Cylinder angle of turn

[bsa-bill]

ON a PC it's alt+ 0178 I think, however by the time I've done that I could have typed "degrees" (or something close  )

[a101960]

ON a PC it's alt+ 0178 I think,

Bill you can use ALT+ 0176 or ALT+ 248 either will do it. What a sad life I lead.
John

[KiwiGF]

Heh Dutch, my barrel base was not even flat....it needed over 020 milled off to make it flat, luckily it was a thick flange type. Now not so thick.....

My engineer spent quite a while figuring out the best way to ensure everything lined up as well as possible, and found out that the boring/honing work and top face machining work were most likely referenced off the top face and not the bottom base of the barrel........

[duTch]

 

My engineer spent quite a while figuring out the best way to ensure everything lined up as well as possible, and found out that the boring/honing work and top face machining work were most likely referenced off the top face and not the bottom base of the barrel........

 Yo Kiwi, I guess it's the obvious thing to do with out thinking about it. It likely explains why I have a difference of a few thou from top of pistons to top of barrel- but as I said earlier, I'd read a discussion(maybe yours) about the boring method, and may or may not have measured head face to flange, but put it down to the rods being a bit whacko anyway....so changed them and got on with it..  ...

 I guess the obvious fixit, is to set the barrel on the flange and bore it and skim the head interface at the same time (if it can be done on the same machine)

 Started this a couple of hours ago...better send it before I forget...

[KiwiGF]

Heh dutch, the machinest made up a solid ally mandral which fitted inside one bore exactly and which had a perfectly square end which was bolted to the mill bed abd the barrel slId over it.....then he machined all round the barrel base....thus making the base 90deg to the bores....

 the cylinder face was left "wrong" as he felt it woukd make little difference fixing that up

he had to make the mandral sightly tapered to fit the bore perfectly 

[ppanichelli]

wow, this forum is amazing! that was my first post (after the introduction) and it generated a really cool interaction.

Thanks so much to everybody for the answers!!! Also to the funny ones

Well, in order to bring some additional confusion, I could mention that after reviewing the cylinder with the mechanic he noticed that the barrels below the base had one side 2 mm wider than the opposite side.

This fact remarks that someone was wrong regarding the barrels angle. We assumed that the the boring machine was set 90°, which could give some credit to the version of barrels not at 90°. Or it also could be that they swallowed the fake version and ruined the cylinder.

So far I only have a collection of broken cylinders and a forgotten bike that doesn't roar anymore

[edboy]

surely the way to go forward is another set of barrels. i have seen a10 barrels come up on u.s. ebay which must be within postage distance.  barrels are expensive and probably the rarest part of the engine  so make sure you buy a good low milage set.

[duTch]

 

Heh dutch, the machinest made up a solid ally mandral which fitted inside one bore exactly and which had a perfectly square end which was bolted to the mill bed abd the barrel slId over it.....then he machined all round the barrel base....thus making the base 90deg to the bores....

 the cylinder face was left "wrong" as he felt it woukd make little difference fixing that up

he had to make the mandral sightly tapered to fit the bore perfectly 

                                                                   

[olev]

hmmm,
The bores have to be at right angles to the centre line of the crank lengthwise.
however i'm not so sure about the 90° bit when you are looking from the side of the motor.
if you google 'cylinder offset from crank' you will find some engines do not have the bore directly over the crank.
At top dead centre you can push the piston down with your finger due to this offset.
Maybe this is what Panni's mechanic was referring to.
I have a vague idea musky talked about offsets once. (pistons maybe ??)
cheers

[duTch]

 Yo Olev, I'm pickin' up what yo're puttin' down, and it's not on my boot....I think Musky was talking about piston/gudgeon/wrist pin offset..but I'll let him sort that out when he sobers up... ...

 ...for the rest of it I'll have to draw some artwork on the back of a drink coaster...(might've finally found a use for them )

[edboy]

i m a little lost on this one as i thought all modern  boring bars bolted to the cylinder head surface and relied on the manufacturers machining being correct at the base flange.

[KiwiGF]

Unfortunately I sold an a7 barrel with standard bore for $200 a while back, in New Zealand I thought myself lucky to find a buyer! 

Is this barrel being sold by boa any use?

http://en.vintage-motorcycle.com/index.php?language=en&site=4&pid=369&id=9603&limit=0