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By Kally
#95887
Hello, I have A 2003 very low mileage (good compression) 500 Bullet ES and am getting a little oil blow-back into the air cleaner box. This model appears to have the anti pollution stuff fitted (braided pipes from the exhaust and engine breather to a little canister) and clear pipe into back of airbox, any one had similar and know a easy fix ?? regards kally
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By stinkwheel
#95889
It's comparatively easy to remove the emissions stuff altogether and fit a simple duckbill breather hose. You need to blank off the exhaust stub (our hosts sell a cap for this), blank off the hole in the inlet manifold (many people use a self tapping screw with RTV on), blank off the stub in the timing chest and fit a simple duckbill breather hose to the oil tank breather. Point it at the chain.

That said, the exhaust air valve (exhaust and carb) isn't part of the breather system, it won't be making oil appear in the airbox, it just bleeds air into the exhaust to reduce unburned hydrocarbon emissions. The breather system is probably where the problem lies

If you don't want to remove it, I'd check that the catch can isn't all full of mayonaise/oil/elephant snot and that the hoses leading to and from it are clean and clear. There should be a duckbill type one way valve in the cannister itself on the end of the hose leading from the oil tank and there is a one-way valve in the hose leading down to the timing chest stub. It is not unusual for the whole setup to become completely full and blocked with emulsified oil (mayonaise).
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By Kally
#95893
Thanks for that, I will go for the breather pipes and canister and strip and clean (elephant snot) I like it lol :lol:
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By Adrian
#95895
On late pre-EFI breather systems a clogged breather can have the crankcase gases forcing their way out of the pipe at the timing chest and, unfortunately, loads of oil with it. There's a short duck bill under the timing cover which is supposed to be a one-way valve but it's pretty useless. This oil then pours into and overflows from the air cleaner box. My old Electra-X did this.

A.
User avatar
By Allanfox
#96163
My 2008 350 has just done this and the 'snot' was suddenly everywhere! Also just after a good clean and polish :-(

Exactly as other have said and the whole system was just full of it, stripped and a good wash out with paraffin and fine, I think we need to check the catch can regularly, first time mine has done it in a year so a bit random but maybe it takes that long to fill up? My oil looks fine so guess the emulsification is like foam that builds up.

You do get a bit of oil in the air box as the 'air' has oil vapour in it so will build up a bit and needs the odd wipe out but a sudden increase seems to mean system needs a clean out, look at the photo of the inside of my air filter box!
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User avatar
By Adrian
#96164
Bad pipe runs don't help, unless there's an uninterrupted vertical rise to the breather from the breather port on the engine (the hose tail on top of the oil tank in your bike's case) the grey gloop will form a blockage.

Best things for your breather:

1. A short length of hose with a 90° bend in it to fit on top of the breather port, you can re-use some of the original tubing;
2. A proper non return valve to fit the bend above, forget the duck bill;
3. A longer section of hose running to the back of the bike along the rear chain guard, make sure it has no upward bends in it.

Then you can remove the catch can altogether as well as the pipework to the back of the timing chest and the air filter box, plug the relevant holes,some pipe/jubilee clips for the remaining hoses, job done.

A.
User avatar
By windmill john
#96165
I find this mayonnaise confusing! My 2002/2006 350 Bullet has it in the oil.
Now, the PO did the correct mods, Adrian pointed these out to me a year back:
Stubby pipe from valve of timing chest correctly blocked.
Large bore pipe from top of ‘oil tank’ towards back wheel, with a one way valve fitted.
And just had new piston and rings and a honed bore.
A decent ride of a few miles, so engine suitably warm, I shouldn’t have Mayo!
User avatar
By Allanfox
#96166
Hi Adrian, yes done this on my 500 AVL as part of the rebuild (and advised by you), crankcase port opened up and off to back of bike (not finished in photo) and oil tank staying at air filter for now as interested to see what difference in venting pressure with crankcase port opened up, if oil does go into air filler I will have to run alongside the other one . Not running yet but soon.

If you vent at chainguard dos it not risk an oily rear tyre, or am I overthinking it?
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By stinkwheel
#96168
My 350 produced huge amounts of mayo despite having a straight duckbill breather on the oil tank and doing an average of 150 miles a day for 2 months. To the extent I got into the habit of detaching the breather hose and blowing it out into a paper towel at every fuel stop.

It stopped doing it the day I fitted a scavenge side pressure relief valve from our hosts and has never done it again (in 10 years)

Don't ask me why...

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