to reduce emissions on your motorcycle. They prevent induced air from entering the airbox, which results in cleaner emissions. A DIY modification is not for everyone and can be time-consuming and costly if taken to a mechanic.

What is an engine block off plate?

It replaces the pulsed air secondary induced air system, or in better words, discards this complicated PAIR valve that can cause problems.

The Pair valve is part of your exhaust emission control system. It can be pretty technical and a boring subject to cover. However, I will do my best to explain the ups and downs of block off plates.

Why get rid of the PAIR valve? Well, there are many reasons, they can be temperamental, and as soon as you modify your motorcycle or tune for performance, the PAIR valve will be out of whack and your emissions all over the place.

You can spot a bike that has been tuned for performance with a PAIR system in place, it pops and burbs as the system struggles to deal with anything other than stock tuning.

Block off plates do exactly what they say. They block off the ports where the PAIR system used to be located.

Do block off plates improve performance?

The only successful way to improve performance on a stock motorcycle is to remove the PAIR system and block off plates.

Block off plates will allow you to tune your bike for maximum performance. You will notice increased acceleration and general engine performance.

If you are a severe rider, then block off plates are a no brainer to get the best performance from your engine.

If there is a downside, you will likely have a continuous check light on the instrument cluster. To remove this, you may need to flash the ECU.

Is a block off plate bad for your Turbo?

With most bikes not fitted with turbo, the question is redundant, but a turbo would be affected by block off plates. You will find the turbo hunting for air and maybe fluttering a little and chuffing.

Turbo performance would be reduced with the use of blocking plates.

What do block off plates do on an R6?

If you are tuning your Yamaha R6, you will need to use block off plates to get the best from your engine and, more importantly, an accurate fuel map. 

If you tune without fitting the block off plates, you may not have enough volume and fuel pressure for the bike to run smoothly; hence the popping can crack on deceleration.

For some of you, popping and cracking on deceleration may seem like an excellent addition to your R6 so, if you are after some cool noises, leave the PAIR in place.