Engine dismantling questions

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Re: Engine dismantling questions

Postby clanger9 » Wed Oct 04, 2017 6:56 am

I thought the same thing at first, but I have another CSR crankcase here and it has the same hole.
Interesting that yours has a small drain hole directly back to the tank.

Presumably a mod to improve oil drain by providing a bigger hole?
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Engine dismantling questions

Postby Ozmadman » Fri Oct 06, 2017 1:10 am

clanger9 wrote:I thought the same thing at first, but I have another CSR crankcase here and it has the same hole.
Interesting that yours has a small drain hole directly back to the tank.

Presumably a mod to improve oil drain by providing a bigger hole?

And dropping the oil onto the big-end which can only be a good thing
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: Engine dismantling questions

Postby clanger9 » Fri Oct 06, 2017 6:52 am

On a related note, does anyone know how oil gets to the drive side main bearings? There doesn't seem to be any specific oil supply.
I'm wondering because the inner main bearing on my engine is completely destroyed, though there is little else wrong with the rest of the engine (other than severe wear on the timing side bronze bush).

Here's a picture:
IMG_1689.jpg

The rollers were all there, but one fell out when I dismantled it. You can see the rollers are all shot and the inner track is rough, although oddly the outer track is undamaged. Anyone care to speculate on what could have caused this?
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1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Posts: 2309
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Re: Engine dismantling questions

Postby Ozmadman » Fri Oct 06, 2017 2:58 pm

Just old? cheap bearing fitted? lack of oil in the past?( easily done if the P.O hadn't kept a close eye on the level) change both bearings and fit two of the roller type like your knackered one (early models had ball bearings) the recommendation for fitment of the inner bearing is to make sure the outer track stays secure in the casing by centre punching the casing is 3 positions once the other bearing, breather stator and inner track has been fitted (maybe these days some loctite will do the same thing)
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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