Try our new info resource - "Aladdin's Cave" (Main menu)Just added a separate link to Ash's Dropbox thread (shortcut)
If the pin hole is elongated, it may have been caused by the bearing spinning in the case as some stage in its life. Can you see any evidence of where the bearing may have spun?
Is the thrust washer behind the needle bearing Ted, there should be a 20mm washer between the bearing and the gear.
Hi Ted,I just spotted your post as I was about to post a query on the roller pins of the gearchange positive stopper. (Soon)I have my crankcase halves assemmbled and have been measuring the 5 mainbearing borings for size.Just been in my garage and checked this shaft for end float - mine is solid with no movement between the shaft and the inner bearing, but if I push in and pull out firmly it will move the outer bearing in the casing and shaft about 0.5mm, which appears to be the side movement in the half circlip and its groove.Hope this helps. RegardsDennis
Hi Ted,This is the overhang on my bearing FWIW. Dennis
"It might be both bearings are not as planted as the design suggests. Perhaps constant gear changes on a revvy little 400 engineb takes its toll on the bearing fittings. Very useful info thanks. Ted"Typically of bikes in general and certainly in these engines, there's essentially no real thrust load of any significance with all the gear teeth straight cut. Clutch operation is the largest (which should be opposed by the clutch assembly clamping it's shaft on that principle bearing) but the rest of tolerancing is to facilitate accurate movement and controlling engagement of the dogs and their relationship to the shift drum along with it's forks. Insignificant load that would cause wear though in that direction. Even the crankshaft has no effective thrust bearings as it's not subjected to that force.In a car with helical cut gearbox and clutch pushing directly onto crankshaft end, then they need to be mitigated, but on these it's just positional accuracy without much force that could cause components to wear.
Are the half rings proper half rings? We have had numerous engines through here where someone has been in them in the past and they have used half of a piston ring as a substitute.