Author Topic: Engine Bush Reaming Setup  (Read 1483 times)

Offline magicflem

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Engine Bush Reaming Setup
« on: 06.06. 2017 04:54 »
The engineer I am using has line bored/reamed my crank bush and the cam bush, but not aligned them to the idler pinion between (cogs don't mesh, just jam) - I don't know if the magneto cog will mesh either.

In what order should he have bored/reamed?

I would have thought:
1st. line bore crank shaft using roller bearing (drive side) as setup for the brass bush on timing side. This has to be centred, at right angle, parallel etc, and everything else works from this setting. 
2nd. fit magneto with cog.
3rd. line bore cam and idler to "mesh with" magneto and crank cogs.

Am I right?


1930 BSA B30-3 Side Valve Girder (being restored)
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Online KiwiGF

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Re: Engine Bush Reaming Setup
« Reply #1 on: 06.06. 2017 05:58 »
This is very odd. Normally I reckon just the timing side bush is line bored without consideration of the timing gears etc, and yes one "reference" is ideally the cylinder base, I'm not sure on the other axis but the journal housing should do, and if used should near enough maintain gear mesh.

On the cam side, I would expect the rhs journal housing to be used as the reference and any misalignment to be compensated for by boring the lhs bush off centre. Again this job is often done without consideration of anything else. This job is tricky for an engineer and there might be a temptation to bore the rhs bush off centre, not lhs?

Are your cases non matched? This can cause an engineer a few issues to resolve if so.......on mine even the barrel bottom face was curved!

Non related possibly, but I bought a new ally mag gear and had quite a bit of fettling to do to make it mesh correctly.




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Online Clive54bsa

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Re: Engine Bush Reaming Setup
« Reply #2 on: 06.06. 2017 15:15 »
You may have needed one of these, if you can find it.


'54 GF,  '61 SR

Offline coater87

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Re: Engine Bush Reaming Setup
« Reply #3 on: 06.06. 2017 16:03 »
How bad is the meshing, is it just "grindy" or is it actually jamming solid?
Central Wisconsin in the U.S.

Online chaterlea25

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Re: Engine Bush Reaming Setup
« Reply #4 on: 06.06. 2017 19:35 »
Hi,
Quote
The engineer I am using
has made a Boll*x of the job  *problem* *angry*

It is unusual to have to renew the cam bushes, they seem to survive all sorts of blow ups and neglect and still be ok
Check the magneto to cam mesh and see if thats ok?
If it is, and the cam spins freely with the cases bolted up,
I would  remove the crankcase idler bush and see if its concentric inside to outside or not ?
This is the easiest to remove and check , it may need "adjusting"
The inner timing case  idler bush finally must be concentric in its bore with its partner in the crankcase
The original jig worked the cam bushes from the timing side, so I would have followed that method

2 cents worth
John







1961 Super Rocket
1963 RGS (ongoing)

Offline Zander

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Re: Engine Bush Reaming Setup
« Reply #5 on: 08.06. 2017 11:19 »
After speaking with one of our knowledgeable members I decided to sort of line bore my new plain bush, locating the reamer accurately from the drive side bearing outer.
By a complete stroke of luck some time ago I was given a brand new adjustable reamer and a large lump of brass which was used to make the bush / reamer guide.
I also made a plug gauge with three progressive diameters to assist in getting the correct size.
Long story short, it seems to have worked; on assembly, the crank turns smoothly, and a light covering of engineers blue on the journal showed up its evenly in the bush. Obviously, proof of success or not, will only show when the engine is run, and as you can imagine, I'm crossing everything I've got!  On the crankshaft drive side where the shims locate, I noticed a ridge which was preventing the shims from sitting flush, so I also set the crank up accurately in the lathe, removed the ridge and lightly skimmed the web to provide a good, smooth surface.  Preliminary assembly is showing end clearance at 0.0015".  Final assembly will start when I get the Wellseal I've just ordered.
'59 GF

Offline terryg

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Re: Engine Bush Reaming Setup
« Reply #6 on: 08.06. 2017 11:38 »
Congratulations. My only attempt at using an adjustable reamer, a very long time ago, resulted in a total horror. Well 2 horrors in fact - small end bushes.
Perhaps one day I'll have the courage to try again.
Terry
'57 'SR', '59 SR, '63 RGS

Offline Zander

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Re: Engine Bush Reaming Setup
« Reply #7 on: 08.06. 2017 11:53 »
As mentioned, I was sort of encouraged to give it a go by someone who had done it himself.  Prior to biting the bullet, I approached a number of engineering companies that listed line boring as a service, but they all referred me to some-one else who didn't want to do it either, so the die was cast.  I knew I was risking an expensive bearing, but I also knew I wasn't going to bugger the cases up, so I took the chance. It remains to be seen if it pays off.  When I bought the bike, I expected to be able to use it from day, but it hasn't turned out that way, and one thing leads to another...... my trouble is I can't leave anything alone - hence machining the crank web and clutch centre housing.
It's a disease, I'm afraid.  A bit similar to believing that one Moto Guzzi is enough!
It isnt😄
'59 GF

Offline duTch

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Re: Engine Bush Reaming Setup
« Reply #8 on: 08.06. 2017 12:00 »

 
Quote
On the crankshaft drive side where the shims locate, I noticed a ridge which was preventing the shims from sitting flush, so I also set the crank up accurately in the lathe, removed the ridge and lightly skimmed the web to provide a good, smooth surface.  .............. 

 I really think you should not have done that. .. *bash* *bash*
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Online RichardL

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Re: Engine Bush Reaming Setup
« Reply #9 on: 08.06. 2017 12:44 »
Dutch,

I'm assuming Zander means he just skimmed at the shim landing area, not the whole web.

Zander,

Am I correct?

Richard L.
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Offline duTch

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Re: Engine Bush Reaming Setup
« Reply #10 on: 08.06. 2017 13:08 »

 
Quote
I'm assuming Zander means he just skimmed at the shim landing area, not the whole web.

 The way I read it is that zander skimmed the ridge back to flush with the web- maybe I was wrong, and it was just a skim to make it still a raised landing with no run-out  *????*
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline Zander

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Re: Engine Bush Reaming Setup
« Reply #11 on: 08.06. 2017 13:25 »
Yes- I removed the ridge and skimmed the shim locating surface which cleaned up within a couple of thou.   The crank shaft was clocked on both journals and both ran within half a thou at the start of this operation.  I was happy with that.
'59 GF

Offline JulianS

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Re: Engine Bush Reaming Setup
« Reply #12 on: 08.06. 2017 13:30 »
If the web is machined I think the main point is not to remove the stress relieving radius between it and the drive shaft and introduce a possible fracture point.

Offline Topdad

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Re: Engine Bush Reaming Setup
« Reply #13 on: 08.06. 2017 15:05 »
Thanks Julian, now I think I understand why radius is important.
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Offline Zander

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Re: Engine Bush Reaming Setup
« Reply #14 on: 08.06. 2017 17:23 »
I stopped short of the radius for the reasons outlined.
'59 GF