Old Brits Power Arc Ignition issue

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zotz

zotz

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I just installed a power arc system, (ignition, coil, plugs, wires) and am having a bit of a problem getting it dialed in. I've emailed Old Brits but as they may take a few days to get back to me I thought I'd check and see if any one has had any installation issues. Basically in regard to setting the timing. I did use a dial gauge and set it as per instructions but I am not getting the bike (70-750) running as smoothly as it did with the analog Boyer. Particularly below 3000 rpm. It also doesn't start as well. I could get it to start a bit better when I set the encoder disc to 2 deg after TDC.
 
Sorry to hear of your troubles, my installation went smoothly enough and the bike started right up. Wish I could offer some tech help, but I'm sure Fred over at Oldbritts will get back with you .
 
I had no issues with installation, other than the module did not fit in the housing (I had to file it down to fit).
Did not use a dial gauge, just the light on the unit to set the timing disk position when right cylinder at TDC (using a dull pencil to feel it).
And a good ground is essential. Good battery helps too. :mrgreen:

I have since retarded it a few degrees for easier starting.
 
zotz,
I was instructed by Fred to keep the ignition switch off until I was on the top of the compression stroke with the kick-starter before switching on. He said that the crank has to go in one direction without backpressure reversal, which may bring it out of the count sequence. It’s a little different starting technique than the Boyer system that you are use to. The unit counts the slots regardless of which direction the engine rotates. Thus you must have a good boot to the kicker to ensure its going only in the correct count sequence. Insure you use the plugs and HT wires that came with the kit. Hope that makes sense. Cheers,
Thomas
CNN
 
CanukNortonNut said:
zotz,
I was instructed by Fred to keep the ignition switch off until I was on the top of the compression stroke with the kick-starter before switching on. He said that the crank has to go in one direction without backpressure reversal, which may bring it out of the count sequence. It’s a little different starting technique than the Boyer system that you are use to. The unit counts the slots regardless of which direction the engine rotates. Thus you must have a good boot to the kicker to ensure its going only in the correct count sequence. Insure you use the plugs and HT wires that came with the kit. Hope that makes sense. Cheers,
Thomas
CNN
Click to expand...

good point about start up technique Thomas - very important. Mine starts cold first kick with ignition ON, but that after two kicks with it OFF. Primes the cylinders with fuel.
 
The pencil and kick-start method is not very accurate.
I use a cheap dial gauge from Harbor Freight and stick the probe into the spark plug hole.
Then I remove the primary cover and turn the motor using a big wrench on the crankshaft nut.
Using the kicker to turn the engine just doesn't give you the precision you need to land on TDC.
With a wrench you can rotate the engine back and forth and really zero it in.
I suppose a pencil or dowel rod would work in a pinch.
 
mschmitz57 said:
The pencil and kick-start method is not very accurate.
I use a cheap dial gauge from Harbor Freight and stick the probe into the spark plug hole.
Then I remove the timing cover and turn the motor using a big wrench on the crankshaft nut.
Using the kicker to turn the engine just doesn't give you the precision you need to land on TDC.
Click to expand...

I agree..I used a dial indicator after trying an old spoke thru the plug hole. I'm thinking there is at least 2 or 3 degrees of rotation either way that you miss by not using the indicator.
FWIW-my Power Arc works fine as long as you follow the advice above about having it up on compression and not letting it rotate backwards when the key is switched on. If it does kick back, turn the key off and rotate it through before retrying or it will continue to kick back.
 
mschmitz57 said:
The pencil and kick-start method is not very accurate.

I suppose a pencil or dowel rod would work in a pinch.
Click to expand...

I bet the pencil method is more accurate than what they used at the factory for initial settings. :roll:
When it comes to old British iron, precision is overrated. I prefer 'feel'.

but we digress...
 
Nah, setting the static timing is a cinch at the factory because they did it before the head is installed and the motor is sitting on a bench
(and a can of bleeding Watney's Red Barrel).

Probably just used a degree wheel or a calibrated piston stop tool thingy.
 
Unless you use a piston stop with the degree wheel, it's no more accurate than eye-balling, which isn't particularly accurate - though accurate enough for general operation. It would be very unlikely to get closer than 3-4 degrees, if that close, without a piston stop. That may account for the reports of factory timing mark inaccuracy though the one on my Norton was within 1/2 degree.
 
I alert ya that a pencil is too brittle a probe to use w/o great risk of snapping it off as piston does not rise directly in line with the plug angle so hit probe more sideways. At least pencil/wood floats to top in diesel to pick out through hole. Vendors sell a screw in probe with sliding center which don't slide on the piston angle contact either as designed. Primary cover off for a crank end marker/stopper is most sure method or put air in a jug and diddle crank till it stays up on its own.
 
Try it on a mag bike sometime.
Hours of fun.

Old Brits Power Arc Ignition issue
 
mschmitz57 said:
Try it on a mag bike sometime.
Hours of fun.

Old Brits Power Arc Ignition issue
Click to expand...
Been down that road too often for my liking on my BSA A10. Finally converted it to manual advance mag so I just have to be somewhere in the vicinity of 38/40 BTDC full advance and can dial it in by ear under way.
 
Mike G that is old school down and dirty method almost universally frowned on by best advice on this forum. I'd used solid stop with head off to index TDC in Trixie for points and a Pazion but when did a blow down test found one degree off from TDC till held crank stable against the piston force. That is why when I put time light on to see where best timing landed on the Combat it showed 29' instead of 28' total adv.
 
I just got back from a 1\2 hr ride. The bike started OK but I was not happy with how it ran. I got slight pre ignition when pulling away and the bike generally had a raw rough feel to it. Makes me feel it's too advanced but I did use a dial gauge and purposely retarded it 2 deg from the TDC recommendation. I got a reply from Fred at old Brits and said Issues are usually carbueration related but I ran a Boyer for years with no issues. He also mentioned to check wiring connections and proper seating of plug leads so I need to go over these when I get a chance. He also mentioned that you should not have to retard the unit at all.
 
I've got an old spark plug with the electrode pulled out and use a bubble of detergent to find TDC. After I've set the ignition timing, I check it with a strobe light and degree disc. If it isn't correct, the symptoms are similar to incorrect mixture. So it is essential to set the ignition timing to a fixed value or curve before you start re-jetting the carburettors.
 
zotz said:
I just got back from a 1\2 hr ride. The bike started OK but I was not happy with how it ran. I got slight pre ignition when pulling away and the bike generally had a raw rough feel to it. Makes me feel it's too advanced but I did use a dial gauge and purposely retarded it 2 deg from the TDC recommendation. I got a reply from Fred at old Brits and said Issues are usually carbueration related but I ran a Boyer for years with no issues. He also mentioned to check wiring connections and proper seating of plug leads so I need to go over these when I get a chance. He also mentioned that you should not have to retard the unit at all.
Click to expand...

Of course the problems are carburation related. If you change the ignition timing the carburation usually also needs to be changed, then you are fixing an error with an error and the bike goes backwards. Fit a degree wheel to it and get it right.
 
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