Forum

[Midge]

But the piston also rises, so its pulsing not pumping. Pressurisation can only come from the combustion chamber leaking from rings, head gasket or exhaust valve stem. If the problem started happening suddenly without anything being changed I would vote rings. First step is to degrease everything so you can see exactly where the oil is coming from. At that mileage I would be tempted to change the piston and rings anyway as it could be a warning of more serious imminent failure.

[simon]

My mate with the collection of Phelan and Moore Panthers has manufactured a flutter valve of such efficiency that the crankcase maintains a reasonably strong engine vacuum throughout the rev range as measured with a manometer. As a consequence the bike, barring a tiny drip from the chain case and a slight smear from the exposed tappets, runs completely dry. I can't see why a proper non return valve would work perfectly so I'm with the chaps who think there is either excessive blow by or a blown head gasket.

[PeteF]

Ogri, I'm afraid your supposition about multi cylinders is incorrect. A lot of twins (the majority?) have both pistons rising and falling together. They just fire on alternate revolutions. Midge also points out that a single does not pump but rather pulse from the breather. The pressure in the crankcase should alternate between pressure and vacuum. A NRV is fitted to preserve the vacuum phase as much as possible. Duckbills are used because they are simple and cheap but also because very little can go wrong with them.

[Skip]

Gentlemen, Thank you all for your comments and ideas. Just clear up any confusion here, the bike is an 08 model pre unit construction lean burn 500 bullet. It has three vent pipes leading from the top of the engine/primary drive casing (there is no vent pipe on the gearbox or none that was fed into the collector pot!) There is a very small pipe leading from the primary drive casing with an inside bore of no more than 3 or 4mm, which I presume is a breather and nothing more. There are two more outlets for pipes on the top of the casings behind the cylinder head, one exits from the side of the timing case the other from the actual engine block. Forward of the previously mentioned pipe fitting is what appears to a hole, it looks like its been there from when the engine was manufactured (having nothing to compare it with I can't say whether it should be like it is or not). I am going to try and attach a photo, it is in this area that the oil leak seems to manifest its self, with that 'hole' filling with oil.



I'm beginning to seriously wonder if I have blown the head or base gasket (or both) when I took the bike for a serious test ride after modifying the gear box, BUT, and its a serious but! Two things; A. a small amount oil goes a long way when hot, the gearbox hasn't lost any to speak of, the primary casing is 'oosing' as normal and the dip stick shows a level about 10m below the top mark.............b. is this just complete paranoia and I should take the bike for a good long ride - taking my AA card just in case and really find out what the heck is going on??? The worst that can happen is I end up rebuilding the engine cos its gone bang..............I'll put the kettle on and buy some Bacon shall I??????

[Skip]

[Skip]

Ha, managed it!! as you can see The black item running across the picture from bottom left to middle right is actually an electrical cable etc. The 'hole' with what looks like a bolt or stud is clearly visible between the above cable and the timing case breather pipe. Both pipes are over a meter long and very secure in place, fitted with clips and not likely to be leaking................As I said in my last post, I'm starting to think that I've blown a head gasket, which is in turn pressurizing the push rod tube(s) and so forth into the main casing and its that hole that is allowing the oil to be forced out as a path of least resistance??????? BTW is it better to source a Gasket Set from H's or from EBay? Apart from the price does anybody know what the quality is like in comparison???

[Mark M]

Skip, just do the simple thing first, that is, take off all those pipes (they are far too long and narrow, there's no way the gases can exit before the next pulse) and fit the duckbill. It's cheap and you'll be setting the system back to it's original design. If that doesn't work then by all means tear it to bits. Seriously, do you want to spend more time in the garage!!!? And buy your gaskets where you like but personally, I'd say it's bad manners to post on here and then spend your money in India!
REgards, Mark

[PeteF]

The black pipe in your photo SHOULD be the DRAIN from the catch can back to the timing chest. There SHOULD be a NRV in this to stop oil blowing out of the timing chest when the engine is running. The original pipe had a wider bit in it which housed the NRV. Some people think this is a breather pipe but not so. If you no longer have a catch tank this should be sealed off. If you do have a catch tank then it must have an NRV placed "backwards" to stop pressure venting from the timing chest. It looks like that black pipe is not the original one. The clear pipe coming out of the top is the engine breather. The engine vents from the crank case, into the oil tank, then via this pipe. This is the one that should have a duck bill on the end (or into the catch tank if still in place. The small pipe from the chaincase is just a breather.

[Skip]

Problem solved (sort of) - it takes the eagle of a wife to sometimes spot the obvious or rather ask it! This is meant as no slur on my missus or anybody elses for that matter. I just made the fatal assumption that everything was as it should be on the bike i.e. everything was as tight as it could be and that just because it had a clip on it, doesn't naturally mean that the clip is also tight enough. You can see where this is going can't you!! Whilst staring at the bike over a brew, which Sally had just delivered, she simply asked if the spigot over which the breather pipe for the casing was tight and not allowing oil to leak?? Was I 100% sure the pipe was on tight as well??? Instead of making an ass of myself and declaring everything tight I picked up a spanner and gave the spigot a tweak or rather half a turn............... Cue knowing look one from Sal, hmm not good I thought....... I then picked up the pipe I'd taken off when I removed the 'pot', the spring clip seemed overly large for the job and again it set off a chain of thought not particularly wanted. The long and the short of it was the pipe I used was over size, softening when warmed up and allowing oil to seap out, combine that with the loose sigot and I had myself an infuriating oil leak........... Having sussed the pipe problem, I decided to do a static test and fired up the engine. Now even I know that an exhaust should not glow orange after the bike has been running for approx 30 seconds, so something not right there either!!!! Glowing exhausts come from an overly lean mixture in my book, and this bike has an Amal Mk1 fitted, one hopes that who ever fitted it sorted the jetting OR I have a partially blocked jet. Further to this train of thought, if the bike is running hot (and it really is) then the oil is being heated massively, leading it to become thin as tea, and able to be blow out of the breather easy as pie. Me thinks I need to check this carb issue out asap. Since I've had this bike all I seem to be doing is sorting out issues instead of riding it!

[Dennis C]

That's one of the problems with these bikes. --------- They attract a lot of owners who really should not fiddle with them to do just that I'm afraid.