Oil mist question ('83 SP1000)

[berniebee]

So I completed my first Guzzi build* this summer and I enjoyed several rides before Ottawa's frost and snow finally forced the SP1000 into storage. (As I type  this, we're expecting a foot of the white stuff today.)  After any spirited riding session, I would see an oil mist coating my right muffler, swing arm and unfortunately some on the rear tire too. Not exactly confidence inspiring.

The mist comes from the output of the breather system. This breather box came with the bike project:



I'm confident I have the hoses routed correctly. (Pair of pipes forked together go to valve cover vents, thick pipe goes to engine vent, thin pipe goes to oil return, angled pipe is vent to atmosphere.) I've installed an outlet hose from the breather box vent pipe which is routed down, then rearwards and ending just under the pivot point of the swing arm, right side. It's obviously emitting the oil mist.

The breather check valve that resides inside the thicker hose going from the crankcase to the breather box was not installed.



 But the spring loaded flap inside the black breather box works and has been left in place.


I just realized that Dave Richardson/Guzziology recommends the reverse:  disabling the breather box flap and installing the breather check valve.  Will doing this completely eliminate the oil mist?  If not, what do you think about connecting the breather box vent to a inexpensive catch can like this one, as a secondary oil recovery system?




Please don't recommend a sump extender ($$$) unless you intend to give me one!

*See "Bernie's Budget Beast" in the Bike Builds section for details.

[acguzzi]

admittedly I race mine but it does breathe oily mist, I have a catch can that I empty periodically, makes sense that a "spirited ride" would do the same, I have a deep sump and a roper plate but it still does it.

[guido guzzi]

Guessing that you already know to keep the oil level about half way between min and max on the dipstick...

[moto-uno]

  That valve that's not installed would be my first move . The 2 working together reduce the mist from the hose
significantly . Try the OEM way before all the work arounds . Even in my custom bike , with home made breather,
basically mimics the original and it generates very little mist . And to add to this , the engine in this custom has
not a single new part in it , assembled from various ebay parts over 5 years ( yeah , I have a Scottish side :) )
Peter

[berniebee]

Guessing that you already know to keep the oil level about half way between min and max on the dipstick...

Actually, I think I read about this elsewhere and forgot. Thanks for the reminder, I will try this.

[berniebee]

  That valve that's not installed would be my first move . The 2 working together reduce the mist from the hose
significantly . Try the OEM way before all the work arounds . Even in my custom bike , with home made breather,
basically mimics the original and it generates very little mist . And to add to this , the engine in this custom has
not a single new part in it , assembled from various ebay parts over 5 years ( yeah , I have a Scottish side :) )
Peter

Hmmm. I reread Guzziology and Dave R. says to disable the breather box flap only because it can become "restricted" (His word.) I'll try your suggestion in the spring. Thanks!

[glenm64]

 The flapper valve in the box doesnt really seal very well (easy to check just by sucking on the tube).
I ground the welded seam off, removed the flapper valve, filled the box with a stainless steel scourer pad and welded the box back up.
 I installed the ball type check valve. Hasnt been an issue since.

[Antietam Classic Cycle]

JMO... You definitely do not want both the ball-type check valve and the one in the box! They can counteract one another and cause pressure build up. Look at the openings in both: the ball type has a 8 mm(?) hole for air to flow through, the box has a 12 mm tube. Which one do you think will flow more air? I use the flapper in the box if it's intact.

I also only run 3 qts. of oil. The only time I had even the slightest bit of oil vapor out of the "atmosphere" hose was when I briefly tried Valvoline VR1 20w50. Never did it before with Rotella T4 15w40 and still doesn't since I switched back. '76 Convert with 48k miles and original iron lined cylinders.

[John A]

If you use a ball check valve, use the type that the ball cannot close off. Easily identified by a square hole versus a round hole. With a round hole the ball can lodge and stick. Then the breather is plugged. At road speed, oil is forced up the oil drain in the crank case until the oil level goes below the end of the drain. It will pump about a quart out the external drain in thirty seconds, if it happens. The oil goes into the air box or out the end of the external drain depending on how you have it plumbed.There was a design change that incorporated a square hole sometime in mid ‘80’s. You can modify a round hole to a square hole with a file.

[Don G]

Maybe perform a leak down test, could be a blowby fault.....   DonG

[chuck peterson]

On the outlet hose, I’ve run mine longer by threading it past the rider’s left side swing-arm pivot and along the swing arm, past the rear brake and below the axle. Tie wrap is your friend. Now you’ve a outlet spot where the mist disappears behind and below a lot of important parts.
I was replacing the outlet hose with an available thicker one and couldn’t squeeze it between the Vert trans and rear axle. I draped the new one and it seemed to flow very nicely along the arm, leaving about a three inch heater hose spigot hanging unseen below axle and rear disc. Worked neat. I was lucky to have found the sump extender too