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My bike does not have the flexible pipes (part 5) or the pipe fittings (part 4). Instead I have a blanking piece (looks like a big plastic screw from above) where the pipe fitting would go in each side of the airfilter. Will this affect the running of the bike, or the effects of the oil recovery system? I have two pipes (parts 12 & 13) running to the oil recovery tank (part 11) from the rocker covers, and a larger dia pipe (part 25) from the bottom of the oil recovery tank to the rear of the crankcase. The remaining two nozzles on the oil recovery tank where the (non existant) pipes would go from the airfilter are just left open, not blanked off.

Oil recovery eh? How commendable. I just have the usual couple of "running sores" on mine,ie breathers terminating to open air. (actually into microscope oil bottles? why not onto the chain or somewhere useful like that)) but on my much older Beemer the oil goes out of the breather and back into the air intake,making the filter dirty, due to a bit of blow by (and why not at 150k miles)
I think let 'em breathe.

My 500-6 does not have the fittings (part 4) into the airbox, there is just a moulded circle where they would attach.
The two tubes (part 5) were fed into the air intake hole at the front of the airbox. It had always been like this.

A while ago I replaced all the tubes on the breathers as the original ones went very hard and brittle. I used thicker walled tubing and afterwards the bike ran really crap and would not take full throttle.

If you check out the area of the airbox intake you will see how small it is. The thicker tubing I used was enough to strangle the intake and make the engine run too rich.

Now I just vent the tubes down behind the engine.

My bike has the same set up as yours, ringer. I took it for a 20 mile test run today (just got it and taxed it) and there was a mess of oil leaking from the crankcase pipe lower joint. The clip was loose and the oil contaminated and thin, so not a surprising result.
Having now tightened the clip and done the oil change, I'd like to know if all you old hand 500 owners have kept the breather system standard or not? It's obviously meant to provide a breather chamber with a slight negative pressure when running, and a catch tank for oil mist that drains back when you stop the engine. No doubt all to do with saving the planet, but is it any good? If you've never needed to look at it, it must work, right? If someone has seen fit to alter it, was it giving trouble? If there is any history, I can't see it, so please put me right or I may have trouble sleeping.

So what was the result when you fitted an old style breather tube with baffle as on the old 350's?

**Hot tip for the day** If you fit longer rear suspension units to raise the ride height, check that the mounting eyes are the right diameter for the bolts. If they are too big you lose the extra height and a bit more besides, so your arse end is droopy. Simples.

Hello! is there anybody there Was it something I said? Oh well, for the benefit of anyone looking in, I think the standard set-up is good. It will draw the crankcase gases (well some-enough to stop there being a positive pressure in the crankcase) As long as it is drawn in through the top as original, it won't make a mess of the filters and you should get less external lubrication of the bike. Or is that what we British bike owners aim for? you know, rust prevention and all that.
I think if you rely on leaving the two top outlets open, because they are only about 5mm each, and vented to the atmosphere,(positive pressure) they will be a little restrictive perhaps? The chambers volume may make up for that restriction, but you still won't get the slight negative pressure that is desirable in the cases. Lots of other engines have one way valves in the breathers to acheive this, and they don't generally leak-as long as they keep working-which is a subject that drives owners of Norton twins round the bend. The baffles in the rocker cover vents and the old style 350 main breather pipe do this job well enough, but obviously don't recirculate the nasty blow-by gases.
So, what does the team think?