Breather assembly

dave.everitt · Post by **dave.everitt** » Tue May 29, 2012 7:21 pm

I have a problem with the engine "breathing" into the primary chaincase. I assume that the crankcase breather is not working properly. I have the two parts - 000835 and 000836.
Should these be inserted with a washer?
How tight should they be tightened?
Can there be another reason for this primary 'case breathing?

The rings have only just been replaced and I think this is just displacement breathing.

Engineering advice appreciated

iandusud · Post by **iandusud** » Tue May 29, 2012 9:36 pm

If the rings have only just been replaced they may not be sealing well yet. Give it some stick!

Ian

wilko · Post by **wilko** » Wed May 30, 2012 12:56 am

How can you assume it's "breathing" into the crankcase? Are you sure it's not simply being flooded by wetsumping?

1608 · Post by **1608** » Wed May 30, 2012 5:25 pm

If you can feel the draught from the breather then its working well enough. As stated above, you probably haven't given the rings time to bed in.

dave.everitt · Post by **dave.everitt** » Wed May 30, 2012 6:59 pm

The draught I can feel is from the primary chaincase, by my removing the inspection/adhustment access cover in the aluminium case.

My questions are still -

Should the breather assembly be inserted with a washer?
How tight should the breather be tightened?

and a new question:
What size should be used for the crankcase breather pipe?

itma · Post by **itma** » Wed May 30, 2012 8:15 pm

I am puzzled by your puzzlement.

the breather body screws in tight, no washer is needed; the little disc valve should be free to move, do not, for instance, stick it in place with grease or it will defeat the object, a bit of spit is enough.

crankcase breather is same size pipe as rocker feed; point it down not up.

your excess pressure is caused by piston blow by....either the rings have not bedded in, or the bore was not de glazed, or the gaps are far too big; its not out of my experience to find wrong size rings have been fitted.
One assumes also that the bearing spacers are correct and as they should be.

aobp11 · Post by **aobp11** » Wed May 30, 2012 8:23 pm

That vent pipe is 000755, listed at another page in the parts list. You also need union 000513 or similar to attach the pipe.
Albert

dave.everitt · Post by **dave.everitt** » Wed Jun 06, 2012 12:54 pm

OK, Thanks for everyones help. I have now finished this task.
I realised that once the chaincase inspection cap is removed the engine is bound to vent through the primary chaincase. It takes the path of least resistance. I have fitted a new breather pipe of about 1/4 inch diameter and fitted a copper washer under the breather assembly.
Now I am about to replace the two sliding discs on the back of the chaincase that cover the gearbox.
I might end up with an oil tight bike - joke
Thanks for your help

itma · Post by **itma** » Wed Jun 06, 2012 1:48 pm

absolutely no need for a washer under that breather.

quote: I might end up with an oil tight bike

if you don't its your fault.

Marty · Post by **Marty** » Fri Jun 08, 2012 10:52 am

Good try Ken. Makes you wonder why people ask a question originally. You must be mellowing by your response. We want the old ITMA back