Power arc guinnea pig.

UPS delivered the package. Looks to be a simple install. Need to get a few bits and pieces at the auto supply and will start on it tonight. Reading through the literature I noticed that Power Arc has a 6 month warranty, and Old Britts will extend it to 1 year! Awesome!

System is installed and wired. All that's left is to cut and install plug wires, find tdc to set timing disk and fire. Will install tympanum regulator after I know the ign is ok. Pretty easy. More room under the tank now the Boyer box is gone.

Glad to hear its going as advertised, so far. Lack of box under spine leaves freer routes for stuff. Will be grinning inside with ya awaiting the new noise.

And the winner is... wait for it...
Power arc by two lengths!!!
Had a bit of trouble with the timing disk thingie, but worked it out. Fired first kick, and is smooth through all rpm's. Being me I chose the more aggressive curve. Will install a switch sometime in the future though to select between the two. Will take it out for a few miles tonight after dinner.

Now that's news we can use. Remember you disc fiddle I may have to consult ya in a season or two. Ah the luxury to leave your cares behind with an after dinner lark. I'm afraid of the dark now, used to love it. There's an used switch on bar, forget how it works but maybe it could be adapted for curve selection. Wonder how much DIY advance/ retard can be detected.

Tries to throw you over the handle bars if you don't crack the throttle when you kick it. No pinging or detonating heard. Deffinately sounds better. Super throaty. Nice sound on deceleration. Might make some marks in case I want to fiddle with it. The disk thingie is a real pain to snug down, it wants to move with the bolt head. Gotta get a bit ahead of it and tighten up/ spin till the light comes on and hope that the locktight keeps it on mark. :?

Good mid to high. Thinking its a bit advanced. Gonna bump it back a degree or two.

Yah, definitely need to retard it a few degrees. Kicked and backfired when I tried to start it after sitting for a bit.

Rich and retarded. Like I like my women.

caddy chris said:

Yah, definitely need to retard it a few degrees. Kicked and backfired when I tried to start it after sitting for a bit.

Rich and retarded. Like I like my women.

Click to expand...

great sounds like it will be nice - how confident that you set it exactly like the instructions - reason asking - curious if the prescribed timing method is a little off (wouldn't be to surprising) or you were not quite at TDC and took a very close guess-ta-mate -
m

Yah, tdc found via stick-in-hole method. Not very accurate, but gets close enough to be able to run and dial in. So, if I remember correctly, the cam spins counter(anti) clockwise so ill move the disk thingie clockwise a tick and see how she goes. Not real technical, but it'll do.

"Not real technical, but it'll do."
So you have alot of interest in this, why not think that through? What are you going to move clockwise? If you move the thing that was once the point plate clockwise on a machine that has a C.C. cam you will advance the timing. When you volunteer to be an example for the rest of us on the forum you kind of got to be careful with the words. It’s just my opinion but with a dead stop tool it only takes 5 minutes to set up and get it all right. Than you could know that the gage in your primary is good or off a little. And all the rest of us could benefit from your trouble having a real bench mark for the new to us, system. Many of us would be able to help you get this right so that your numbers could be of good use. Using a strobe light in the primary gage and talking a little about how it behaves under that light when it’s revved would be even nicer.

Aw poo, its a freaking ancient Commando for gosh sakes, just fiddle with the initial timing so it don't back fire hardly at all on kicking and keep backing off till no detonation if any detected by the no back fire initial setting, then when most pleased with the performance = put a light on it to mark for future and tell us what ya found.

Powerac has 3 spark feature for faster burn, so I'd expect a bit more retard than prior ignitions will be found best for max pressure after TDC instead of working against earlier spark pressure before TDC.

Retarded spark setting can mean two things, one its too close to detonation explosion to start earlier, two the burn is so fast-thorough it don't need much a head start.

Careful what ya stick in plug hole for piston stop, piston ain't going up/dn in relation to plug hole bore, so as piston comes up it can break/bend the plug probe side ways. I know how to get the metal clad eraser end of pencils out now : (

Norbsa- I have read your tech about the tdc dead stop, and find it would be a very useful tool to have on the shelf, and will probably make one some day. If I wasn't clear enough about the operation of this system, I appologise. Let me try to clarify.

The breaker plate is replaced by a fixed pickup unit. A disk with 100 slots cut in it is bolted to the cam in place of the lobes that formorly worked the breaker points. The pickup has constantly emits an infrared beam that is sensed when one of the slots/windows passes by allowing the "eye" on the pickup to see the beam. 100 windows =3.6 degrees per window.

Being that the pickup ( former breaker plate ) is fixed, all timing adjustment is made by moving the disk. Cam rotation is ccw so moving the disk cw fires the spark later.

That said... I made some reference marks on the pickup body and the disk. I adjusted the disk one slot/window cw. This retarded the timing 3.6° from previous setpoint. The bike still wants to kick back on starting but performance is better throughout rpm range and engine runs very smooth cruising at any speeds.

Hobot- I was thinking the same thing. Contemplating hooking up switch to change mapping, if for nothing else but to use the milder map for starting...? Just thinking out loud.

As it may sound complicated to some, this is NOT rocket science! Way easier than adjusting and maintaining dual points. And once its done, its done.

AH yeah, switch retard for safe easy kicking, then switch advance for actual riding, because I too found knee locked backfire initial timing was best for riding, once got back off ground crying with new knee injury, 3 wks after avatar scattered R knee and had time switch points to Boyer. Squatting install was tricky.

Unused switch on mine is under the throttle hand, which I've got hand on to start anyway, so maybe can also hold start switch/retard on till fires then release as I do the slightly too open throttle on cold start up. I assume the optical disc is not limited to one notch only but infinite partial notch adjustment, if ya can stand the tedium with guessing the slip factor on nip up.

Would be neat to see the curves Fred developed.

Im not going to give timing degree settings because all our bikes are different and what works for mine might not work for someone else. Use the TDC light as a base and go from there. A liming light wont work to adjust timing while running because the disk is your adjustment point and its spinning when running, so I think the pencil lead referecnce point method is best for this system. Once I have it dialed i'll make sharpie or paint pen marks for future.

Hobot- im only using left hand switchgear for high/low beam selection and nothing else. Horn, blinkers and other non esential :mrgreen: accessories have been eliminated. Right hand switchgear is only there for front brake m/c. K.I.S.S.! May use blinker switch for map selection, but that would mean soldering new wires as I have clipped origionals.

Right now all I can say is that im approximately 4° retarded from MY initial setpoint which was determined using a soda straw (take note hobot!) to find tdc.

Iwill post more if I make any changes, and try to answer any questions anyone has.

oH my Chris I feel so naked vulnerable w/o a strong horn. Soft safe soda straw, smack!, duh next time your wisdom may save me another blank staring show stopper state. I've given up on anything but knife razor marks as fine enough, trouble is can't remove em when found to be not quite right : (

Loud pipes! Couple blips get attention. Sharpie works for me. Been doing it on my cars forever. Mark dizzy on shaft to the intake or block for reference for adjustment without timinfg light. If you need.to change it just wipe it off with a rag n carb cleaner and make new ones.

I read on here that bit, little bit and little little bit are technical measures in norton terminology.

Out riding and heard a noise haven't heard ol gurtrude make before... strange chirp noise from the rear tire at 6k 1st to 2nd gear shift! Hmmm. Is this normal...???!! Hahahahahahahahahah! :lol:

caddy chris said:

Out riding and heard a noise haven't heard ol gurtrude make before... strange chirp noise from the rear tire at 6k 1st to 2nd gear shift! Hmmm. Is this normal...???!! Hahahahahahahahahah! :lol:

Click to expand...

i'm sure you'll hear other noises too if you continue the 6k 1st to 2nd shift..... :shock:

Like the tinkle tinkle of gears exiting at the speed of sound and embedding themselves in the asphalt sound? I hate that!
Fortunately its not a habit.

I did get it into the 6k+ range in 4th for a bit shortly after. Probaby not good either.
Sure was fun tho!!! :mrgreen: