All 650's PAIR VALVE REMOVAL (improved version)

Frances77 · Oct 8, 2023

I've been trying to find the bolts that hold the funnels to the air box/throttle body online. I can't find them, anyone know what they are called or where I can get them? Thanks.

Brammers · Oct 8, 2023

Fowlers have them, I ordered a set after I stripped the heads from not using JIS drivers.

Number 17 on here https://www.fowlersparts.co.uk/parts/6577534/cb650fa/air-cleaner

J

Frances77 · Oct 8, 2023

Brammers said:
Fowlers have them, I ordered a set after I stripped the heads from not using JIS drivers.

Number 17 on here https://www.fowlersparts.co.uk/parts/6577534/cb650fa/air-cleaner

J

Thank you again👍

Dan1001 · Oct 13, 2023

Hi guys and girls. Sorry for post on this thread. I think I got the noise pair valve. So my bike sounds sweet as a nut on warm up. Get it up to temp. When off the throttle pulling up to lights or round abouts it sounds like I have a bearing gone. I wouldn't say it's a ticking sounds. It will then continue to be noisy until I crack it open again to pull away.
Sound like pair valve??

Cláudio Nogueira · Oct 13, 2023

Dan1001 said:
Hi guys and girls. Sorry for post on this thread. I think I got the noise pair valve. So my bike sounds sweet as a nut on warm up. Get it up to temp. When off the throttle pulling up to lights or round abouts it sounds like I have a bearing gone. I wouldn't say it's a ticking sounds. It will then continue to be noisy until I crack it open again to pull away.
Sound like pair valve??

Hmmm! I bet no one can ear PAIR reed valves with the helmet on, even less, with the bike running!
Leave the PAIR valves alone. They, alone, don´t represent any kind of performance loss, just a huge emissions reduction.

Brammers · Oct 13, 2023

I could hear them while doing 40mph! Roll off the throttle at 4k rpm and bam...tick tick tick.

J

Cláudio Nogueira · Oct 13, 2023

Brammers said:
I could hear them while doing 40mph! Roll off the throttle at 4k rpm and bam...tick tick tick.

J

Yes, then my apologies, I must admit mine don´t do that kind of noise because I must pay close attention to ear them, even when I'm standing by the bike. Looks like what you are discussing here is something I never experienced... thankfully.
Sorry for not adding nothing valuable...

Arthur45 · Oct 13, 2023

Dan1001 said:
Hi guys and girls. Sorry for post on this thread. I think I got the noise pair valve. So my bike sounds sweet as a nut on warm up. Get it up to temp. When off the throttle pulling up to lights or round abouts it sounds like I have a bearing gone. I wouldn't say it's a ticking sounds. It will then continue to be noisy until I crack it open again to pull away.
Sound like pair valve??

Hi. If this helps in my opinion the CB650 does have a distinctive noise on idle, off throttle with low revs etc. Again I think always pair valve related if the bike is stock. I think it's one of those things that you either just try to tune it out of your ears, or remove them. The pair valves....not ears of course 🤣 . The noise still bugs me, but as it helps with emissions, I'm happy to leave them in. Think some have mentioned throttle and running is better without them.......

There's a few videos on the forum so you may want to compare bikes idling to yours...just an idea.

Brammers · Oct 13, 2023

@Dan1001 if you're anywhere near north Hampshire, let me know... I'll take a listen for you.

J

Dan1001 · Oct 13, 2023

Brammers said:
@Dan1001 if you're anywhere near north Hampshire, let me know... I'll take a listen for you.

J

That would be great as I dont hear any kind of ticking just like a rolling bearing noise. So I'm just outside Swindon so not far.

Arthur45 said:
Hi. If this helps in my opinion the CB650 does have a distinctive noise on idle, off throttle with low revs etc. Again I think always pair valve related if the bike is stock. I think it's one of those things that you either just try to tune it out of your ears, or remove them. The pair valves....not ears of course 🤣 . The noise still bugs me, but as it helps with emissions, I'm happy to leave them in. Think some have mentioned throttle and running is better without them.......

There's a few videos on the forum so you may want to compare bikes idling to yours...just an idea.

So little bit of background info. The bike did have an akra race system on it. Was to loud for my poor little one at 5am each morning.

I've gone back to stock system and now it feels like when off throttle it's makes a horrible noise and the engine breaking is so harsh on it now.

Brammers · Oct 13, 2023

Might be exhaust leak at the headers. Often sounds like ticking.

Did you use new gaskets? (we should probably take this to a new thread).

J

Arthur45 · Oct 13, 2023

Dan1001 said:
That would be great as I dont hear any kind of ticking just like a rolling bearing noise. So I'm just outside Swindon so not far.

So little bit of background info. The bike did have an akra race system on it. Was to loud for my poor little one at 5am each morning.

I've gone back to stock system and now it feels like when off throttle it's makes a horrible noise and the engine breaking is so harsh on it now.

All noted.......I've described mine as sounding like a 'bag of spanners' against my previous CBR600F.......

Dan1001 · Nov 7, 2023

Hello again. Managed to do the PAIR removal today. Every issue I had with the bike is gone. Sounds normal and throttle is 100 times better. Still running stock pipe so will change that soon, or if cat will be ok keep may keep it on, My only issue is now I'm getting a weird sound from the filler cap. Sounds like my bike is snoring, any ideas? As soon as I open the cap it goes.

JRinKtown · Nov 7, 2023

Dan1001 said:
Hello again. Managed to do the PAIR removal today. Every issue I had with the bike is gone. Sounds normal and throttle is 100 times better. Still running stock pipe so will change that soon, or if cat will be ok keep may keep it on, My only issue is now I'm getting a weird sound from the filler cap. Sounds like my bike is snoring, any ideas? As soon as I open the cap it goes.

Maybe you pinched the tank breather hose when you did the work. Sounds like the tank is having a hard time pulling air in as the gas goes down. That the issue vanishes when you open the cap would confirm that.

Dan1001 · Nov 7, 2023

JRinKtown said:
Maybe you pinched the tank breather hose when you did the work. Sounds like the tank is having a hard time pulling air in as the gas goes down. That the issue vanishes when you open the cap would confirm that.

I've lifted the tank and the hoses are free. I'll check again though. If that was the case wouldn't it create a Vacum and struggle to pull fuel and run?

miweber929 · Nov 7, 2023

Dan1001 said:
If that was the case wouldn't it create a Vacuum and struggle to pull fuel and run?

Not right away. Also depends on how much the vent is plugged

Cláudio Nogueira · Nov 8, 2023

Dan1001 said:
Hello again. Managed to do the PAIR removal today. Every issue I had with the bike is gone. Sounds normal and throttle is 100 times better. Still running stock pipe so will change that soon, or if cat will be ok keep may keep it on, My only issue is now I'm getting a weird sound from the filler cap. Sounds like my bike is snoring, any ideas? As soon as I open the cap it goes.

Hello.

Removing a system that injects clean air in the exaust improved you throttle response?! I doubt it! Removing PAIR does nothing in terms of performace. All you get is increased emissions as you loose the opportunity to promote unburnt fuel to get burnt in the cat.

My tank also does that, because the vent is not open to the outside. It is connected the a circuit that manages gas delivery to a carcoal canister.
If your bike has no carcoal canister, I believe the vent tube should release that pressure.

Dan1001 · Nov 8, 2023

Cláudio Nogueira said:
Hello.

Removing a system that injects clean air in the exaust improved you throttle response?! I doubt it! Removing PAIR does nothing in terms of performace. All you get is increased emissions as you loose the opportunity to promote unburnt fuel to get burnt in the cat.

My tank also does that, because the vent is not open to the outside. It is connected the a circuit that manages gas delivery to a carcoal canister.
If your bike has no carcoal canister, I believe the vent tube should release that pressure.

Sorry should of been more clear, I've not gained any proformance from removing the PAIR valve. My throttle response just feels so much better, also so does the engine braking. Doesn't feel as strong off throttle.
My plan is to remove the cat.

That's strange. I'll take the tank off again and have a look to see everything is still connected ok. Only noticed it after removing my tank.

Mr.D · Nov 4, 2024

If you prefer cheaper parts you might order the block off plates from china

https://pl.aliexpress.com/item/1005005857589827.html?gatewayAdapt=glo2pol

Mr.D · Jan 4, 2026

For anybody wondering what resistor you should use while doing this, I soldered inline two small resistors that together make 24.6 ohms and it work without a problem.