Not a good shakedown...

When was the last time the needle jet & needle were changed?

If they are worn out the engine will likely not even make 900f EGT and of course the plugs will never stay clean.
You should almost NEVER have to change a plug in a decent running commando.
If you do then your bike needs serious work.....

New jets, new needles...

As DaveM points out I do need to check the spark. I was ensuring the battery was fully topped off before checking that and just doing a visual inspection in the meantime to ensure nothing out of the ordinary. Will check the spark with my spare plug tonight.

Will look into all the electric connections and see where we're at! Also replacing the plugs, Iridium NGKs are going for $7.40 on Amazon. Am I correct in thinking BPR7EIX are what I need?

Thanks for all the advice. Paul did a great job on the build, no doubt something I've fiddled with or something's vibrated loose along the way...

Cheers,

- HJ

Joe, Sometimes the disc that holds the magnets for the electronic ignition on the end of the camshaft can slip on the taper and go out of time, so it is worth checking the ignition timing again once you are certain that you have a spark.

Joe,
Don't use these BPR7EIX with supressed caps, the R is for resistance.
Cash

HJ,

The BPR7EIX NGKs are what I'm using now in all of my British iron; a bit too cool for the TR3, but just right for the Victor and Mk3 in our temperate (PNW residents will appreciate the irony in that adjective) climate here in Seattle. Be sure that you use non-resistive caps and wires with these plugs.

Rick

Hungry J0e said:

New jets, new needles... HJ

Click to expand...

Are the needles matched to the spray tubes?

They are marked with little grooves above the circlip grooves.
3 grooves for a straight spray tube, 4 grooves for a cut away spray tube.
Mark 3's generally have a cut away spray tube.

MichaelB said:

Hungry J0e said:

New jets, new needles... HJ

Click to expand...

Are the needles matched to the spray tubes?

They are marked with little grooves above the circlip grooves.
3 grooves for a straight spray tube, 4 grooves for a cut away spray tube.
Mark 3's generally have a cut away spray tube.

Click to expand...

Hmm... I've never taken notice or knew there were two types of spray tubes. The Amals that came with the bike were in bad shape so these are not original. Thanks for the info, will add to list of things to look out for.

cash said:

Joe,
Don't use these BPR7EIX with supressed caps, the R is for resistance.
Cash

Click to expand...

Yup... already using BPR7ES, so no suppressed caps/resistor wires.

Cheers,

- HJ

Miss matched Amal parts will definitely give grief.
My memory has faded regarding the straight spray tube.
I know for sure it's 4 rings on the cutaway tube, the straight is either 3 or maybe 2 rings.
Someone will need to clarify.

Ok...

Replaced the plugs and cleaned all the electrical connections at the ignition box/condensors.

Got a good strong spark on both sides.

Tore into carbs, look good no issues. FWIW spray tubes are not cutaway and needles appear correct (two rings at the top). These are replacement Amals, the originals were in a sorry state and Paul replaced.

While the tank was off inspected valve clearances. Left exhaust was too tight (which may explain my oil on that side?), all others spot on.

Tried to start and again bad kickback.

Measured voltage at the ignition box (white wire leading to Sparx ignition box) with the ignition on. Measures 12.25V which should be plenty. Both coils read good resistance (2.5 ohms I think). Cleaned ground connection to head. Grounds to frame all look good.

Inspected all the electrical connections and cleaned any that look a little corroded. The red ground to the rectifier was almost totally pulled loose from the spade connector. Came free with little tug, I'll repair that this weekend. I don't think that should affect the ignition though on startup, as I thought the rectifier only served to provide proper voltage/charge to battery when the bike was running.

Where to go from here? Adjust timing?

Cheers,

- HJ

Disconnect condensors as excess baggage in electro ignitions and keep hunting bad connections-conductors. Too advanced first reports itself as back fire starts, which poor voltage flow can do to electro ignitions.

hobot said:

Disconnect condensors as excess baggage in electro ignitions and keep hunting bad connections-conductors. Too advanced first reports itself as back fire starts, which poor voltage flow can do to electro ignitions.

Click to expand...

Should read coils not condensors... corrected my post...

To clarify: No condensors on bike

Regarding voltage flow: I measure 12.25 V directly at supply to ignition box... so the box is getting good voltage. Checked and cleaned all the connections... read proper resistance across coils to ground... etc.

At this point might be time to open a book of spells and banish the demons. ugh.

Getting everything back together and going to check the timing. Purchased a cheap strobe at the local auto parts shop.

1. The Sparx unit instructions say to set the static timing at BTDC, but I see no reference on how to position BTDC in my Haynes or Clymer manuals. Do I goto TDC and back off until I see valve movement?

2. Corrected the loose ground going to the rectifier. The wires from the alternator coming through the back of the primary were very loose in their bullet connectors, coming free with minimal tugging. Expanded the bullet ends a bit to keep them in there firm, but when I went to reconnect them I had a surprise. The female ends coming from the alternator are both GY, but the male ends going to the rectifier are GY and WG. I took a guess as to how it was hooked up before, but will there be a serious consequence (i.e. fried electrics) if I got this backwards?

Any help would be most appreciated. Never attempted to set timing before so here goes...

Cheers,

- HJ

Loose alternator wires coming loose during a ride to gradually lower voltage to electronic ignition can suddenly make it sound and act like its about to blow up while blasting glowing embers of carbon and rust on following rider who will also think you've just blown up too...

All wires coming from alternator go to any-all the input wires to rectifier/regulator.
Yellow is the solid color on Podtronics rec/reg, same with Tympanium, iirc.
Single phase altn. has two wires out while 3 phase altn. has 3 out put wires.
It makes no difference which Altn. out put wires go to which factory rec/reg input wires. It just matters that rec/reg output ground and power leads go to correct +earth and -power connections to rest of bike. Its very frustrating to find as wires at rest look connected and conduct fine, till the vibes riding. A run up in the dark can sometimes reveal this and other leaks unknown.

I and my ride mate had so much trouble with worn out factory connections and wimpy flat blade replacement connections we gave up on them. My buddy twists and tapes together while I use wire nuts. One reason being they must come apart too often to service something the primary must come off. I hide the house wire nuts inside a cute plastic T-Rex dino egg-toy for extra head scratching on close looks. I'd solder the boogers but for need to un-do and lost of wire length each time, ugh. On my special I think I'll just twist em together good and shrink wrap to secure, then slice wrap and untwist and re-do as needed, long term.

If head light brightens on blip ups - pretty much proves ya got it working, till someday it don't again.

Looking at the wiring diagram I figured as much, but wanted to be sure!

Any advice on setting BTDC?

Cheers,

- HJ

First off its risky to stick stuff in plug hole to measure piston rise as the pistons come up more sideways to a probe and can break it off or bend it.

Best way is put a degree wheel on crank end, a strong magnet with spacers behind so wheel clears stuff. Then ya put a stopper in plug hole or on crank and turn crank full one way and mark degree, then full the other way and mark degree, then split difference for TDC and move degree wheel so it's 0-zero'd @ TDC. Then back up engine 30's or what ever your full advance is and mark alternator stator by knife score or make note/mark off where that lands on factory cover dial, ignoring its degree numbers till ya know if they are correct or not by above procedure. I also mark alternator for TDC and correct rotor slash so never need degree wheel again.

Time light bounces so much its an option call to judge middle of its moving blurring marks. I've gotten Ms Peel to show pretty dang steady time marks but she's special and had all new components. Trixie with used cam and points mech adv. is so blurry I just get close enough to start and then diddle by sound/feel/response, till back fires on kicking then retard till just don't, then mark timing plate position w/o regard to any stinking timing wheel or degree numbers to confuse the un-wary.

I'll have to admit too, with the points it does wander around a bit on the degree marking with the strobe. But it seems to run fine.

Dave
69S

Paul was right (as usual).

After firming up the bullet connectors from the alternator, bike started up next kick.

So loose electrical from the alternator appears to have been the gremlin.

Cheers,

- HJ