Mike's breather valve: tips...

TeeCat · Posted: April 28, 2009, 10:32 am Post subject: Mike's breather valve: tips...

Hi, all...

I'm just starting a new thread on this because I wanted to make sure people see it; it may be helpful for those planning on installing the breather valve from Mike's.

The valve is surprisingly large... occupying the better part of your palm. Don't be led into thinking that this is some tiny little gizmo. I really wanted to try it because it's reported to work, so I fussed with it a lot, and thought maybe I could save some others the trouble I had. No need to cry and skin those knuckles now! Razz

This applies to bikes with stock battery boxes and pods, primarily. The best place to mount the valve is on the front center vertical battery box support. Place the valve with the inside surface of its top mounting tab against the left outside surface of the battery box support, inlet facing forward, as high as you can get it. Mark the position of the hole in the mounting tab and tap a hole in the support that's just large enough to a accommodate a self-starting hex head sheet metal screw. Affix the valve.

This will allow you to run your lead hose relatively unobstructed from the right spigot of the breather (plug the left) to the valve's intake barb. Use a spring to keep the hose from crimping too much as it comes off the spigot and contacts the right carb top. Then run another length of hose from the valve's exit barb down behind the crankcase to a small breather filter to catch any mist. This setup is neat and clean.

ine's exhaling - I hear the telltale wheeze - but we shall see whether it mitigates or cures my one remaining oil dribble.

Hope this helps others. Maybe this will be "vault worthy", Y-man? Smile

TC

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

I'm not convinced on how worthy these things are yet...........Good luck TeeCat

TeeCat · Posted: April 29, 2009, 9:07 am Post subject: Re: Mike's breather valve: tips...

skull... I don't have much doubt that it works as intended. The question, in my case, will be whether it actually addresses my issue successfully.

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

TeeCat, my question is, if Yamaha made these bikes for 14 years then why didn't they put a one way valve on them..............

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

TeeCat.....off subject for a mo...............have you ever checked to see if you bottom and top case have matching no's?...........thinking about your weeping main seal

penn71911 · Posted: April 29, 2009, 6:08 pm Post subject: Re: Mike's breather valve: tips...

" if Yamaha made these bikes for 14 years then why didn't they put a one way valve on them.............."

Same reason they didn't change to a permanent magnet alternator... or fix the crappy fuse block... or upgrade the crappy sump filter... or do we even want to talk about the clutch?!?!?

Sorry bro, don't mean to sound harsh that's not my intent, but sometimes the solutions (and problems for that matter) don't show up till way down the road...

I personally run a power brake check valve on my '82... just because I believe the theory is sound. I can neither confirm nor deny the claims... I didn't leak before and I don't leak now so who knows?

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

doubled up Rolling Eyes

so edited out

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

I go back to the idea, that a lot of misconceptions have happened with this bike............one is the clutch, it is not the smoothest and is heavy.........most of the problems have been the build up of dirt on the plates.........solution.........a light bead blast to roughen them up and they are perfectly good (if within tolerances), and using the wrong oil contributing to the slippage.....solution.........a light bead blast, etc.....The engine is a different matter to the electrics, the main problem with the Stator/rotor was the protective coating used on them broke down. Maybe after 20 years the new ones sold will have the same problem...........the fuse box was probably not on the bike long enough before the faults started to show up, by then the bike was discontinued...............would be interesting to know how many bikes blew up because the bottom sump filers were crap, more to the point how many and how long did these bikes ran around with the bottom filter broken with no mechanical problems at all ...............Just my opinion.........

penn71911 · Posted: April 29, 2009, 6:59 pm Post subject: Re: Mike's breather valve: tips...

Very true, in my opinion, I think the reason they didn't do it was as simple as 'why bother?'...

I mean, cars have PCV valves... essentially the same thing... the XS turns more RPM's and probably 'puffs' more with both it's pistons moving up and down at the same time, creating a lot more havoc in the crankcase than...say... even a v-twin where you've got one piston coming down, while the other is going up, 'sort of' canceling the pumping action out... or doing a better job anyways...

If they had to build the same motor today, I believe they would have a similar valve, for emmisions sake if for no other reason... just my opinion!

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

Guys..

The reason you need one of these valves is simple. Its called "pod filter".or generic K&N's in my country.

As soon as you remove the standard air box you remove the intake derived vacuum that is designed to keep a constant negative pressure in the the cases. With both pistons moving up and down at the same time, gives good potential for forcing old seals and causing leaks. Not on everyones machines, but on mine it did...

It still does, because I didn't quite get round to putting my breather in yet! LOL..

The valve lets the gases out on a downward stroke and closes fast enough on the upward stroke to maintain a slight negative pressure to replace the lost of the airbox.

There are emissions issues, but these dont concern me as a motorcyclist in the UK.

Airbox is best for cases and seals but not quite so good for flow.

THe best solution in a road bike, is to use the standard airbox and well maintained standard carbs with good fuel filters (as recommended by RG something I learnt the hard way).

Various states of tune vary the need for the airbox, but if you do without it, a valve is a must imho.

penn71911 · Posted: April 29, 2009, 7:25 pm Post subject: Re: Mike's breather valve: tips...

Jake68.... Where you get off tryin' to make sense?!?

JUST KIDDING!!! Laughing

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

the earlier bikes had the hose venting to the air, later bikes back through the carbs. Maybe for emission reasons, ( the problem is we don't realy know why the engineer done this). But we do know that it is important not to enlarge the breather hole.......As the rings get worn, the pressure in the crank will build up with a one way valve. Where is that pressure going to go?........As i see it that is why the size hole in the breather is so important, to big no pressure at all, to small or blocked off/one way valve will let it build up and force the pressure back out the rings/seals...........

dps-rider · Full Member Joined: Aug 25, 2007 Posts: 100

I mounted Mike's breather directly in the hole where the double nipple adapter was pressed in and it can be installed or removed easily.

First, I modified the breather as in the picture below. Not noted on it is that I had to grind the housing of it a bit so it would clear the frame when installing it.

The breather fits into the hole where the nipples were originally pressed in using a bushing to adapt the size and an O ring to seal it. A bracket holds it in place with 2 screws threaded into the labyrinth filter housing.

I unbolted the original outlet adapter and capped off the hole with a plate and a gasket. Then a new hole was drilled and tapped into the housing where I mounted a homemade T adapter.

I started out with the hole in the T relatively small (1/8"?) and the thing wheezed for a couple of seconds when I shut off the engine. Took it apart and drilled the holes quite a bit bigger and the wheeze is very short in duration now with no detrimental effects.

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

Jake68 why did the earlier engines not have the breather hose going to the air box's/

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

[quote="Jake68"
As soon as you remove the standard air box you remove the intake derived vacuum that is designed to keep a constant negative pressure in the the cases.= quote]
It is not the air box's that keep a constant negative pressure in the cases but the size of the hole in the breather............I think with the hose from the breather going into the air boxes does 2 things. ......... recycles the fumes from the crank case, EPA purposes, and no oil dripping on the ground........

penn71911 · Posted: April 29, 2009, 8:02 pm Post subject: Re: Mike's breather valve: tips...

"It is not the air box's that keep a constant negative pressure in the cases but the size of the hole in the breather"

Well... the carbs suck air through the airbox which creates the negative pressure to pull the fumes from the crankcase... I guess 'technically' it's the filters that cause the flow restriction that causes the negative pressure between them and the inlet to the carbs which in turn pulls the vapors from the crankcase... while the hole in the breather may affect the flow, the overall vacuum is created by the suction from the carbs in the 'enclosed' airbox.

If you were to say... plug the inlet holes in the airbox, the vac level would increase because the only place to pull air from at that point would be the crankcase.

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

All I know, is I had a chat with an "expert" in crankcase breathing, from a website I found online.

It was him that informed me that that open breathing is never really enough.

There are many older bike owners, brit bikes, and classic japs that have the same problems. Crankcase pressure from an otherwise heathly engine causing leaks and oil loss. All the british bike guys are using valves...

I would suspect that the once the breather setup has changed by means of improving crankcase breathing as well as emissions.

After all, if you could KNOW that you had a vacuum by fitting an inexpensive valve, then do it?

xsjohn

dps..........thought that was the best way....up close to the engine.........made mine in the tube close to the engine......

A pump I suppose it the most modern way..........

xsjohn

Retiredgentleman

I agree with what Jake68 is saying. If you have no airbox, then using a brake check valve is the way to go.

The last couple of years I had the crankcase vent going to atmosphere with foam filters. I did that mainly because I knew I had top end problems, such as high oil consumption. Engine would drip a littlle oil, due to leaky gaskets.

Now that I have re-built the top end, I decided to go back to the stock set-up, with 2 vent hoses going to the air boxes. The partial vacuum from the air boxes will keep the crankcase slightly negative. The Yamaha engineers knew what they were doing. Not many kms yet but so far engine is running great, with no oil leaks.

xsjohn

Well I have an airbox and a valve.......best of both worlds...

xsjohn

tito650

the best way to keep a negative crank case pressure is either a pump ...fat chance of that....or like was said let the engine vacume do it no reason not to. even though i'm running pods i plan on puting in short tubes between the pods and the carbs ...... then connect the tubes and tee in the breather... with less crank case pressure it should keep the oil where it needs to be Smile

TeeCat · Last edited by TeeCat on April 30, 2009, 8:41 am; edited 1 time in total

Chris, John, tito, RG...

You know... I still have the stock air boxes for my '73 sitting on the bench. When I first got her, I pulled the boxes off - they had no filters inside - and after I got her running I went to K&N oilcan pods. They're pretty big and I was thinking of going to smaller K&Ns, but since everything is behind my fairly pristine sidecovers anyway, I have begun to consider getting a pair of stock filters and seeing if the stock boxes will fit with the Mike's valve between them where it's installed. That way, I'd have the stock intake config, and a Mike's valve that exhales to atmosphere, but with one side plugged. I'd be curious to see how that would work for controlling my last - and most persistent - oil dribble.

Temped to pull the side covers and see if the original filter boxes will fit. Sure can't hurt anything...

TC

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

Pen79111 wrote.......... "I personally run a power brake check valve on my '82... just because I believe the theory is sound" .............I am asking questions and trying to get my head around this and looking for some facts, no one has given any facts just statements like............... "I believe"... .......No basis for fact in i believe

TeeCat · Posted: April 30, 2009, 8:58 am Post subject: Re: Mike's breather valve: tips...

skull, I think the closest we've come to "fact" is what Jake has learned from his evidently knowledegable compatriot, and that these bikes seem to be prone to oil leaks in the presence of excessive crankcase pressure. Everything else is educated experimentation in the pursuit of facts. Once one or more of us licks this issue reliably... then we'll have more facts, which will then be universally applicable when this problem arises for others in the future. Meanwhile, all we have is theory, based on physics.

Remember, too, that those of us with at least one persistent leak have a vested interest in turning contemplation into action... hence our willingness to diddle with anything that looks like a viable fix. Even if I were armed with a rucksack full of facts, it wouldn't matter until I got my hands dirty with what makes sense to me, though it might not be empirically demostrable at the moment. What we are doing now, though, is based on reasonable science, and for the moment it's all we have.

TC

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