Author Topic: timing wheel?  (Read 5686 times)

Offline emilios

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timing wheel?
« on: 15.01. 2010 16:58 »
Hi
Im just wondering where and how to put timing wheel to set ignition timing..
1956 BSA A10 Plunger
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Offline MG

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Re: timing wheel?
« Reply #1 on: 15.01. 2010 18:45 »
Hello emilios!

You can put the timing disc on either end of the crankshaft and tighten it with a suitable nut.
With everything assembled (oil pump drive, primary cush drive) I have also fitted it to the outer nut of the primary cush drive with simple double-sided adhesive tape. I usually make a pointer out of a piece of wire and tighten it to the engine casings with one of the cover screws.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline emilios

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Re: timing wheel?
« Reply #2 on: 15.01. 2010 19:09 »
thanks MG...
I set ignition timing without head before a week or so....but i forgot to check both cylinder..
So i will check tomorrow but i dont want to take head off...so i will do it with the timing wheel..
I looked around some topics and found out that 3/8 is 35.5 degrees...
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Offline MG

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Re: timing wheel?
« Reply #3 on: 15.01. 2010 19:41 »
With the iron head models I don't use more than 33 deg, otherwise they tend to ping under load.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline emilios

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Re: timing wheel?
« Reply #4 on: 15.01. 2010 19:48 »
Yes but i put hc pistons and thats what the supplier set..3/8
???
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Offline MG

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Re: timing wheel?
« Reply #5 on: 15.01. 2010 19:57 »
Maybe the HC pistons were designed for the alloy head models?
36 deg BTDC would be the timing figure for the Rocket.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline emilios

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Re: timing wheel?
« Reply #6 on: 15.01. 2010 20:05 »
Do you thing that HC pistons will cause any problem to my iron head engine? or if i stay down to 33 deg will be ok?
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Offline MG

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Re: timing wheel?
« Reply #7 on: 15.01. 2010 20:07 »
I'm running the iron head GF on 9:1 without any problems (@33 deg). Just found it tends to ping when advanced further than 33 deg.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline emilios

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Re: timing wheel?
« Reply #8 on: 15.01. 2010 20:22 »
Ok so im going to 33 deg tomorrow morning..
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Offline emilios

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Re: timing wheel?
« Reply #9 on: 16.01. 2010 12:30 »
Today i checked if both cylinders fire the same time...and i found one at almost 34 deg and the other almost  26 deg...
After 2,3 attempts i have both cylinders firing 32 deg...
I didnt run bike far...only half mile or so but i notice much less vibration and much smoother engine...
im planning to do a 50mile trip tomorrow to see how it goes...
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Offline MG

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Re: timing wheel?
« Reply #10 on: 16.01. 2010 13:42 »
Sounds good, congratulations!
32 deg is definitely OK.

Enjoy your trip tomorrow and let us know how it went!

Btw: What was the problem with the misfiring we discussed in the other thread? Faulty pickup?
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Offline emilios

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Re: timing wheel?
« Reply #11 on: 16.01. 2010 17:05 »
I put new pickup and new plug caps...but it should be cap cause when i checked them with an multimeter they showed huge resistor....
1956 BSA A10 Plunger
1954 BSA B31 Goldstar Replica
1970 Honda cb750K0 project
Cyprus

Online orabanda

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Re: timing wheel?
« Reply #12 on: 17.01. 2010 00:24 »
Running my 51 GF on a dyno showed that 30 BTDC was the best setting

Online Brian

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Re: timing wheel?
« Reply #13 on: 17.01. 2010 00:48 »
Do any of you mathematical geniuses happen to know what 30 or 32 degrees is in distance before tdc. I run my A10's on 5/16" BTDC and that seems to be about right, go well and no pinging. Thats with iron heads, maybe the alloy ones would tolerate a touch more advance, maybe not.

Offline olev

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Re: timing wheel?
« Reply #14 on: 17.01. 2010 02:00 »
Brian, Take a deep breath, get a glass of your coonawarra red and a calculator.

T = L + R X (1 - CosA) -   the square root of ( L squared - ((R X SinA)squared))

where
T = distance BTC in mm
A = timing in degrees
L = conrod length in mm
R = engine stroke in mm divided by 2

You will notice I havent worked out how to do the square root or squared symbols
cheers