Rebuild 1st startup issue

Just finished (another) full engine rebuild on MkIII 850. Prior rebuild in '07 included 10:1cr, +.040 pistons, Johnson J380 cam (replacing Axtel S3), and legacy 32mm sleeved Amals and Boyer. Engine was very strong and always 1-2 kick starter since purchase in 1977. First rebuild was in 1980 to Clymer manual "Stage 1".

Cause was detonation failure on right side in '14 due to sleeved Amal coming apart when running bike hard. Sent head and cylinder out for rework & re-bore (+.060) and purchased Power Arc ignition (full kit w/ coil, plugs, etc) from Old Britts and PWK 34mm carbs from Jim S in '14. Business commitments delayed reassembly until now.

Review of cam found a couple of lobes scarred. Johnson Cams reworked cam and faced followers. Send AP to Fred at Old Britts. He tested, updated firmware and 2 tunes in PA ignition.

Bike will not start (kick, no ES) after several days of attempts. Occasional pop and (sometimes vicious) kickback. Fred Eaton and Jim Schmidt have been very helpful and we have conducted several tests, but things basically remain at square one. Hopeful somebody here has ideas. Here are the vitals and attempted fixes:

• Ignition (and other) electrical circuits run through solenoids to avoid voltage drop/failure through old switches ('07). Set at measured TDC per AP instructions. NGK Tried to start on both curves. No difference.
• Wired PA direct to (new) battery per Fred. Placed plugs on cyl head and kicked over. Both plugs were firing simultaneously (not under compression however). Tried to start this way. No Joy. Re-connected to solenoid setup. Same visual firing and No Joy when installed.
• PWK 34mm carbs purchased with full kit with fuel lines/filter. Jets include [HASHTAG]#150[/HASHTAG] mains, #38 idle jets, [HASHTAG]#102[/HASHTAG] needles second notch down. Disassembled and blown out all orifices. Set up/synch'd per Jim's instructions.
• Tried priming cylinders with a tsp of gas ea (per Jim) and kick over. no Joy.
• Performed simple cylinder leakage test. Rings obviously not bedded in. No leakage evident/heard at intake or exhaust even at elevated pressures.

I have checked every adjustment/connection I could think of several times. I must be missing something. Unfortunately the Amals and Boyer are gone. Otherwise I would change one to prior known working status.

No slight to Jim or Fred. They have both been super helpful. As was Harold at Johnson Cam.

Thanks.
Dave Winship

Your experience brings back some really bad memories of a very similar experience I has a few years back. I had recently purchased my running, but recent years neglected Commando and decided it needed carbs and ignition updated. It had worn Amals and old Boyer. So I purchased PWKs from Jim and a PowerArk from Fred.
Installed according to instructions with help from a very knowledgeable Commando owner and friend. Many weeks of frustration and long sessions of 20-40 kicking marathons, only to have it finally start but run like crap.
Now running beautifully with new Amal Premiers and Trispark. Starts first or second kick warm or cold.
PM if you want more details, but suggest you try Amals or Mikuni, and Trispark or Pazon if you want to make progress.

PowerArc was problematic in my Commando. Changed it for a Trispark. Now a 1-2 kick start bike. Trispark not without issues. I've had a couple fail. Good customer service though.

Dave, check your Private Messages, I sent you one.
And yes, I am the guy that tompro above mentioned as having helped him.

Hmm have you tried a new new battery ? sounds like a voltage drop is causing havoc .. what about the charging ciruit ? Do you have Zenner diode and the blue cap ? could be there is a fault elsewhere on ign circuit .. ie brake lights

It does say on their website that ht leads should not have less than 800 ohm per foot Are you using your previous l

Not trying to hijack this thread, but what exactly does go bad on the PowerArcs? I've had one in my 71 Commando for 5 years or so and have had no issues other than occasional kickback when starting. When that happens just turn the key off, kick slowly through one time and turn the key back on and no troubles. Unless the bike has sat for months at a time its a 1 or 2 kick process.

$130 or so gets you a new Boyer. Are you still using the old rectifier? If so, the new type is considered more reliable, I reckon.
And a good battery, as mentioned above, is a must.
Why do you have to kick it?

Mr. Rick said:

$130 or so gets you a new Boyer. Are you still using the old rectifier? If so, the new type is considered more reliable, I reckon.
And a good battery, as mentioned above, is a must.
Why do you have to kick it?

Click to expand...

Alternator is 180w 3 phase Sparx. Battery is brand new, full charge. Stock starter pawl stuck within 6 months of ownership in 1977. spun up the rotor so fast that wires were thrown outward with centrifugal force. Owned the bike for 40 years. Always started with 1-2 kicks. Didn't see the need or weight. Boyer is an option. I liked the rev limiter protection on PA. Always had good success with Old Britts.

oldmikew said:

Hmm have you tried a new new battery ? sounds like a voltage drop is causing havoc .. what about the charging ciruit ? Do you have Zenner diode and the blue cap ? could be there is a fault elsewhere on ign circuit .. ie brake lights

It does say on their website that ht leads should not have less than 800 ohm per foot Are you using your previous l

Click to expand...

180W 3 phase Sparx alt. No zenner diodes.
Pulled capacitor years ago. Might be worth connecting for test. Thanks.
No voltage drop. As stated, ignition is on separate circuit controlled by solenoid (so are HL hi/Lo, & horn). Wiring through ign switch/cutoff only power solenoid, power to ign goes direct from battery/alt. Connected directly to battery (only load) to test at Fred's request. No change. HT leads, coil and spark plugs were purchased from PA through OB with PA ignition. Dave

Dave I worked for some years at a bike breakers.. everything was run up before dismantling there was one of those grey imports ie home market Japanese bikes that we could not get to go.. it defeated not only us but our many helpful trade contacts. Throughly pissed off someone said lets just put the fxxxxx thingnback together with a new battery . There was absolutely nothing wrong with the battery on it , nevertheless , we did and it went ... why I do not know ... And this trick of the new battery was repeated with this particular model by a number of other London dealers
Perhaps there is a capacitance in batteries that certain ignitions sometimes need .. If it was mine I would hook up another battery just to see. What a drag for you..

The problem with having very smart people help you is that they miss the stupid answers and the stupid ideas... Luckily, I can help you with those.

I've never set up a powerarc ignition,... BUT I know that people setting up other ignitions have mis-identified the timing mark on the rotor for one of the raised edges of the pad that the rotor's timing mark is scribed onto... check that you're using the correct rotor mark. Verify that mark is correct so you know your initial ignition timing set up is close to it's best location.

However you are starting the bike, be it with the slides down and some sort of choke on, try this... Turn the choke lever off and raise the slides with the throttle control to 3/4 throttle and try kicking it. If it roars to life, your issue is carburation. (even if it won't stay running)

Get a squirt bottle with a straw like this (pictured below) fill it with fuel, pick up the slides, give a squirt down the throat of each open carb, then kick it over. Did it pop or want to start?? If it didn't even cough, your problem is ignition... *(which could be spark quality or spark timing)

Make sure your plug gaps are set tight. .025" maximum. The power arc does not create enough voltage for wider gaps. The higher the compression, the tighter the gap must be.

It takes a hard kick to start with a power arc. It will not create a spark on the first compression stroke so the engine must be turning fast enough on the second compression stroke to start -or you will just get a kickback.

comnoz said:

Make sure your plug gaps are set tight. .025" maximum. The power arc does not create enough voltage for wider gaps. The higher the compression, the tighter the gap must be.

It takes a hard kick to start with a power arc. It will not create a spark on the first compression stroke so the engine must be turning fast enough on the second compression stroke to start -or you will just get a kickback.

Click to expand...

Interesting. Since piston/rings assembled and installed dry (or my aging 170# body) I may not be getting enough spin. Will reduce plug gap (started at .032, reduced to .028, will go to <.025).

I realize that this may create a maelstrom but... are these optical p/u units that much better than older Boyer type magnetic p/u units? Not trying to start a magneto thread...

Dave

Are you confident that your ground loop is complete? That your connections are free of corrosion, and are tight?

o0norton0o said:

The problem with having very smart people help you is that they miss the stupid answers and the stupid ideas... Luckily, I can help you with those.

I've never set up a powerarc ignition,... BUT I know that people setting up other ignitions have mis-identified the timing mark on the rotor for one of the raised edges of the pad that the rotor's timing mark is scribed onto... check that you're using the correct rotor mark. Verify that mark is correct so you know your initial ignition timing set up is close to it's best location.

However you are starting the bike, be it with the slides down and some sort of choke on, try this... Turn the choke lever off and raise the slides with the throttle control to 3/4 throttle and try kicking it. If it roars to life, your issue is carburation. (even if it won't stay running)

Get a squirt bottle with a straw like this (pictured below) fill it with fuel, pick up the slides, give a squirt down the throat of each open carb, then kick it over. Did it pop or want to start?? If it didn't even cough, your problem is ignition... *(which could be spark quality or spark timing)

Click to expand...

RoadScholar said:

Are you confident that your ground loop is complete? That your connections are free of corrosion, and are tight?

Click to expand...

Good question. Everybody looks at the “hot” connections. Ground equally important. Bike is very sanitary and ground connections tight and uncontaminated. Gas spritzer is good idea. Tried pooping tbs gas into plug holes, sealed up and tried to start. No joy. D

Errr... that was “popping” not pooping... guy needs a little self respect.

So many suggestions from people with no experience using these products. Suggest you consider those that do.
And ask yourself why JSM no longer sells PWK carbs (aka Crapsides). Jim makes & sells some xcelent Norton stuff and I would not hesitate to purchase any now listed oon his site based on his reputation and expertise. But PWK carbs were a mistake. Support nightmare for him, many customers with bad results trying to overcome their poor tolerance manufacturing defects.
Fred also upstanding vendor and I bought many other good products from him. Another issue with PowerArc design not mentioned above by JC is counter wheel getting out of synch with Cam when kicking. That's why have to "reset" by cycling power.
My dos pesos...

austinnorton said:

I realize that this may create a maelstrom but... are these optical p/u units that much better than older Boyer type magnetic p/u units? Not trying to start a magneto thread...

Dave

Click to expand...

That has not been my experience. Jim

Power Arcs counts slots. There are 90 slots on a disk @ 4 degrees apart each slot that passes the P/A reader it then counts. (Either forward motion or backward on the cam) it adds + 4 degree count. As Jim Comstock stated above the P/A needs to move in one direction to get it to count for timing the fire stroke with a heavy first kick. If the engine did not start on the first kick stroke and moved slightly backward from coming against compression it may count slots in the wrong direction throwing the timing off. Turning the ignition key off then on again once you get the kicker back to compression resets the count. And as tomspro stated that’s why you have to “reset” It is not like a Boyer with a magnet that passes a coil 180 degrees apart. You are dealing with 4 degree increments that may or maybe many degrees out.
Cheers,

Thomas

Would imagine there are no convenient hills round Austin for a bump start. .. If you have got dry fitted rings then the cranking speed with conventional K/s will be low. RGM do an extended T160 style which is excellent but whether it would give sufficien extra whoomph ? Couldnt you get some mates to give you a good push ? Once its run it will ease up .

CanukNortonNut said:

Power Arcs counts slots. There are 90 slots on a disk @ 4 degrees apart each slot that passes the P/A reader it then counts. (Either forward motion or backward on the cam) it adds + 4 degree count. As Jim Comstock stated above the P/A needs to move in one direction to get it to count for timing the fire stroke with a heavy first kick. If the engine did not start on the first kick stroke and moved slightly backward from coming against compression it may count slots in the wrong direction throwing the timing off. Turning the ignition key off then on again once you get the kicker back to compression resets the count. And as tomspro stated that’s why you have to “reset” It is not like a Boyer with a magnet that passes a coil 180 degrees apart. You are dealing with 4 degree increments that may or maybe many degrees out.
Cheers,

Thomas

Click to expand...

Thanks. Understand PA position tracking mechanism & Boyer operation. Frankly, I am leaning towards replacing and going back to a magnetic p/u like Boyer. The newer "tri-spark" type optical p/u electronic units really seemed like a move forward. I especially liked the rev limit feature. However, I am becoming convinced (partially by Jim C's comment) that the theoretical improvements are not worth these kind of issues and that the best solution is to get another Boyer. The old one worked for years without problem so long as the battery did not go flat (fixed with 3 ph alt). I accept SOME tweaking with complex analog devices like carbs that deal with variable inputs. I am less forgiving about digital electronic devices like this (I do not accept tweaking my computer or phone CPU these days (accepting v occasional restarts, before anybody pipes up)), especially when it is installed into a freshly rebuilt system. The PWK carbs may be another issue. My original intent in 2014 was to install carbs first due to Amal sleeve failure. Detonation damage and time led to this juncture with multiple variables.

To Oldmike, yes I have a suitable hill near the house. Considered it, but my 69 yr old body didn't like the idea of pushing it back up the hill if it didn't work.