Author Topic: Timing Tool  (Read 1150 times)

Offline LJ.

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Timing Tool
« on: 24.08. 2018 11:21 »
One of these arrived today, any Good?? I would like to hear and learn of any tips that you can give in their use.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline a10gf

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Re: Timing Tool
« Reply #1 on: 24.08. 2018 11:59 »

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Online Greybeard

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Re: Timing Tool
« Reply #2 on: 24.08. 2018 12:14 »
The only problem I can see, and this has been discussed before, is that the plunger is not at right angles to the piston crown so the marking will not be accurate. This doesn't matter of course if all you want is TDC. I suppose if that tool was designed for our bikes it may have been graduated to take the plug angle into account.

Offline a10gf

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Re: Timing Tool
« Reply #3 on: 24.08. 2018 13:07 »
So my "tool" wins :O) it's 90 deg to piston.

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Offline bikerbob

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Re: Timing Tool
« Reply #4 on: 24.08. 2018 13:33 »
Everybody has their own way of setting the correct piston height and Greybeard is correct in what he says about the angle of the plug hole in relation to the piston crown, I did once measure the angle and draw it all out on paper and there is a difference in relation to the angle of the plug and the vertical drop of the piston. How I overcame this was to use an old plug break off the ceramics and modify the center of the plug to accept a 8mm dia rod, tighten the plug in the head then bring the piston up to TDC then using a junior hacksaw blade mark the rod take rod out put a decent groove in the rod using the junior hacksaw then measure your timing distance accurately from the bottom of the groove  put another groove in the rod so that your correct distance is to the bottom of both grooves when you set the piston at TDC take it down to the top of second groove this then compenstes for the angle of the plug hole. As I said earlier everybody has their own way and this works for me.  Also as an addition I was told many years ago that when setting correct height of the piston you should always take the piston down past the correct  level and then bring it back up to the correct mark this I was told eliminates any wear in the timing gears. In regard to the original post you only have to look at who makes it to make me doubtful look at the width of the timing grooves if you used the bottom of one and top of the other you could be off with your timing.

Online BigJim

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Re: Timing Tool
« Reply #5 on: 24.08. 2018 16:51 »
Hi LJ, I got one of these years ago. It has been very useful. There are so many worn out parts on my bike that i just glad it starts and runs and i'm sure my timing could be better but she runs at mo.  *smiley4*
Jamie,  Supporter of Distinguished Gentleman's Ride

Online Greybeard

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Re: Timing Tool
« Reply #6 on: 24.08. 2018 17:09 »
I 'aquired' this tool when I was working on Puch mopeds. It's not long enough to use on an 'A'

If anyone has a need for this let me know.

Offline Peter Gee

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Re: Timing Tool
« Reply #7 on: 05.09. 2018 19:39 »
I like BikerBob's idea..so what is the correct BTDC for an A7SS?

Online Greybeard

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Re: Timing Tool
« Reply #8 on: 05.09. 2018 19:47 »
...what is the correct BTDC for an A7SS?
I have the W. C. Haycraft, 'BSA Twins' book here. It says; A7 Standard 5/16", A10 Golden Flash 11/32", All sports type engines with High compression pistons, (7.5 to 1) 3/8"

Offline roadrocket

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Re: Timing Tool
« Reply #9 on: 13.09. 2018 19:51 »
I did what Bikerbob did, works a treat! The moving pin on my one is hexagonal, so I have different bikes' settings marked on a side each.
Otto in Denmark

Offline bsa-bill

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Re: Timing Tool
« Reply #10 on: 13.09. 2018 21:13 »
a handy tool for getting TDC, you can get a measurement by setting a rule up against vertically, might need thre hands tho
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

Offline jachenbach

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Re: Timing Tool
« Reply #11 on: 14.09. 2018 03:48 »
Why not just use a tdc finder and degree wheel? Using A10 stroke=84mm=3 5/16 inches=53/16 x 2 for a complete revolution, 3.4 degrees= 1/16". Don't recall what the advance should be in inches, but a conversion to degrees rotation should be easy enough, and simpler than trying to ensure that you are truly perpendicular to the piston? Am I missing something?

Online Triton Thrasher

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Re: Timing Tool
« Reply #12 on: 14.09. 2018 07:13 »
Why not just use a tdc finder and degree wheel? Using A10 stroke=84mm=3 5/16 inches=53/16 x 2 for a complete revolution, 3.4 degrees= 1/16".

That’s wrong.

Quote
Am I missing something?

How many inches piston travel is a crankshaft degree at TDC?

How many inches piston travel is a crankshaft degree when the piston is halfway down the bore?

Are those two the same number of inches?  No.

This might work. 

http://www.dansmc.com/mc_software2.htm

Offline Colsbeeza

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Re: Timing Tool
« Reply #13 on: 14.09. 2018 11:35 »
This is better

http://www.a7a10.net/forum/index.php?topic=195.0

Beezageek had it all worked out in 2007

Col
Colsbeeza
Australia

Offline jachenbach

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Re: Timing Tool
« Reply #14 on: 15.09. 2018 11:44 »
Hmmm. I see I way oversimplified. Accel/decel of piston depending on crank position easy to visualize. Struggling a bit to figure how rod length factors into this. Good brain exercise.