Author Topic: Engine blown - Cylinder spigot fractured  (Read 10502 times)

Online chaterlea25

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Re: Engine blown - Cylinder spigot fractured
« Reply #90 on: 16.12. 2011 11:01 »
Hi All,
If the cylinder is correctly sized and the liners fitted properly there should be no problems!!
Where the liner runs through the spigot it should be just a push fit  (no interference fit)
As the liner is always hotter than the cylinder block it will stay tight
As mentioned in another thread modern adhesives are magic *ex*

Going back a few posts, Mark Parker mentions oversize A65 exhaust valves
Does anyone (Mark) know where I could get these from????

John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline 1660bob

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Re: Engine blown - Cylinder spigot fractured
« Reply #91 on: 16.12. 2011 11:02 »
My barrels are sleeved back to standard, lucky me, or am I ....- the first thing I saw on stripping the motor was a nice big crack in the spigot.It seems to me that A10 barrels are short of "meat" to begin with, borne out by the mod to later thicker flanges.Boring and sleeving an already marginal design is i think, pushing ones luck at least and borne out of desperation. There is almost bound to be a slight difference in expansion in the two materials surely, however small, it can`t help matters.I couldn`t enjoy riding the bike knowing that lumps of brittle, cracked cast iron were poised ready to fall into the whirling  crank assembly....... we need new barrels, either cast as original, or alloy with liners. How aboutit Santa? ;) 

Online BSA_54A10

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Re: Engine blown - Cylinder spigot fractured
« Reply #92 on: 16.12. 2011 11:30 »
The barrels are plain grey cast iron
So when you get them sleeved you specify grey cast iron sleeves.
Cast iron usually expands at the same rate as cast iron so there should be no problems caused by different expansion rates
Cast iron sleeves are a little more expensive than steel sleeves.
If you want to be real choosy then ask for spun cast, fine grained cast iron sleeves as these have a better grains structure than standard cope & drag castings.
As for spigots cracking, more likely causes are resonant frequency vibrations, sloppy assembly work, impact from the conrod.
The spigot end of the barrels does very little work
Bike Beesa

Offline Mark Parker

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Re: Engine blown - Cylinder spigot fractured
« Reply #93 on: 16.12. 2011 12:56 »
   The valves I use in my A65 are cut down Jaguar 6 valves, they are cut shorter to A65 length and new collet grooves cut, rather than welding hardface on the tappet end I just fit hardened lash caps. The Jaguar exhaust valves are too big so I have the heads turned down to 39mm, it still leaves seat area. The inlets are ok at 44.5mm but usually need cutaways in the pistons enlarged. The ones I use are black nitrided, and can run quite close in a k/lined guide. Sometimes the cast in inlet seat is not well lined up with the valve and needs a new seat fitted so the inlet isn't trying to seat on aluminium, most heads are ok. If you run the big valves in a 650 or 750 with large carbs 38mm for eg, it can run sweetly over a wide rpm range so long as the header dia stays std, if you up header dia you can up power but you may not get it till 4,500 -5,000 though it depends on the pipes and how you port the head. The latest head on my 880 motor has "D' shaped inlet ports, the floor of the oversize port is filled and flat as it turns under the guide. All it does is fill a deadish flow area, I don't think it flows less, yet certainly goes better with the increased gas speed bringing power in earlier.
   An alloy block in my opinion is much better with Nicasil than a liner.
Had a nice A10 once, :( now only have the power egg child A65 :(

Online chaterlea25

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Re: Engine blown - Cylinder spigot fractured
« Reply #94 on: 16.12. 2011 22:54 »
Hi All,
Thanks for the info on the A65 valves etc,
I have a long term project with a 1925 Chater Lea that has an ohv Blackburne engine, It had been bodged beyond all recognition inside the engine  *sad2*
Anyway it turns out that A65 valves are almost identical in length and head size to the Blackburne
The A65 stems are smaller so I made new guides to suit,
However the standard A65 exhaust valve sits very near the inside of the valve seat, which is why I am looking for one a couple of mm bigger!
I have a couple of "Goldie" valves which I can turn down and the radius tool for the groove,
As you say hardened caps will sort the valve tips
I was looking for an easy way out  :!

On the gas speed subject, I used to have a Morini 3 1/2,  Those things really flew with brilliant handling  *smile*
Apparently the designer had a major "thing" for gas speeds
Heron heads, that had what looked like "small" ports
The exhausts pipes were double skinned as well

John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Duncan R

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Re: Engine blown - Cylinder spigot fractured - update
« Reply #95 on: 30.12. 2011 15:51 »
Hi All,

Just split the cases - large lumps of spigot and assorted shrapnel all in the bottom end.

Initial inspection seems promising, main bearing bush undamaged, rods still straight, crank journals appear untouched, camshaft also OK. I think it was an instant break so engine locked and there was no time for any of the debris to get round the engine.

Obviously it will need a thorough cleaning and everything blown out and inspected properly, so hopefully once some cylinders  and new pistons are found It can go back together.

Happy New Year

Anglo - Indian A7SS (Actually is a 650)
Kawasaki ZZR 1100