My new bottom yoke fresh off the CNC mill:
After some dimensional/fitting checks all ok and off to Mikey with some other parts for polish/black anodising.
After my first real outing i appeared to have a huge oil leak from the cam chain tunnel, head barrels joint. I suspected the nitrile seal has got pinched during assembly, so off with the head and this is what ive found:
A bit more than a pinch!
It appears that some clown (me) has neglected to de-burr the edhes of the seal recess in the barrels after we did a skim after the liners were installed. How did i miss this!! So out with the die grinder, rags filling the tunnel and Henry on full suck:
Hopefully that will fix it and good job i had a spare seal.
Now on to the starter assembly saga:
When i first tried starting the engine all was fine and the bike fired up straight away albeit slowly as the engine is very tight with new rings/liners. Fast forward a few weeks and i started having problems with the main ring gear spinning on the crank and not engaging the clutch. On inspection it turns out that the problem is multi-fold:
I have the plain (non-keyed) rotor fitted to the old style keyed crank. This crank only has an M8 retaining bolt in the end rather than the M10 on the non-keyed crank. You cant get enough torque on to the M8 bolt to hold the rotor to the taper without a key in there.
I also discovered that there should be a rubberized washer between the ring gear and the main bearing on the crank. There was none on my bike and no mention of it in the Haynes manual. No surprises there then. The function of this washer is to create some friction between the ring gear and the bearing face to stop the gear free-wheeling. The washer comes in 3 different thicknesses 6.3/7.3/8.3 mm. But as of now i have not been able to find a new of even used washer anywhere. So i decided a bush fix was in order at this point if only temporary.
I did a measure up of the gear and gap (tricky) and worked out that a 35mm ID lip seal with the garter spring removed and the centre cut out may fit and provide the necessary friction:
The OD of the ring gear register is 35.5 mm so the remaining inner lip of the seal fits just right with a bit of persuasion and i got seals in 6,7 and 8 mm thickness although they all have slightly different OD's but all within the OD of the main bearing so they should locate ok.
I tried the 6mm first - little friction offered and it still slips< then the 7mm - better, then the 8mm which was too thick and caused the ring gear to continue to spin the starter motor once the engine fired - bizarrely!
So the 7mm, mummy bear it is.
Now to stop the rotor spinning on the crank. I put out a call and KeithZ1R graciously offered to do a rotor swap as he had a keyed one he was willing to let me have. On removing the rotor from the clutch i noticed 2 things; The retaining bolts were loose and the threads in the rotor were ovalled:
Bollocks!
I tried torquing up the bolts and they were fine and held well after running a tap down to the bottom. Keith was fine with this so the swap went ahead - Cheers Keith
Once i had the keyed rotor i procured an appropriate woodruff key from HPC gears and fitted the starter clutch to the keyed rotor. At this point i noticed that the pressed steel plate holding the rollers in laterally has been contacting the ring gear face and the plate was not flat but was splayed outwards and catching the gear. I know what i'll do, so i panel beat it all flat again. As i was doing this the thought crossed my mind that the plate had been bent out purposefully by a previous owner as it may have been impeding the movement of the rollers and sure enough when i torqued it all up 2 of the 3 rollers were locked solid. Bollocks!
At this point i went to the pub.
I ordered a new clutch assembly, a new needle roller bearing (irregular size) and a new 7.3 mm rubber washer from CMS. When they arrived as suspected the bearing and the rubber washer were the ones for the later engine design and did not fit. Oh well i need these for my race bike so they go into the parts bin. But the clutch does fit albeit without the locating dowel feature and i can tourue it up to specs fine with the rollers free. I now have 2 sets of spare rollers, springs and guides for some reason?
So time to put it all together and it works!
Or at least it did for a while, but now slips especially when a cold day. The rubber on the edge of the lip seal is very thin and this coupled with contraction of the rubber when cold allows the friction to be lost.
Double Bugger!
Now it seems the only way to really fix this is to obtain a proper rubber washer as this has plenty of rubber in contact with the bearing face and the steel part is only a flat washer.
So if anyone has a spare (any thickness) i would be most grateful even if its used as i can shim it little if required.
Its one of these with a 35 mm ID: