oil in airbox

[tufte81]

I picked up a 82 vision last year replaced the charging system and put on a new starter . now i have a problem with oil in the air box and also fuel petcock doesn't shut off completely
I put a inline shut off valve in and that seem to keep the gas out of the oil . Need some ideas that are not going to cost me
to much cash (wife is ready to kill me already) .

[Walt_M.]

The crankcase vents to the airbox through hoses from the cam covers. There will normally be some oil mist in the airbox but there shouldn't be enough to drip and run. How is your oil level? You said the petcock wasn't fully shutting off and you were getting gas in the crankcase. That problem isn't so much the petcock but the needle valves in the carbs aren't closing to shut off the fuel when the float bowls are full. Have you rebuilt the carbs lately? And, be prepared, these bikes can run into some money.

[Lucky]

Au contrair, I think with the support of this website, the swap shop & Ebay, these bikes are put back into shape for much less than other bikes of the same era, subjected to the same neglect....

[Walt_M.]

A guy I work with says he can do a job 3 ways, cheap, good or fast, pick any two! Same applies here.

[Paul_Jungnitsch]

My Vision has always had a problem with oil in the airbox. Dripping on the engine was just annoying but eventually oil would saturate the filter and cause the engine to run rich, screwing up the throttle response and the mileage. Cleaning the airfilter in solvent works but is a pain.

Now I have both breather tubes vented to atmosphere, the smaller one goes up under the front of the tank through a fuel filter and then down to the ground, the back goes over the engine and down to a nalgene bottle near the right foot peg (I pushed some pcv filter mesh into the line and made the connection to the bottle loose so air would be filtered but still flow easily).

Basically the lines should be filtered somewhat as they occasionally pull air back into the engine, but free flowing so pressure does not build up in the crankcase and wreck your seals. Initially the hose should run uphill as that way the escaping oil has to fight gravity harder. Much more oil escapes out the larger pipe and so the bottle is there to catch it and keep it off my rear tire.

Crankcase breathers in older autos are similarly vented to atmosphere and some hot rod stores sell specially made 'windage' bottles with proper pipe inlets and screened vents.

[Dave T.]

I siliconed the holes shut so it wouldn't drip on the engine. Then I lengthened the rear hose to dump by the front cylinder breather hole. I tried the atmosphere route and it blew oil all over the place. I suppose there is a way to do it like you say Paul_J. I vent my dual sport bike to the atmosphere with a small K&N filter on the end of the hose facing up. Then I siliconed the airbox hole up.

Venting to the atmosphere is like a cold air intake, sort of. Fresh Oxygen instead of re-circulated. I assume it may have more power? I've always wondered how that works... ?:-/

[Lucky]

ok Walt, i'll take cheap & good, lol

The basic problem here you guys are missing is that if you have that much blow-by, your over due for a valve job, rings or both.

[Paul_Jungnitsch]

Not on mine, at least. When I bought it in '87 with 7000 km it had that problem, and as of now it is up to 81,000 km. It has gotten somewhat worse, but not dramatically so. Still lots of power, no blue smoke, hardly uses oil, etc. Doesn't 'puff' breather air at idle, either, never have been sure exactly when the flow occurs. Always meant to set up a long clear hose in range of sight when driving to see at what combination of throttle, speed, rpm, etc the oil made its way out.

I put it down to some problem with oil/vapour separation in the breather assembly, perhaps something assembled differently with mine compared to other Visions.

[Lucky]

could be, usual suspect, in my experience anyway, is that proper break in of a new engine, and proper mainenance has a big effect on problems like these when they get old, but the cause may never be known. a leak down test would confirm things.

[Rick G]

Every Vision I've had the air box open on has this problem , especially if its been run fast (like mine) the solution is simple , use a unifilter and clean it every month or so  and while your in there wipe out the gunk with a solvent soaked rag . Then wash your bike including the engine, (I use simple green ) . Start it as soon as your done and warn it up to dry off and mosture .

[Lucky]

both my 82's and Glens 83 had pretty clean airboxes... all I can tell you is what I observe.  If I ever had enough oil in the airbox to coat the filter, or worse, drip out the weep hole, i'd be very concerned. a properly sealed combustion chamber simply should not blow that much oil!

[Rick G]

Your a lucky fellow LOl  Seriously there 22 years old  and not in there prime , a little blowby dosen;t worry me.

[tufte81]

thanks for all the info . i had the carbs gone through last year along with alot of other repairs . i got this bike real cheap but now i got a quite a bit invested . i guess its an addiction once you get started you can't stop . one thing for sure is this bike is blast to ride !!!

[ofstone]

I found in my airbox, when i opened the box a lot of oil, and also a original yamaha airfilter, but that one was loose in the airbox. At first thought i thought the foam 'seal' on the bottom whas shrinked thru the year. But when i bought the new original one, i was suprised to see that this original one whas about 1 cm higher than the old one exluding the foam! It looks exactely the same and has the same number on it. maybee the old one is a faulty one?

But back to the oil in the box.
I also found the filter was a little bit soaked with oil.
I also found 2 tubes going to a cam-cover of the engine.
One small diameter tube goint to the front cover, posibly to let oil drip back in the engine, and one big diameter tube going to the rear cover. Inside in the box there is some kind of tube with a plastic bend in the hole from the big tube.
I think this tube is to prevent oil vapour and spray from flying directely to the filter element and is directed to the bottom of the airbox.
Maybee this tube in the airbox is missing on your bike?

Maybee the brand and type of oil used is also a factor for causing more oil to 'vaporize'.

[jasonm.]

Ofstone, You described exactly what goes on inside the air box. GOOD MAN. Oil resides to some extent in most cycle air boxes. Nature of the design. Since we don't have auto type PCV valves. Dripping down on the carbs ?outside of the box is a simple job of cleaning completely and sealing with Permatex ultra black.

[Jeff]

I had that problem with mine but about a year ago but read here from the ole wise ones on brand and wieght oil used.  I was using 10W-30 Castrol but switched to 20W-50 Castrol.  Since the switch, no more problem...
jeff

[Lucky]

Who you calling old?  :o
don't forget, I know where you live (sorta)  ;D

[Paul_Jungnitsch]

Brand and weight of oil does make some difference, as does how many miles on the oil (some of that dreaded 'viscosity breakdown' that Castrol goes on about?). I use Castrol motorcycle 20w50 though, which is about as good as one can get without going to synthetic. Do sorta wonder about how Mobil I 20w50 would perform, but not sure on the non-motorcyle part.

Some truck engines have the same problem:

http://www.turbodieselregister.com/forums/showthread.php?s=&threadid=73627

I'd always meant to do the same thing on the rear cylinder (install an automotive add-on oil separator) and actually bought one, but on the Vision there simply isn't room to squeeze one under the fuel tank.

[jrransom]

83 models have baffle in the forward head that prevents most oil from ending in the air box you have to remove head to see the baffle the yamaha web site shows the baffle listed for 83s could use better baffle or try inline pcv to prevent oil in the air box