Head Breather

[Wally]

The 80s XS Special head breather pipe
Will drilling out this breather make any difference Im told to drill it out with a 9 mm drill & put more holes in the baffle plate inside the breather????????
Ref No 14,16

 

[inxs]

- you have this?

- bertaut suggests opening these out, however as the XS has evolved the breather has gone from the larger double outlet to the smaller more restricted single outlet

- although it could be useful doing this for larger displacement motors as a means to prevent the seals from popping i assume yamaha engineers had a good reason for the restrictions apart from emission regulations

 

[xsjohn]

Opening the breather on the single spigot.........will make more air going in and out which brings more oil out.........been there and done that........could use a one way breather valve like many have including myself..........creating negitave pressure in the crankcase........without opening the breather hole...........

xsjohn

 

[Wally]

I have the top one in pics
I have since rebuilding this engine some two years ago have not been able to resolve leaks from cam cover seals & yes I have done all the Suggested Investergation & repairs.
Taken head of & centre cam. replaced seals,gaskets & O rings to many times to remember, changed cam as well with all new seals & caskets put larger spring on cam seals.

Now have run bike with breather hooked up to air box, seal leaks
Disconnect breather tube from air box, dont seem to leak, Jury still out.

So I will drill it out & run a line down to ground as in the old girl way & seal oir box breather holes & see what happens next see

 

[inxs]

- before drilling everything out you may like to try using a brake booster check valve in the breather line, creates a negative pressure in the crankcase which has the effect of sucking the seals into the case and helps hold oil leaks...

 

[nj1639]

- before drilling everything out you may like to try using a brake booster check valve in the breather line, creates a negative pressure in the crankcase which has the effect of sucking the seals into the case and helps hold oil leaks...

Thanks, the next project.....

 

[xsjohn]

With or without a breather and using the stock airbox....(and even with the one way breather).....you should drain the lower line to the airbox once a year........oil will collect on the left side while on the side stand and can cause it to smoke from the left for a mile or so when cold......I can loosen mine at the air box while on the side stand and let it drain to clear it............

xsjohn

 

[nj1639]

Duly noted, thanks John.

 

[Wally]

Picked up a brake booster check valve.
Which way is it meant to go inline with arrow points to atmosphere
or arrow pointing to engine head

Thanks

 

[xsjohn]

Don't want to add to the polution on the cooler left......maybe check every oil change till you figure how long it takes to start to fill........bet I poured maybe 1/3 a shot glass out of mine yesterday when I changed oil....hadn't done it in a while........plug cleaned more closely to the right after that too I believe........

looks good wally.............from the engine side you want to be a able to blow and when you suck it should close off........(don't let anyone see you do this though) and I would try it before you open the breather hole......because once the initial air push out the breather and the valve closes you begin the negative pressure and not much air goes in and out after that...........

Wally I bet you never tried the heavier spring on the cam seals........mine leaked for 5 years before I dod than ......never since.............

xsjohn

 

[Wally]

Yes I did John Boy

But only Recently. then went for a 50 K ride with breather disconected from air box & no leaks or oil on side covers.
Put breather hose back on went for ride, when I stopped I put the bike on the side stand & when I came back there was oil around the spark plug & on fins rode home & had oil on side covers.

So thats why Im looking at the breather
I will not dril out the breather yet just ad the valve for now

Thanks All

 

[xsjohn]

Go for it.........that's how we learn things.....(but did you try it with the one way breather).....the original hole is (.220 thousands on the single spogot).........

let me know how it pans..........with the breather hole opened and one way breather (and how much) ....I love people willing to experiment......I learned everything I know that way...................

tomorrow I am going to look at the tower in the stock airbox that stands in front of the intake bell.........to see if there is anything there I should know about it far as a restriction...considering the one way valve is involved.............

xsjohn

 

[Wally]

Thanks John
Im of to the racers soon, Mick Muldoon racing his XS this week end.
www.barrysheene.com.au/

 

[xsjohn]

It is amazing how good we can make these run.........I love mine now at 8-1.....but I am no racer anymore........lucky to have survived all that in my past and now just want it to purr on.........tell them I wish them good luck from up yonder........

xsjohn

 

[xsjohn]

Wally.........I checked my airbox...the newer plastic one....the hole in the tower that sucks the emissions is about .240 thousands........and having one on each carb I can't see an restriction there.............xsjohn

 

[Wally]

Dont know how you Measure it but the puffing in & out with open end hose from the head breather is only very slight
Should it be a lot or little puffing
Could this (Ref No 15) if fitted incorrectly course a pressure problem but Im shore it in right.
Getting close to pulling this one down again over winter

 

[xsjohn]

Do you mean when the engine is running with the one way valve........I notice very little activity when mine is running...........my valve is different than yours though...it's a ball that moves back and forth just a bit.........testing by mouth from the engine side it should blow through (opening the valve) and when sucking from the engine side it should close off and not allow suction...

xsjohn

xsjohn

 

[Wally]

With bike running & no valve in place there is only a small amount puff in & out

 

[xsjohn]

Wally.........its been a few years since I have run it without the air box hooked in........I do remember being able to hear it quite easily...and smell it too.....especially at idol........at higher rpms I think the rapidity of the positive and negative pulse kind of neutralizes the air going in and out..........xsjohn

 

[inxs]

Could this (Ref No 15) if fitted incorrectly course a pressure problem but Im shore it in right.

- difficult to install incorrectly...the tab is up and points forward...its a baffle for the oil return