Author Topic: LM2 and the dreaded mayo.  (Read 2958 times)

Offline Stevex

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LM2 and the dreaded mayo.
« on: June 08, 2015, 04:10:18 PM »
LM2 with a standard engine and breather setup, except that I've routed the pipe that normally goes to atmosphere at the bracket under the right hand side of the gearbox, all the way back to exit at the rear frame where the seat hinges.
My main reason for routing the breather pipe this way was to prevent the right side exhaust getting covered in crud, as at the time I had no idea just how much, if at all, the engine would breathe.
After a 60-70 mile run at the weekend, I got home to find mayo plastered all over the back of the bike. This is the first time I've had anything come out of this breather.
What springs to mind is that my routing has created a U bend reservoir that has collected this crud and a good run has finally blown it all out.
I thought that a decently long run getting the engine up to temp would prevent mayo forming, and all my runs are long enough and the engine always getting to normal running temp, so why would it produce the mayo?
So, a few questions for those in the know please...
Does the engine need the rocker cover breathers, or could these be removed?
Would it be better to re route the breather to atmosphere to it's original position under the gearbox? I ask this because I'm contemplating routing it to a catchment bottle behind the battery, but this would necessitate a rise in the breather pipe and create another U bend reservoir.
Steve
1980 Le Mans II
2009 Honda CB1300S
2005 Aprilia Tuono
Chief mechanic to wife's 696 Monster

A 'gnat's cock' is an accurate unit of measurement.

Vasco DG

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Re: LM2 and the dreaded mayo.
« Reply #1 on: June 08, 2015, 04:26:28 PM »
Are you running a sump extension? If not that, along with running less oil, will help.

The rocker cover breathers have come and gone over the years, they are far from vital but will assist with preventing Mayo build up in the rocker covers.

Catch bottle is what I've always done.

Pete

Offline lucian

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Re: LM2 and the dreaded mayo.
« Reply #2 on: June 08, 2015, 04:49:53 PM »
Moisture is an inevitable by product of combustion. Ethanol  added to fuel seems to make it worse. I don't know about the lemans but most breather setups route the rocker vents to a condenser box which in turn is routed to the air intake filter box so the crankcase gasses can get recycled through the cylinders. Older motors sometimes vented directly to atmosphere but usually had some sort of oil trap. Shouldn't be to hard to rig one up or perhaps add a condenser box from a later model. Keeping the oil temp above 100 c is paramount to help in vaporizing the water off. I have been using a fuel additive called K 100 from Napa auto and have noticed a great improvement in the amount of mayo on my griso. An oil thermometer is also useful to avoid cold running. Removing the breathers will only make matters worse by not letting the water vapor escape .

Offline earemike

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Re: LM2 and the dreaded mayo.
« Reply #3 on: June 08, 2015, 05:33:01 PM »
Moisture is an inevitable by product of combustion. Ethanol  added to fuel seems to make it worse. I don't know about the lemans but most breather setups route the rocker vents to a condenser box which in turn is routed to the air intake filter box so the crankcase gasses can get recycled through the cylinders. Older motors sometimes vented directly to atmosphere but usually had some sort of oil trap. Shouldn't be to hard to rig one up or perhaps add a condenser box from a later model. Keeping the oil temp above 100 c is paramount to help in vaporizing the water off. I have been using a fuel additive called K 100 from Napa auto and have noticed a great improvement in the amount of mayo on my griso. An oil thermometer is also useful to avoid cold running. Removing the breathers will only make matters worse by not letting the water vapor escape .

I think the hose in question is the vent for the breather box.

My Daytona had a fancy alloy breather bottle, my first V11 a plastic drink bottle. Both did the trick if you're thinking of going the way Pete suggests.
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Re: LM2 and the dreaded mayo.
« Reply #3 on: June 08, 2015, 05:33:01 PM »

Offline Chuck in Indiana

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Re: LM2 and the dreaded mayo.
« Reply #4 on: June 08, 2015, 06:50:59 PM »
I think the hose in question is the vent for the breather box.

My Daytona had a fancy alloy breather bottle, my first V11 a plastic drink bottle. Both did the trick if you're thinking of going the way Pete suggests.

Ya need a Redbull can, man.. something speedy. <insert devil and smile>
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Offline jacksonracingcomau

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Re: LM2 and the dreaded mayo.
« Reply #5 on: June 08, 2015, 07:23:28 PM »

So, a few questions for those in the know please...
Does the engine need the rocker cover breathers, or could these be removed?
Would it be better to re route the breather to atmosphere to it's original position under the gearbox? I ask this because I'm contemplating routing it to a catchment bottle behind the battery, but this would necessitate a rise in the breather pipe and create another U bend reservoir.

1/ No it doesn't need the rocker breathers, in fact in my 38 years with same system the only place I've ever had to clean mayo from is in the breather hoses (u bend) between rockers and breather box. I no longer run them, nowhere now for any to form.
2/ If you rarely do high speed runs, yes

However, IF you do both get it temp EVERY time you ride it AND give it berries, the very best is a catch tank as you describe, mine in front of battery.
Yes, there is a U bend in main hose but a spring in hose to stop it collapsing leaves a clear path for engine to breathe.

But the real answer is
MOVE SOMEWHERE WARMER & DRIER

canuck750

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Re: LM2 and the dreaded mayo.
« Reply #6 on: June 08, 2015, 08:04:16 PM »
I took my V7 Sport out for a good 200 mile run yesterday, highway, city and quiet country roads. When I got home the crud from the breather collected on the centre stand and rear wheel. I have the stock breather hose mounted to the stock lower bracket that connects to the transmission frame bolt. K & N single filter, all stock otherwise. I guess this is what can considered normal?

Jim

Offline jacksonracingcomau

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Re: LM2 and the dreaded mayo.
« Reply #7 on: June 08, 2015, 09:19:06 PM »
I took my V7 Sport out for a good 200 mile run yesterday, highway, city and quiet country roads. When I got home the crud from the breather collected on the centre stand and rear wheel. I have the stock breather hose mounted to the stock lower bracket that connects to the transmission frame bolt. K & N single filter, all stock otherwise. I guess this is what can considered normal?

Jim

Not only normal use but exactly what the machine was intended for
I prescribe this exact treatment every day the engine is started, there will be no mayo after the second day, forever.
If any unsightly drips of oil appear on stand or ground, fit a catch tank

Offline Stevex

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Re: LM2 and the dreaded mayo.
« Reply #8 on: June 09, 2015, 12:39:15 PM »
Interesting and informative replies, thanks.
I did forget to mention I've got a sump extension fitted and thus a lower oil level.
When I removed the rocker covers a while back, to re torque the heads, I noticed mayo running out of the breather pipes.
I think this is where most if not all the mayo is generated.
My way ahead will be to remove these pipes and fit a catchment tank.
Is there any necessity to have the breather box above the engine fitted, or could a pipe go straight from the large diameter breather connection above the engine direct to a catchment tank?
Steve
1980 Le Mans II
2009 Honda CB1300S
2005 Aprilia Tuono
Chief mechanic to wife's 696 Monster

A 'gnat's cock' is an accurate unit of measurement.

Offline jacksonracingcomau

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Re: LM2 and the dreaded mayo.
« Reply #9 on: June 09, 2015, 07:14:17 PM »
Interesting and informative replies, thanks.
I did forget to mention I've got a sump extension fitted and thus a lower oil level.
When I removed the rocker covers a while back, to re torque the heads, I noticed mayo running out of the breather pipes.
I think this is where most if not all the mayo is generated.
My way ahead will be to remove these pipes and fit a catchment tank.
Is there any necessity to have the breather box above the engine fitted, or could a pipe go straight from the large diameter breather connection above the engine direct to a catchment tank?

Yes
The important bit is the oil return that runs behind clutch, the box separates oil from the mist, returns the oil to sump under oil level, lets the pressure out to atmosphere,

Mayo isn't so much formed at rockers but collected there in cold of u bend in pipes, no longer capable of getting boiled out,

If you blank off rocker breathers, also blank off top outlets of box .

While you're in there clean out PCV, if old crimped original, I'd fit later circlip type.

Problem will largely go away in summer anyway, esp if you ride it far,

Offline Stevex

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Re: LM2 and the dreaded mayo.
« Reply #10 on: June 10, 2015, 03:43:52 PM »
Quote
While you're in there clean out PCV, if old crimped original, I'd fit later circlip type.

I thought I knew my bike fairly well, but you've lost me here, could you enlighten me please? 
Steve
1980 Le Mans II
2009 Honda CB1300S
2005 Aprilia Tuono
Chief mechanic to wife's 696 Monster

A 'gnat's cock' is an accurate unit of measurement.

Vasco DG

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Re: LM2 and the dreaded mayo.
« Reply #11 on: June 10, 2015, 05:20:16 PM »
In the pipe that proves outs o he bell housing there may or may not be a ball valve. From memory the Mk II used the small breather box, in fact you mentioned it I believe? If so the PCV valve is a flapper in the box. This is a fairly crappy system that doesn't work very well. I've found that the later ball type PCV valve in the pipe that Martin mentions to be superior. If you are going to use the later valve with the small box though you need to disable the flapper in the box.

The simple way to do this is invert the box and use a punch to biff the pin that the disc of the flapper moves on to snap it off. Then shake the spring out, the disc can stay in the box as its too big to fall out. The box can then be re-installed with a ball valve type PCV valve in the pipe from the crankcase instead.

Pete

 


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