All 650's PAIR Valve Removal

[aaronlukemarshall]

Updating from old site as a few people have enquiries about the mod:

Reasons For:

Throttle is buttery smooth all the way up and down the line in all gears. No garbled noises or stutters on deceleration just smooth linear transitions.

Approx 6 hours maximum to complete.

It's a simple mod in theory but I wouldn't say it for beginners or non mechanically minded people there's a few things that can go horribly wrong if your not careful

You can order them from eBay for £25-$30 ish.

http://m.ebay.co.uk/itm/252363217562?_mwBanner=1

Follow the Service manual to take out the air box.

Once they arrive you need to fit them in tight this will mark then aluminium plates with the screw marking.

You'll need to use a 12mm drill bit and drill down 2-3 mm for screw clearance.
Use wet and dry paper to clean off sharp edges use P320 paper or better.


•Plates after drilling

To check they seal is ok wipe a light oil in the plate surface press the reed valve and rubber seal into the plate on both sides you should see a oil ring appear where there is a good seal. This means you'll achieve the correct engine seal when mounting on.

•Oil Seal Marking on Plate


•Reed Valves with Seals


•Blanking Plates fitted.


•Blanking plates underneath airbox.



•Airbox Blanking Cap.


•1Kg of Gubbins Removed.

Follow the service manual and replace everything back to how you started.

For *completeness you can add a 27ohm Resistor 10w thin film to complete the circuit however it's not monitored by the bikes ECU so doesn't affected daily riding or error messages.
*I have OCD so I needed to completed the loop.

•27Ohm Resistor (Optional)

Secure with zip tie and use amalgamation tape to finish off.

•Resistor Tied on.

 

[Brammers]

I skipped the resistor part with no ill affects.

Also I went a different route and removed the screws instead of drilling the plates.

This does destroy the reeds valves though, needing new ones to revert to stock.

Everything else Aaron says is spot on.

J

 

[Alienspy]

Cool. Any check engine lights after? What kind of feedback are you guys getting as far as throttle response?

 

[aaronlukemarshall]

Cool. Any check engine lights after? What kind of feedback are you guys getting as far as throttle response?

Please read the post your questions are already awnsered

 

[Brammers]

Throttle response is improved.

The bike doesn't sound like a bag of bolts when idling either.

J

 

[Alienspy]

Please read the post your questions are already awnsered

Sorry, I had to check it on my phone. The work computer doesn't allow ebay links.

 

[aaronlukemarshall]

Sorry, I had to check it on my phone. The work computer doesn't allow ebay links.

Fair play. Everything at low speeds is much better.

 

[Alienspy]

Are you running a full exhaust , and did you have to remap your pc5?

 

[Duncan]

To cover off the use of the PAIR valve, as we understand them.

• it "injects" air into the exhaust flow. this happens from the low pressure behind the exhaust gas pulse.
• The extra oxygen is used to heat the O2 sensor and the Cat'Converter to operating temp. In the EURO4 market, start up is the most critical part of the bike non-compliance period.
• The valve is set to be open on no current, thus no error code and no real need for the resistor. only when the throttle is opened should the valve close.

• If you remove the cat converter, you remove most of the need for O2 "injection" altogether. except for the O2 system being a bit out for a few minutes till up to temp.

• there is an anecdotal issue with a slight lag in getting on the throttle when cold, which suggest PAIR & ECM are not always on the same page below 5000rpm. the OP reports that some related issues getting cross port scavenging working reopening throttle are improved.

Thanks for putting the OP together Aaron.

 

[Brammers]

Full exhaust here, no remap or pc5 (yet).

Duncan is right about the warm up... It idles a little rough from cold for a minute or so, then settles down nicely once temps come up.

J

 

[aaronlukemarshall]

Are you running a full exhaust , and did you have to remap your pc5?

Doesn't need a PC5 for the mod. And didn't need a remap.
It purely changes the throttle feel and jerkiness at low speeds.

 

[Brammers]

And I don't understand why it changes anything... As it's all exhaust side.

But it does.

J

 

[Duncan]

the effect of the exhaust, through scavenging, can help draw air/fuel charge into the combustion chamber.
the pair valve disrupts scavenging, particularly when you just crack the throttle. Its effects are not just on the exhaust side.

it also plays silly games with the O2 sensor, but the correction sampling seems slow to react.

 

[Brammers]

Thanks, most enlightening!

J

 

[GPJake]

Awesome topic & info. Though that is far, far deeper into the bike than I ever trust myself getting.

 

[aaronlukemarshall]

Awesome topic & info. Though that is far, far deeper into the bike than I ever trust myself getting.

It's the only way to learn.

 

[GPJake]

It's the only way to learn.

Agree with you on that.

For now I'm sticking to the minibike and go kart with the kids

I do the smaller stuff... Oil/etc.. Baby steps .

 

[Duncan]

Awesome topic & info. Though that is far, far deeper into the bike than I ever trust myself getting.

if you have replaced your air filter, or lifted the tank, the pair valve is just under the air box. about 4 more screws. Then you will see what is in the picture tagged "•Blanking plates underneath airbox."
it's also where you get to to replace the spark plugs.

 

[aaronlukemarshall]

if you have replaced your air filter, or lifted the tank, the pair valve is just under the air box. about 4 more screws. Then you will see what is in the picture tagged "•Blanking plates underneath airbox."
it's also where you get to to replace the spark plugs.

4=6 ;-)

 

[Jonathan]

Excuse my ignorance but what is a pair valve and why is it there ifor not essential?