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#663054 - 08/06/16 2:53 pm Am I being Stupid?  
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TJB Offline
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OK Guy's who can answer this?

1970 BSA B25/TR25W 250cc Engine. The Stats say that the Fully Advance timing position is 37 degrees BTDC.

Now can you explain this?

After finding TDC I place a mark on the Stator, I then place a fixed pointer opposite. I turn the Stator forward 37 degrees BTDC and place a mark on the Stator. I then rotate the engine a couple of times to confirm this is the correct position.

I'm using a MKIV Boyer set-up and set the pick-up magnets so that they are level through the Anticlockwise Timing hole (about 9 o'clock) at the Fully Advance position (37 degrees).

I start the engine (if I can) and attach a Strobe Light, the light shows that the stator mark is aligned with the pointer and when I rev the engine the mark moves away from the stator in a clockwise direction. (NB: Stator rotates anticlockwise)

Surely I need to set the Boyer up, so that it is in its fully retarded position (similar to the points system) and therefore when I rev it up the electronics advances it to the 37 degrees. Is this position 12 degrees, thus giving a retarded position of 25 degrees, or am I cracking up?

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#663056 - 08/06/16 3:09 pm Re: Am I being Stupid? [Re: TJB]  
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kommando Online content
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Why aren't you using the forward hole under the small inspection cover to set the 37 fully advanced, the flywheel hole the pin drops into at 37 fully advanced is very accurate so you end up with only one mark on your alternator stator not 2 which can be confusing. You do the initial timing on the Boyer at fully advanced at the box retards the timing at slower speeds not advancing at higher speeds (it works out the same'ish but the baselines are at opposite ends). Its normally out quite a few degrees so when you stobe at 5000rpm you always have to adjust it, normally retarding it, I have had them way out.

#663057 - 08/06/16 3:28 pm Re: Am I being Stupid? [Re: TJB]  
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Sounds like you have this set up right but I'm getting lost in why you placed a fixed pointer "opposite" (although 180 degrees won't change anything just why not put the pointer where the mark is?) and when you refer to 25 degrees being a "position"

This I'm know from my own 58 A10- 12 degrees BTDC is about where they idle, but that number is never as important at the advanced position at 3,000 plus RPMs or AKA "max advance". Advanced position max being about 37 degrees give you a idle at 12, and total advance of 25 degrees between the two.

Degree wheels can be amazing tools, SRM may make one for your model. Or be spot on when making your own marks, or even better some test lights have an advance knob on them. (all of this assumes you have your 0 mark spot on), run the bike at an RPM where the advance is max (3000/3500 plus?) while running the timing light turn the knob until the mark comes back to zero. Look at the knob and that number (37 etc) is your advanced. Kind of of nice cause it works when you have only a 0 mark to work with.

My real two cents is unless your racing this thing for prize money set the advanced to 35. You likely won't notice it and with the variety of fuel out there you lesson the chance of some pinging/knock on the engine.

Last edited by mikelucas; 08/06/16 3:29 pm.
#663058 - 08/06/16 3:32 pm Re: Am I being Stupid? [Re: kommando]  
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I have, I don't have the correct pin, but I checked my mark with the hole in the flywheel and they match.

But why when I attach the strobe it shows that the marks are aligned on tick over and move apart when you rev it up, if the Boyer unit adjust it?

#663059 - 08/06/16 3:43 pm Re: Am I being Stupid? [Re: mikelucas]  
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Mike, you lost me a bit with your text, unfortunately.

I have TDC, I have 37 degrees BTDC, which aligns with the flywheel mark. The 12 degrees I got from the old Advance & Retarded unit which has now been replaced by the Boyer.

I know from timing my C15 with pints in a distributor that you set it up with the weights in the fully advanced position and obviously when you start it, initially its in the retarded position.

So how come that my cheap non adjustable strobe light shows that its firing at 37 degrees BTDC on tick over?

#663065 - 08/06/16 4:06 pm Re: Am I being Stupid? [Re: TJB]  
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Allan Gill Offline
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Because you have done something wrong.

Use the correct markings on the case, and everything as per the manual. Forget trying to find TDC and working back. Just use the original markers.

Then set your Boyer so that the dot on the magnet is in the middle of the view hole. Start the bike up. It will be about 3-4 degrees advanced at full advance. Then adjust the timing until the pointer aligns with the rotor mark.

Simples. Forget the 12 degree advance on the points unit. Your not using that any more. The advance range on the Boyer will be different to the AAU that your used to, so just work with full advance only.

Moving on from that, I no longer strobe time any of my engines, I find the rough timing mark then tune by riding and testing, advancing or retarding until I find optimum running to suit my riding. Fixed advance will be optimum for what I require more advance in the midrange but less advanced at the top end which helps with higher rpm. But i divert from your question.


beerchug
#663076 - 08/06/16 6:35 pm Re: Am I being Stupid? [Re: Allan Gill]  
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In conjunction with the flywheel locator thing ,
The primary side cover , if original , should have a hole for timing ...
With timing marks like this

The pointer , located around 5 o'clock , is sometimes missing
or not noticed until some good light is shown on it .
.

#663117 - 08/07/16 5:24 am Re: Am I being Stupid? [Re: quinten]  
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Well chaps, I've checked and double checked ALL of the methods to confirm 37 degrees BTDC and the flywheel plug and my Timing card method agree and the pointer/primary cover is 1/8" different. The Boyer hole/magnet screw shows little or no difference.

The engine, when started sound and runs OK. I'm having trouble starting her, which I've put down to carburation. It will only start with a fixed throttle opening, if you open the throttle when kicking her over it kills the start.

I still can't explain why the strobe is showing the timing marks spot on at tick over.

#663118 - 08/07/16 5:27 am Re: Am I being Stupid? [Re: TJB]  
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Allan Gill Offline
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Originally Posted By TJB
Well chaps, I've checked and double checked ALL of the methods to confirm 37 degrees BTDC and the flywheel plug and my Timing card method agree and the pointer/primary cover is 1/8" different. The Boyer hole/magnet screw shows little or no difference.

The engine, when started sound and runs OK. I'm having trouble starting her, which I've put down to carburation. It will only start with a fixed throttle opening, if you open the throttle when kicking her over it kills the start.

I still can't explain why the strobe is showing the timing marks spot on at tick over.


Because it needs adjusting to suit the fully advanced position.

The reason it's struggling to start is likely to be fuel dried up and blocking the pilot circuit and the Welch plugs/transition ports.


beerchug
#663119 - 08/07/16 5:39 am Re: Am I being Stupid? [Re: TJB]  
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kommando Online content
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Quote:
I still can't explain why the strobe is showing the timing marks spot on at tick over.


From my first post

Quote:
Its normally out quite a few degrees so when you stobe at 5000rpm you always have to adjust it, normally retarding it, I have had them way out.


Its a starting point only when you line the magnet up under the hole, I changed boxes only and left the magnets and timing stator as is and had to advance 10 or 15 degrees immediately as the boxes react differently to the pulse from the magnets and I must have had 2 at the extremes.

#663122 - 08/07/16 5:47 am Re: Am I being Stupid? [Re: TJB]  
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In the first post do you mean Rotor when you write stator, the rotor rotates, the stator is stationary. This makes the first post hard to diagnose.


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#663135 - 08/07/16 7:19 am Re: Am I being Stupid? [Re: gavin eisler]  
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Sorry yes the rotor.

#663138 - 08/07/16 8:49 am Re: Am I being Stupid? [Re: kommando]  
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You say you are turning it forward 37deg,from tdc you should be turning itBACKWARDS 37 deg from TDC to get the before tdc.

#663142 - 08/07/16 9:56 am Re: Am I being Stupid? [Re: TJB]  
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my mistake again

#663144 - 08/07/16 10:36 am Re: Am I being Stupid? [Re: TJB]  
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I might of missed this but what RPM are you checking the timing at?

#663155 - 08/07/16 11:45 am Re: Am I being Stupid? [Re: TJB]  
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"After finding TDC I place a mark on the rotor, I then place a fixed pointer opposite. I turn the Rotor forward 37 degrees BTDC and place a mark on the rotor. I then rotate the engine a couple of times to confirm this is the correct position."
corrected for terminology. Still wrong though , the answer to your title question is yes!.

To get the BTDC figure you must rotate the motor, backwards , clockwise, 37 degrees, not forwards.
The spark comes before TDC, not after in the max advance position. Ideally you rotate back beyond 37 degrees then forward to the exact mark to take up backlash in the timing gears.

Last edited by gavin eisler; 08/07/16 2:59 pm.

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The poster formerly known as Pod
#663159 - 08/07/16 12:43 pm Re: Am I being Stupid? [Re: gavin eisler]  
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Yes its my terminology that is wrong. I should have said 'I turn the Rotor backwards (anticlockwise), not forwards.

#663170 - 08/07/16 3:02 pm Re: Am I being Stupid? [Re: TJB]  
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Sorry, i got my bit wrong, the motor should be turned back clockwise to the 37 BTDC viewed from drive side. I corrected the post above. If you turned it anti clock you went the wrong way.

Last edited by gavin eisler; 08/07/16 3:02 pm.

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The poster formerly known as Pod
#663215 - 08/07/16 8:30 pm Re: Am I being Stupid? [Re: TJB]  
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Peering through the mist of misinformation it sounds like you need to move the Boyer rotor magnet, if you dont have the range to adjust for correct timing with the slots in the timing plate.
What the others say about carbs and pilot jets is good info as well.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
#663232 - 08/08/16 1:30 am Re: Am I being Stupid? [Re: gavin eisler]  
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Originally Posted By gavin eisler
Peering through the mist of misinformation it sounds like you need to move the Boyer rotor magnet, if you dont have the range to adjust for correct timing with the slots in the timing plate.
What the others say about carbs and pilot jets is good info as well.



The Boyer rotor isn't a magnet, is it?


Amateur Loctite enthusiast.
#663244 - 08/08/16 4:54 am Re: Am I being Stupid? [Re: TJB]  
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The Boyer rotor has magnets on it, mine does .Given that forward is the new backward, opposite is the new adjacent, anti clock is clock and rotors are the new stators , maybe I should have been more missleading. This sort of thread makes me question the moon landings.

Last edited by gavin eisler; 08/08/16 5:03 am.

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#663256 - 08/08/16 7:31 am Re: Am I being Stupid? [Re: TJB]  
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rotor = rotates

Stator = stationary


beerchug
#663273 - 08/08/16 10:11 am Re: Am I being Stupid? [Re: gavin eisler]  
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Originally Posted By gavin eisler
This sort of thread makes me question the moon landings.


LOL

#663275 - 08/08/16 10:30 am Re: Am I being Stupid? [Re: gavin eisler]  
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Lannis Online content
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Originally Posted By gavin eisler
The boyer rotor has magnets on it, mine does .Given that forward is the new backward, opposite is the new adjacent, anti clock is clock and rotors are the new stators , maybe I should have been more missleading. This sort of thread makes me question the moon landings.


The guys who engineered the equipment and methods for the moon landings were educated in one-room schoolhouses with a wood stove (probably) and did their calculations with a slide rule.

We've gotten too smart to do that any more ....


OK, I admit it, I'm addicted to brake fluid.

But I can stop any time I want.
#663276 - 08/08/16 10:37 am Re: Am I being Stupid? [Re: TJB]  
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Some times just keeping to the standard factory ignition system is no bad thing, so easy to time with a strobe. Had a tuned B25 Starfire which revved to 9,000 and never had any problems and it was my road bike for two years.
Goldie John.

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