Breather or not
Thread Starter
Member
Squid
Joined: Jan 2010
Posts: 60
Breather or not
I have a 98 SH with 34,000 just bought it about a month ago, I have read losts of posts in here and even came across someone saying not to plug the crankcase. Well when I got the bike It had two bolts one on the rear cylinder and one on front cylinder. I have since replaced the bolts with crankcase breathers directly connected to valve cover. its a breather from auto parts store. My question is should I leave it with breather or put bolts back in?
Senior Member
Superstock
Joined: May 2008
Posts: 347
From: S.Dak USA
Not exactly sure what bolts/breathers you are talking about.There are breathers in the valve covers that are part of the PAIR system.This is for emissions. Some people just disable them,some remove the system completely.If you look for the sticky "Pair removal" in the knowledge base should tell you all you need to know. I have disabled mine to help stop the "popping" on overun in my aftermarket pipes.There may be a slight performance increase with disabling them,but I can't feel the difference.
Thread Starter
Member
Squid
Joined: Jan 2010
Posts: 60
Breather or not
Not exactly sure what bolts/breathers you are talking about.There are breathers in the valve covers that are part of the PAIR system.This is for emissions. Some people just disable them,some remove the system completely.If you look for the sticky "Pair removal" in the knowledge base should tell you all you need to know. I have disabled mine to help stop the "popping" on overun in my aftermarket pipes.There may be a slight performance increase with disabling them,but I can't feel the difference.
Senior Member
SuperBike
Joined: Mar 2007
Posts: 1,611
From: Belgium, WI
The pair system can be plugged, but the breather system should not be. If the portion that is plugged of which you speak is connected to the aluminum colored piece that is bolted to the valve covers, play through.
Squid Poacher
Back Marker
Joined: Oct 2009
Posts: 116
From: Orange Park, Fl.
Thread Starter
Member
Squid
Joined: Jan 2010
Posts: 60
Senior Member
SuperBike
Joined: Aug 2004
Posts: 1,806
From: Atlanta, GA
No. That is what remains of the pair system. You can plug that with no worries. It doesn't need to breathe. It is not part of the crankcase ventilation, which are the larger hoses that go from the crankcase into the airbox.
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SuperSport
SuperSport
Joined: Dec 2006
Posts: 880
From: Victoriaville, Quebec, Canada
The crankcase vents are bigger than the pair hoses, what you put breathers onto are the PAIR reed valve covers, you should plug these and save the breathers for another use.
Plugging breathers will result in gaskets damage, poor mileage, on a V-twin, both cylinders are going down close to each other, the air need to rush out and back in. On an I-4 two up while 2 down, the breather is mostly to get the blow by and oil vapors out.
Plugging breathers will result in gaskets damage, poor mileage, on a V-twin, both cylinders are going down close to each other, the air need to rush out and back in. On an I-4 two up while 2 down, the breather is mostly to get the blow by and oil vapors out.
Thread Starter
Member
Squid
Joined: Jan 2010
Posts: 60
Breather or not
Cool Killer thanks. When I got the bike I was like what the heck the crankcase is not breathing. So that is part of the pair system. Cool. I went outside and I see that there are larger hoses going to the underside of air box.
Senior Member
SuperBike
Joined: Mar 2007
Posts: 1,611
From: Belgium, WI
Just had a stunning idea. On some high performance vehicles they run vacuum pumps on the crankcase. You could run a hose from the breathers to the pair system and build more HP with some low tension rings. Done and done.
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