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[binary]

Hi MartenLarsson, I have had a look at the pictures on your drop box site. The breathing mechanics is totally unfamiliar to me and so I am afraid that I will not have been of much help to you. Some others on this forum that see the pictures may be familiar with this breathing arrangement and may be able to be more helpful.

[simon]

There is no transport and ride position on the oil caps they are just a standard cs type cap and they are supoosed to be tight. The flutter valve in the breather is designed to produce a slight negative pressure in the crankcase. The reciprocating piston is displacing the same amount of air down as up and the valve allows it to act like a vacuum pump by allowing less in than it pumps out. On smaller displacement motors this is less of an issue but a friend with a fleet of 600 Panthers has perfected the art of tuning the escape valve to provide a couple of column inches of vacuum and hence even his exposed tappet motors are dry. If you motor is self saucing it could be that you simply need to put it together with better gaskets but I think it likely that you either has as has been mentioned scavenging issues in which case you would also be likely to be burning quite a lot of oil or you have breather issues. The scavenging can usually be checked by stopping the motor after a run and removing the crankcase plug (not the oil tank one!) If there is a lot of oil in there (more that 100-200mls)then you might need to check your pump and blow out your oil ways. I found all sorts of evil detritus in the oilways of my 51 Bullet some of which could only have got there by extreme stupidity or sabotage. The way to check the engine pressue is to reassemble the breather with its valve and then put a manometer (you can make one out of a length of clear plastic pipe tied onto a lenth of wood in a u bend with water at the bottom) onto the breather and start the motor. If it pushes the water out you have pressure (bad) if it pulls the water inward (good) you have vacuum. If it doesnt go anywhere (ok) you probably have to look at reassembling the engine. With regard to blowby if the breather is under pressure and is producing smoke then its definitely time for new rings. You will also finf that your oil gets black fast and the inside of your engine is black.

[Charlie]

Hi Marten
Just read Simon's post and I completely agree. That last bit about black oil and blow by was very interesting and exactly what happened after my rebuild with new but poor quality rings. Time for a rebore perhaps?
Cheers
Peter