fuel tank breather
 

OK I have just removed my tank for the first time ever 2000 SY model.


The tank breather is attached to a tee piece. It is the other pipework to this t-piece I am questioning. One leg disappears down the side of the engine to reappear behind the brake pedal. So question relates to the 3rd piece of pipe.


On mine I have a stub about 3" long that looks as if it has been snapped/torn off somewhere as in the end of this 3" stub is ragged.

I have looked in my Haynes but cannot see anything that indicates where this pipe should be connected. So if anyone can tell me I would be grateful.

OK I think I can answer my own question as I have found a section of breather pipe near the back of the engine that is burnt at the end so assume from back exhaust. This pipe routes round the front of the air box to some kind of trap. Lucky pipe is so long that even cutting off a inch where the pipe has hardend due to burning it will still atttach onto the t piece

If you're referring to the stub at the bottom rear of the tank adjacent to the hinge, then it's not a breather it's the filler cap well drain.

There is no tank breather as such - unless you've got a Californian model, which I doubt - just a hole in the cap to allow air in.

The other leg of the tee piece leads to the coolant header tank, the both drain into the pipe leading down to the clamps at the rear of the clucth case.

Apologise for calling a breather as that is what my Haynes refered to it as. Ok so it is a drain pipe.

I have just checked as I said it was at the side of the air box so assummed it was some sort of breather but as you correctly point out it is the header tank (Never knew there was one) and this is the hose that is burnt through.

So I was correct to reattach it. I doubt it did any damage detached.

All this work for the sake of checking my valve clearance. Even had to buy a set of metric feeler guages as the 3 sets I owned were all imperial. Waste of time the clearences where all inlet 1.1-1.2 mm and exhaust 2.1 - 2.3mm

Now 25 years ago when I was working on engines (R&D engineer on commercial diesels and multifuel tank engines). The school of thought was always to go towards the top end of the specified tolerance if possible. that way you always were sure the valve was fully closing. especially if a bit of crud got into your followers etc. Also when viewed using high speed photography you liked to see the followers rotating. That way it prevented the cam from wearing a groove into the follower. Do these rules still apply today?

Mostly, as the SV is adjusted by shims obviously you can't set the valve clearance to a specific figure - it goes in increments (0.05 mm) according to the shim sizes - but, if there are two shims that would set the clearance inside the allowable tolerance, on the inlets I'd set the clearance at the lower of the two possible clearances, and the exhausts at the upper of the two possibilities. I'd do this as, generally speaking in modern motors, the inlet clearances open up with wear and the exhausts close a bit, setting the clearances as stated simply means the longest period possible before adjustment is again needed. That said SVs seem to go a long time between needing adjustment.

Generally most cam lobes have a slight axial asymmetry over the nose so as to revolve the bucket and even up wear a bit.

PS 0.1 mm ~= 4 thou, good enough for setting SV clearances. :lol: