Author Topic: Engine blown - Cylinder spigot fractured  (Read 9976 times)

Offline WozzA

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'51 Golden Flash Plunger
'57 Golden Flash Swingarm

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Offline olev

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Re: Engine blown - Cylinder spigot fractured
« Reply #76 on: 09.12. 2011 08:29 »
hmmmm,
A lot of drive side cases show signs where the rod exited.
Somehow I don't think a red hot top end is going to help reduce this habit.
cheers

Offline Mark Parker

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Re: Engine blown - Cylinder spigot fractured
« Reply #77 on: 09.12. 2011 09:05 »
Muskrat, do you have some base gaskets to compare, A65 - A10. You are welcome to come visit anytime.
   The way I made my A65 cyl was to get an old std cyl and knock every second fin off it, that allowed me to easily fill between the fins and thicken it to the shape I wanted with body filler, it had to be built up everywhere a bit because when its cast there is a little shrinkage. Then I took casts from it and from them made sections in F/glass resin, those sections I then attached to boards and painted with a type of paint the treated sand does not stick to. I made it pretty simple with only 3 patterns; front, back and underneath. There is no air passage between the cyls because in alloy its unnecessary, stronger and simpler to make.

So to make patterns this way, you would need an old A10 cyl that is no good, even if it had a broken flange that could be stuck back together would be ok. It would be a bit harder to do keeping all the fins but making something from scratch would be more difficult I expect.
Mark
Had a nice A10 once, :( now only have the power egg child A65 :(

Online RichardL

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Re: Engine blown - Cylinder spigot fractured
« Reply #78 on: 09.12. 2011 12:06 »
Mark,

That's an amazing bike, engineeringwise, lookswise and I, presume, in performance. The barraels are a great accomplishment and extremely interesting.

Richard L.
Plan on signing up for the world-wide 2017 DISTINGUISHED GENTLEMAN'S RIDE on September 30, 2018. Watch website at https://www.gentlemansride.com for details.

Online muskrat

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Re: Engine blown - Cylinder spigot fractured
« Reply #79 on: 10.12. 2011 10:27 »
 G'day Mark,
                 might have to wait till the terrorists I mean tourists go home. Try to stay off the roads this time of year. But if I go out I give'm a floggin'.
 *evil* *fight*
 A few scans of gaskets. 1 is A10 blue over A65 black, 2 is A65 green over A10 blue, 3 is A10 over A65, 4 is A65 over A10. The head gaskets have 4 holes the same. The circles on the blue A10 base gasket is for my through bolting which are close to the A65 side holes.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
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Online muskrat

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Re: Engine blown - Cylinder spigot fractured
« Reply #80 on: 10.12. 2011 12:56 »
Bugga, forgot to add scans.
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
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Offline MG

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Re: Engine blown - Cylinder spigot fractured
« Reply #81 on: 10.12. 2011 14:20 »
Looks like the A65 crankcases are a bit wider and offer some more space for larger bores/spigots???
Other than that, seems not too far off. Is the distance between cylinder centres the same? Hard to tell from the head gasket pics.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

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Offline Triton Thrasher

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Re: Engine blown - Cylinder spigot fractured
« Reply #82 on: 10.12. 2011 17:30 »
Maybe not too relevant, but new Pre-unit T*****h barrels are less of a problem. I suppose it's because you can make any 650 barrel, 1950-1974 out of the same casting.

Anyway, casting and machining A10 barrels must be hardly rocket surgery.  Can't the Owners' Club commission some?

Offline Mark Parker

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Re: Engine blown - Cylinder spigot fractured
« Reply #83 on: 10.12. 2011 22:04 »
Maybe you could trace the bores from the A65 H/gasket onto paper and sit the A10 flange gasket in place and see how much room there is for the thickness of the spigots. I've had an A10 crank in an A65 so bore centres are not a problem.
Mark
Had a nice A10 once, :( now only have the power egg child A65 :(

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Re: Engine blown - Cylinder spigot fractured
« Reply #84 on: 11.12. 2011 09:17 »
 I remember one of my first race motors (A7) that I through bolted, I built up the cases mouth where I added the studs by about 2mm and just got the spigots past. Shed closed for the night but will do a little digging tomorrow.
 Got me thinking of a 75mm bore A10 is close enough to a 750 and with a A65 head  *eek* *smile* *work* *yeah*
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline Mark Parker

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Re: Engine blown - Cylinder spigot fractured
« Reply #85 on: 11.12. 2011 12:47 »
These are 76mm, would give 762cc if it's possible to fit, 75mm gives 742cc, around that size would be optimal I would think. A70 pistons have the better pin height.
http://www.shopevengineering.com/productdetail.htm?productId=-293797&catalogId=-2087&fpg=1
It could be set with less compression 10.5 - 1 might be a bit high. 9 -1  would be kinder on the old cranks. Even getting pistons made specially wouldn't be difficult. These type of forged piston are especially good value.
Mark
Had a nice A10 once, :( now only have the power egg child A65 :(

Offline MG

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Re: Engine blown - Cylinder spigot fractured
« Reply #86 on: 11.12. 2011 14:23 »
Pistons are no problem, I had these made for my CSR, cost me 750 Euros landed, for a set of 4 (minimum order), incl. rings and pins. Imho not bad value for forged, custom-made equipment, quality is excellent, and with some material removed on the inside also good weight-wise, and you can get them made to own specs.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

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Offline chilblayth

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Re: Engine blown - Cylinder spigot fractured
« Reply #87 on: 15.12. 2011 23:55 »
the original bsa cylinders were machined from the casting   , i had a pair of cylinders  resleeved by grampian motors in 1977 ?   approx ,  unfortunately i took too long coming up with the cash and he sold them on me  *sad2* so i cant comment on if its a sound solution !   but i remember looking at them and there was a small crack running down the barrel spigot on one side  which i didnt like the look of , personally i think there isnt enough metal on the lower spigots  coupled with the fact these original barrels are 50 yrs old  , when the liner gets hot it expands , i think at a faster rate than the original metal, !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
recipe for disaster  *sad2*

Offline KiwiGF

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Re: Engine blown - Cylinder spigot fractured
« Reply #88 on: 16.12. 2011 10:15 »
Well I've just had some thick flange lined barrels honed to suit some new STD bore JP pistons, they have ended up just 001 over the clearance JP recommend

The liners and old pistons had some scoring from a seizure but the liners had not moved, it never occured to me liners were a bad idea. I thought this was a standard solution once 060 over was reached and maybe even the liners could be bored -020 to prolong barrel life even further.

Fingers crossed the lined barrels I have last OK then!
New Zealand

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Online bsa-bill

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Re: Engine blown - Cylinder spigot fractured
« Reply #89 on: 16.12. 2011 10:21 »
The liners I had fitted were old Hepolite stock.
The shop that fitted them were quite happy to do so and you have to wonder would Hepolite have produced them if there was any doubt.
IIRC Tthe liners have to be bored after they're fitted to bring them to size and in line
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco