I have the vent tube on the breather routed down between the starter and gearbox casing, but already there is a tremendous amount of oil on the underside of the gearbox casing, and quite fresh following the recent change.
Is this the correct routing - out of the larger left side port with a slight turn towards the rear of the bike ? Not as lot of space for the 13mm iD hose required.
Should the hose rise first ?
is this meant to affix to a fitting I can’t see ? The manual is very vague. there was nothing at all on the spigot when I bought the bike.
You should have various pipes plumbd into the box.
The large pipe connected to the crank case vent. This sometimes has a flapper valve inside, but is often disabled and crank pressure is controlled purely by the ball valve in the crank vent.
A smaller return pipe that drains any oil back to the crank cases. Visible in the photo.
2 x breathers from the rocker boxes. For some reason I was told to reverse the rocker boxes when I fitted mine long long ago, but I can’t remember the logic in this.
A drain pipe that drops down between the gearbox and the starter and vents to the ground. The pipe is yet to be fitted in this photo, it’s lying across the topo of the gearbox. You can see the stub that it fits onto on the bottom left of the box
I hope this helps.
It could be that the oil return from the breather box to the crank case is blocked, allowing the box to fill up then pour out of the hose to atmosphere.
If the main large crank vent gets blocked, or the flapper valve inside the box gets stuck, the crank cases will pressurise and force oil back up the return pipe until it overflows out the larger vent pipe.
My understanding is that the smaller crank return pipe is flush with the bottom of the box and that the larger overflow has an upstand so oil should drain down the return pipe rather than out of the larger pipe.
1 Not seen the top hat device shown. looks simple enough
Is the OD the same as the spigot hose ID i.e. 13mm. I could make this on my lathe in about an hour or so from some stainless bar, plus easy to find a suitable ball bearing.
But where to I plumb this to ?
2 As per Don’s reply - exactly as per your photo except mine is turned so the large bent spigot faces towards the back of the bike. The hose I have fitted to this is where the oil is gathering and after just a 2 mile trip.
The breather valve top hat ball valve device drops into the larger stub pipe that comes up from the crank cases. The -ve pressure caused by the pistons rising pulls it down & the +ve pressure caused by the pistons descending lifts the ball. It is designed to create a lower pressure inside the crank cases, ie air can escape when the pistons descend, but cannot be drawn back in when the pistons rise as the ball falls to the bottom and seals the pipe.
Mine just has 2 pieces of pipe approx 2 inch long between the crank cases and the breather box on the crank vent and return pipe. The bent pipe faces left to drop in the narrow gap between the gearbox and the starter motor.
Does your breather box have the flap valve inside, this sort of replicates the ball valve, ie it lifts up when the pistons descend and is pulled shut when they rise. The general view is that the ball valve is better and you should knock out the flap valve.
I used to plumb mine into the frame, there was an inlet near the front of the petrol tank, and two outlets down near the seat, one I used as a return to the valve and the other I Routed out over the rear mudguard like my old Triumph. I had the collector box but could not work out how this operated. Dave R
