Breather Hose Fix

[Shipper]

1975 650B with one breather hole plugged with the OEM holed rubber stopper and the other hole open. I believe it came stock that way. Further, no hose nipples on the air boxes and no drain hole in the left engine cover for chain lube solution means; installation of power brake check valve to a Mikes breather filter as a solution. One question, should I use one power brake check valve on the unplugged side prior to the t joint to the filter or one pbcv on each side prior to the t joint to the filter?

Comments?

 

[5twins]

You shouldn't need a filter after the check valve because air only flows out. I think the original set-up on a '75 had one breather nipple completely plugged, the other completely open. There was only one hose, on the open side .....

http://www.boats.net/parts/search/Y...CYLINDER HEAD COVER TX650A - XS650/parts.html

That rubber reducer plug I think came from a later model. They had them in each outlet nipple and ran 2 hoses, one to each airbox. None of the parts diagrams I've seen show them. All I can figure is they came as part of the breather box, pressed in at the factory. Kinda like the 5/16" ball in the clutch worm gear, part of that "assembly" so not shown separately.

 

[Shipper]

You shouldn't need a filter after the check valve because air only flows out. I think the original set-up on a '75 had one breather nipple completely plugged, the other completely open. There was only one hose, on the open side .....

http://www.boats.net/parts/search/Yamaha/Motorcycle/1974/TX650A/CYLINDER HEAD - CYLINDER HEAD COVER TX650A - XS650/parts.html

That rubber reducer plug I think came from a later model. They had them in each outlet nipple and ran 2 hoses, one to each airbox. None of the parts diagrams I've seen show them. All I can figure is they came as part of the breather box, pressed in at the factory. Kinda like the 5/16" ball in the clutch worm gear, part of that "assembly" so not shown separately.

Hey Twins - good to talk again. Thanks for your advice. Couple of things;
1. I am told that the filter after the check valve will catch any oil puke from the right side breather? (left side with reducer plug just blows light mist.)
2. Is it feasible to insert a reducer plug in the right side breather nipple and thereby limit oil puke?

Thanks for any comments to the above.

Shipper

 

[David Toll]

Hello Shipper. As 5T says above, it would appear that the originals had a reducer plug in both outlets. I hope so 'cause my '78 only had one when I bought it so I ground down a piece of fuel line to make one for the missing side. Rebuild isn't finished yet but I assume it will run right. I used fuel line because the internal hole diameter was the same as the original. Some later models had reducers cast into both outlets tubes I believe.

 

[5twins]

Actually, later models switched to a single outlet casting with the hole size reduced .....

You can swap this later unit onto yours if you like. Yes, if you have 2 outlets and are going to run 2 hoses, use 2 reducers. When I first got mine running, I followed some internet advice that said you didn't need the reducers. I ran both my hoses to a "T" fitting, then down to a K&N breather filter. The K&N was always wet with oil, not to the point of dripping it out, but always wet. I was letting too much oil and oil vapor out in my opinion. I put the reducers back in.

 

[Shipper]

Actually, later models switched to a single outlet casting with the hole size reduced .....

You can swap this later unit onto yours if you like. Yes, if you have 2 outlets and are going to run 2 hoses, use 2 reducers. When I first got mine running, I followed some internet advice that said you didn't need the reducers. I ran both my hoses to a "T" fitting, then down to a K&N breather filter. The K&N was always wet with oil, not to the point of dripping it out, but always wet. I was letting too much oil and oil vapor out in my opinion. I put the reducers back in.

Thanks Twins & DT,

I found a pair of original air boxes (breather nipples on both sides) on e-bay for a really good price. So my first fix attempt will be to swap out my no-nipple air boxes with the new ones purchased on e-bay. Failing a successful fix, I will block "both" outlets with reducers to the new air boxes. If that doesnt get me where we need to be regarding oil bypass, I'll start looking for the breather cap with just one air nipple and run the brake check valve off it and go with that.

Thanks for the info guys. Much appreciated.

Shipper

 

[5twins]

You want reducers in both outlets no matter what they run to. Too much oil and mist will come out otherwise. Your first "fix" will gunk your carbs all up with oil. I guess I can see the need for open breathers on a race motor maybe, but for the street it just makes a mess.

If you eventually do look for the newer single outlet housing, try to find a complete unit that includes the little tin baffle plate inside. I don't think the baffle plate from your current 2 pipe unit will swap.

 

[Shipper]

You want reducers in both outlets no matter what they run to. Too much oil and mist will come out otherwise. Your first "fix" will gunk your carbs all up with oil. I guess I can see the need for open breathers on a race motor maybe, but for the street it just makes a mess.

If you eventually do look for the newer single outlet housing, try to find a complete unit that includes the little tin baffle plate inside. I don't think the baffle plate from your current 2 pipe unit will swap.

Thanks 5Ts, what would you use to make that second baffle? And, I have had the tin plate etc apart - can you force a self made baffle plug into that small channel properly? Your suggestion on the second plug is where I want to go with the proper air boxes.

Any suggestions on my front calliper issue?

 

[5twins]

Maybe a rubber stopper with a hole drilled in it? Or maybe some rubber hose if you could find just the right size. There's something else you should investigate. To help solve this excess oil spewing problem, besides adding reducers Yamaha also reduced the amount of oil used in the motor. This change happened sometime in 1975 so it's possible you have an early one that didn't get it. Here's a tech bulletin with details .....

As far as your caliper goes, I don't know. It's new, it should work fine. But considering where it came from, I guess we know that's not always the case. I suppose I would pull it all apart and check all the fluid passageways are clear. Maybe there's casting flash or something partially plugging the ones for that inner pad.

 

[Shipper]

Maybe a rubber stopper with a hole drilled in it? Or maybe some rubber hose if you could find just the right size. There's something else you should investigate. To help solve this excess oil spewing problem, besides adding reducers Yamaha also reduced the amount of oil used in the motor. This change happened sometime in 1975 so it's possible you have an early one that didn't get it. Here's a tech bulletin with details .....

As far as your caliper goes, I don't know. It's new, it should work fine. But considering where it came from, I guess we know that's not always the case. I suppose I would pull it all apart and check all the fluid passageways are clear. Maybe there's casting flash or something partially plugging the ones for that inner pad.

Really good info Twins. I am a ser # after 103 and it does looks like I am carrying too much oil. I will look to fashion an appropriate stopper for the right side nipple and lower the oil level according to the bulletin. Really would like some dimensions for a new stopper but if it ain't out there than I go it alone.

As far as the calliper goes, it's looking like a tear down of the front brake system (again) and starting over.

Thanks again Twins, really helpful.