Author Topic: Re: A10 timing  (Read 570 times)

Offline Bess

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Re: A10 timing
« on: 20.10. 2018 10:03 »
Hi,
    I have my engine lower end built ready to fit to frame, the cylinder head and primary hasn't been fitted, I am fitting a belt primary.

I figure marking the drive side pulley with the correct timing marks at this point would be prudent. Has anyone done this or can help with advice?

Many thanks...

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Re: A10 timing
« Reply #1 on: 20.10. 2018 10:28 »

 Yeah-seems like a good idea if you index it to a constant reference on the crank, like the split-pin holes...except that depending if you have a cushion setup, which may render it variable (unreliably useless)...I have a degree disc setup behind my cush spring, but don't really use it except as a reference when I have the cover off- maybe you'll run an open primary?

 Muskrat also has a degree disc the same, but has it setup more usefully I think...and will be able to enlighten you better
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
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Offline Bess

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Re: A10 timing
« Reply #2 on: 20.10. 2018 11:19 »
Hi Dutch,
             Thanks for your input.

I will not be having a cushion and the primary and will have a cover with vent holes so I will be able to see the index. My A65 has such a mark on the alternator rotor so I was hoping I could do similar.

What degree before tdc should I use on a A10, I will be using premium petrol.

Thanks...

Online RichardL

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Re: A10 timing
« Reply #3 on: 20.10. 2018 15:42 »
Bess,

Some general number for degrees BTDC could be suggested but, really, it changes based on cam type, compression, head type and, I think, valve size. You should provide this info and some more informed suggestions will, no doubt, be offered. In any case, I don't like the idea of a single timing mark because it kills the play-around factor.

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.

Offline baz

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Re: A10 timing
« Reply #4 on: 20.10. 2018 16:05 »
Hi Dutch,
             Thanks for your input.

I will not be having a cushion and the primary and will have a cover with vent holes so I will be able to see the index. My A65 has such a mark on the alternator rotor so I was hoping I could do similar.

What degree before tdc should I use on a A10, I will be using premium petrol.

Thanks...
are you not going to use a cush drive? dont forget a belt is less forging than a chain that is running in oil with a minute cushion of oil on every pin,,, early commandos had no cush drive and thats like being kicked up the idiot every time you put it in gear, could you not fit a triumph clutch to it? cheers

Offline Bess

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Re: A10 timing
« Reply #5 on: 20.10. 2018 16:17 »
Hi,
    I don't want a cush drive and I don't mind having a single timing mark.

The cam is standard, the compression ratio is 8.25:1 with a alloy head.

Best wishes...

Online RichardL

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Re: A10 timing
« Reply #6 on: 20.10. 2018 16:56 »
Bess,

The first link kind'a gives an example of fun with experimenting.

The second link (which I just rediscovered) is a factory dyno sheet for a '58 A10. I found this very interesting. In this case, 34 degrees. If you search around the forum you will find recent dyno tests, mostly (or all) by member "orabanda", so you could search for dyno posted by orabanda.


https://www.a7a10.net/forum/index.php?topic=3747.msg25975#msg25975

https://www.a7a10.net/forum/index.php?topic=2277.msg14617#msg14617

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.

Offline Bess

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Re: A10 timing
« Reply #7 on: 20.10. 2018 17:32 »
Hi Richard L,
                   Thanks........ *smile* *smile*

Online chaterlea25

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Re: A10 timing
« Reply #8 on: 20.10. 2018 17:48 »
Hi Jess,
Not having a crush drive is a bad idea in my opinion and experience
If you are using a Hayward conversion then a 3 or 4 spring clutch inner drum will provide a cushion
I have a BNR conversion sitting waiting for the next project. It was removed from a gold star after relatively small mileage
The engine pully is worn , especillly badly where the power pulses put strain on it
I am intending to up the gearing on the project so a new pulley will sit on a cush  drive
There is no need to vent the primary unless  the bike is going racing
It just allows road dirt to get in the works.
 John
1961 Super Rocket
1963 RGS (ongoing)

Online JulianS

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Re: A10 timing
« Reply #9 on: 20.10. 2018 18:20 »
I use 35 degrees BTDC  on my A10 alloy head + 356 cam + GPM high comp pistons. Runs fine on standard unleaded.

Offline Bess

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Re: A10 timing
« Reply #10 on: 20.10. 2018 18:23 »
Hi Julian,
             Thanks......

Offline Bess

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Re: A10 timing
« Reply #11 on: 20.10. 2018 19:08 »
Hi chaterlea25,

Thanks for sharing you experiences.

After research and advice from many users I'm using a Bob Newby clutch, he suggests venting the case either by leaving off the rear sliding plate or sandwiching 'O' rings between the outer and inner case. I'm not keen on these solutions as dirt could contaminate the system.

I have a old damaged case which I am going to adapt to ensure the inner case is held firm without oil leaks from the 3 front 5/16" screws, these will be left in place when the outer cover is removed. The outer case will have ventilation protected by a either a filter or very fine mesh lightly oiled to hold back solids and deter liquids. At the moment I'm not concerned with the lack of cush, other riders with a Newby system don't seem to mither.

Best wishes...

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Re: A10 timing
« Reply #12 on: 20.10. 2018 20:42 »
G'day Bess.
I have my front pulley marked wit TDC, 30, 35 and 40 degree marks. I have a mark on my outer cover to use a strobe timing light. The pulley and crank are marked to assemble in the same spot every time.
You could mount a pointer to the two inner case bolts rear of the crank.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
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Online duTch

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Re: A10 timing
« Reply #13 on: 20.10. 2018 21:06 »

 
Quote
...What degree before tdc should I use on a A10, I will be using premium petrol.......

 Yo Bess- best I could give is somewhere between one end and the other of a bit of string - depending how long it is....general consensus is around 30˚-35˚ or so, but I think that's now covered...
 Regarding the split pin hole; I've noted on the couple I have that the hole(s) are at 90˚ to the crank throw, which may be of some use.... *idea*
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 Bess

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Re: A10 timing
« Reply #14 on: 20.10. 2018 21:29 »
Hi muskrat,
                  Cool, exactly what I was looking for. With the other deg. setting suggestions I think I'm on the right track. I like your cover cutout, do you have contamination issues?

P.S. I think I note your oil filter arrangement, if it is a oil filter can you give more info?


Thanks again...