Crankcase release valve

[Ozmadman]

Hi
Further to my issues with the knocking sound on my model 8... cannot find anything significant on the timing side so will now check the primary side. If nothing is there then all I can presume is that the crankcase release valve stator is the cause. Below is an extract from the workshop manual that seems to indicate that a fix is possible for the old engine numbers, which mine is, with the engine in situ as it mentions lining up the hole in the stator with a spoke to re-fit the tube?? dismantling being necessary only if you want to do the modification. Has anyone done this and is this how you would read it??

" On engines with a number before
6850 a rattle can develop which can be mistaken for movement
in the big end assembly. This rattle is due to movement of the
crankcase release valve stator 042220. The noise can be overcome
by removing the release valve tube 042221 (which locates
the stator) and increasing the effective diameter on the end of
the tube by an electrical deposit of either chrome or copper.
The tube should be thus treated over a length of 3/8" from the
tube end. Alternatively the engine can be dismantled to use
a modified tube 044083 and stator 044084. The new stator is
threaded internally with a threaded tube. If difficulty occurs
in inserting the release valve tube, pass a spoke or similar
object through the aperture in the crankcase, rotate the
engine slowly until the hole in the stator is in register."

Thanks Paul

[clive]

Never done it Paul as I do not have a lightweight but the way I read it is that if not fitting the moded threaded tube (and hence disassembling), you will need to remove your tube and electroplate the end with copper. (I have a vague recollection from many years ago that this involves copper sulphate a sacrificial anode and an electric current but I am sure that google will clarify). The spoke comes into play to make sure your have the stator lined up before you bash the modified tube back into it. Certainly worth a try. Liked you video by the way but not the sound!

PS I am known as a bodger in my local section so this sort of repair really appeals to me!

[JohnHewes]

Loctite?

[Ozmadman]

Never done it Paul as I do not have a lightweight but the way I read it is that if not fitting the moded threaded tube (and hence disassembling), you will need to remove your tube and electroplate the end with copper. (I have a vague recollection from many years ago that this involves copper sulphate a sacrificial anode and an electric current but I am sure that google will clarify). The spoke comes into play to make sure your have the stator lined up before you bash the modified tube back into it. Certainly worth a try. Liked you video by the way but not the sound!

PS I am known as a bodger in my local section so this sort of repair really appeals to me!

thanks, that's the way I read it too..as for the video, the whole purpose really was a to record the sound so I mounted the camera of the down tube right in front of the engine, the picture was just how it came out. When I get it sorted I will do a proper video of the ride.. thanks Paul

[Ozmadman]

Loctite?

possibly but the bit the tube goes into will be covered in oil so probably a no go..

thanks Paul

[cbranni]

Paul, you gone this far why not pull the engine out, split the cases and check it all out, when you split the cases you will be able to check the breather tube fit in the stator, I don't quite understand how it makes a knocking sound but I suppose if it is loose it would rattle around and it would get worse as it wears down, it must have been an issue otherwise they would not have done the mod.
The bolt is steel and the stator is aluminium so its the thread in the stator that wears, I don't think the plating cure is very good, it would be better to plug and re-tap the stator but I may have a spare somewhere so it may not come to that.
I am more concerned about your lack of endfloat if I read your post correctly, with the timing gear nut up tight there has to be minimum of .020" movement, if there isn't something isnt right.
Also have you checked the timing side bush, place a lever under the timing gear and press down there should not be any movement up and down cept for few thou.
I know your bikes are outside but it won't take long to pull the engine out, if you do split the cases don't forget to pull the oil pump out first.

Colin

[Ozmadman]

Thanks Colin may just do that actually then at least I will know for sure whats what!! A couple of things that have confused me though. Firstly this breather stator thing.. What I copied above from page 25 of the manual about the rotor/stator thing indicates that the original stator (before eng number 6850, which mine is) had a plain hole in the stator and end of tube so an interference fit hence getting it plated to take up the wear, then there is a mod ( a threaded stator and threaded tube) simple!! until I read on page 43

" Note: On engines after 8979 an improved type of release
valve is used. The stator is retained by a short bolt below the
bearing housing. When refitting this stator the recess should
face the engine sprocket side of the housing. The new valve
cannot be adapted to earlier type crankcases."

So, was there a further mod after eng no:8979 where the crankcases were different altogether?? confused now!!

Also you mentioned that "The crankshaft end float, without the alternator rotor fitted must be greater then .020". If it is not the inside face of the timing side bush must be machined" A bit unclear? as the rotor does nothing to change the end float as it is just goes up against the drive side crankshaft gear. So do they mean that "The crankshaft end float, without the alternator rotor AND GEAR fitted must be greater then .020"?? if it does then yes I have at least that amount of float but with the gear fitted there is a minimal amount oh, and those shims behind the gear are they to adjust end float or just to line up the drive and clutch chain line??

Finally, I have levered under the timing pinion and can't detect any movement at all and can I get the engine out without disturbing the gearbox

many thanks

Paul

[John Jarrett]

Paul,
On the stator retention... Early engines have a threaded hollow tube/bolt. It is hollow over its entire length and circa 3/4" of the bolt where it fits into the hole in the stator in a plain tube. The threaded portion nearer the bolt head threads into the crankcase to locate. The breathing then goes through the hole in the tube. In the stator there is only one hole to register with the tube of the hollow bolt.

On the later engines, there is a drilling in the crankcase which acts as the breather and lines up with a hole in the stator. There is a separate threaded bolt that locates the stator though the crankcase. This is a normal bolt and much shorter than the earlier hollow bolt as it goes into the stator from below and not the rear of the crankcase. In the later engine stator there are two holes, one threaded to take the bolt and the other is just s hole for the breather.

I hope that helps and if you need any pictures, please let me know.
John

[Ozmadman]

Thanks John for the reply those descriptions have helped and I will find out when I take it apart but the manual does mention an intermediate one it seems with a threaded tube and internally threaded stator. I think that having got this far I may go for it and take out the engine as Colin suggested so I can check the rest of it out properly

Paul

[cbranni]

Sorry Paul, I got confused (old age) early stators have a plain hole that the breather tube fits into, the later stator has a threaded hole for the bolt through the crankcase but still breaths through same hole behind engine.
End float ...........my thinking is there has to be end float in the crankshaft, so with the alternator rotor removed you have .020 movement between the timing side flywheel and the timing gear, with the rotor on you tighten the nut this pulls the whole crank towards the drive side, this then clamps up the bearings tight against the flywheel, as engine gets hot any expansion goes towards the timing side.
The timing side bush is shaped like a top hat, the larger dia is inside the crankcase, and the flywheel runs against this large dia and as I quoted early there must be end float, I wonder why you have shims behind the timing gear I have not seen those before, not in the spares list either.
Just a thought......
If your breather tube is loose in the stator when you split the cases you could heat the end of the tube put a centre punch in the hole and hit it, this will enlarge the end and you will have a better fit, it may be a bodge but..................

Colin