Non starter!

My 650 is also quite a reluctant starter if left unused for more than a month. It will fire for a couple of turns and then decides it needs another rest. There then follows a bit of a game with several rounds of me keeping the choke on full, flooding the carb and then kicking. Each time the engine will fire and run for a bit longer until it stays running and the choke can be taken off. From then on the engine will always start easily, every day until the next long period of storage. This has got to be a fuel issue and I suspect that Ethanol is behind it...........

I used to own a very reliable, easy starting Commando fitted with an SU conversion. Then fuel with Ethanol in it arrived and it wasn't too long before my fuel pipes and some of the SU internals failed. The bike beame a pig to start until I purchased a new Premier Concentric.

Though good voltage is seen at the battery terminals why not investigate at the points/coils end a little corrosion on a joint and the magic will disappear.   Boyer is susceptible to low voltage.

I take it...

compression is adequate, no stuck rings or rusty seats ?

no wet sump situation reducing the speed of turnover?

carb was drained over winter?

 Points are set correctly and no high resistance across the closed contacts.

 For spark checking (when the missis is not available) I use a 3" all metal bulldog clip; the clip on to the fins and plug between the two press levers at the back.  If yours is a painted barrel you will have to clip onto the head...   They hold quite firm allowing you to observe the spark .

 As a trials rider in the dim and distant left foot kicking was the norm but when my joints start to fail I reverted to it for the Nortons.  Bike on stand where fitted, steering lock full left and left hand on  throttle,  if you have got a long lever 850 maybe a bit of extra height under you to get up to the full  stroke. ...May help you later on 

 Good  luck

Jon

Assuming that the bike started/ran fine before the Winter, I suggest that the main issue here is time and storage conditions. If the garage is a bit damp then corrosion of electrical contacts/connections may suffer thus, as suggested, check the voltage reaching the Boyer box - bare in mind the current from the battery has to pass through numerous connections and the ignition and kill switches, also check the earth connection to the Boyer. If the voltage reaching the Boyer unit is low, the ignition timing will advance to the point of making starting very difficult - likely to kick back if it does fire! Ensure that the plug caps are clean and dry. Check the wire connections on the Boyer stator plate are good - these are notorious for failing - you'll need to remove it to examine the reverse side. Are plugs damp/wet after kicking? - if not it may be blocked carb jets, now common with the horrible petrol we have to use. If the carbs weren't drained prior to storage then this might be your problem. I always used to turn off the petrol taps about half a mile before the end of my rides such that as I pulled onto my driveway, the engine would die with empty carbs. If you can stretch to it, both the new Tri Spark and Pazon ignition systems have an anti-kickback feature for kick and electric starting - I can vouch that system on the Tri Spark works a treat.

Let us know how you get on.

 .... test that voltage at the user end Dave. If it produces any sort of controllable spark it must be working, but "garbage in garbage out".

  As I remember there are two 6 volt coils in series on the "Rubberbed",  that means you have twice as many connections to go high resistance on you.

  A test for the Boyer is to switch the ign on and off; whilst the plugs are earthed and  visible. A spark should emanate from one plug or the other.

 If you are UK based I have a spare Boyer box you can substitute to prove your current installation.   You can keep if it resolves your issue, if not, prove it and offer it to the next "Noc'er" who is stumped; that's how I got it! 

Cheers

Jon

I got an intermittent  missing spark on one side with a Boyer as the engine earth route was not good enough to carry the full current from 2 sparks, added a direct earth wire from head to battery +ve terminal and full spark resumed.

Bare in mind that the Boyer system works on the 'wasted-spark' principle whereby BOTH plugs fire together - the ignition coils are wired in series. If you get a spark from one plug but not the other it suggests an HT problem with coil, HT cable/connection, plug cap or actual spark plug itself. It's also worth checking the low voltage wiring to the coils etc. Just because you see a spark with plugs 'on test' doesn't necessarily mean they're firing in the cylinders under compression.

whip out a plug, heat it up with blow torch, bang it back in. this is always my first fail me never !

Sometimes spark plugs can spark outside the cylinder and then not when they are screwed into the head and under pressure.  Start from the plugs [using substitution if possible] and work your way back up the electrical circuit.  Swap things from one side to the other.  I wouldn't normally move, alter or examine my Boyer which has been on the machine for 38 years.  The carburettor may have issues relating to ethanol which can impede starting; in my case, there were brown deposits from fuel pipes blocking the jets.  The best option is to ride all year around, if you can.  Good luck!

...there John, should see the state of my fingerprints ;-)

Click on the person's name, and then on 'contact'.

Too late now!

Recognizing all the above posts my issue was tank lining breaking up over the winter and blockes carb on the Dommie. With my T120 R it was the Boyer which was very reliable for 15 years but then gave up but new Wassells system solved the problem. Trust helps Hugh  

...may well deliver.  At least we learn that if you click on the name you can contact each other directly, always was bemused by the mails I received from other members...

 Did  you try ign on ign off test with plugs out and earthed??  sparks  should  fly...

 Hope you haven't burnt NGK into your thumb yet!!!   John was right on with that tip, also   used to use a pencil on the electrode to get the sparks jumping on my Bantam trials bike in 68 

Cheers

Jon

Just packaging it up in sterile bubble wrap (though I cant  guarantee what inside the bubbles)  :-)

have a look at:-

https://www.nortonownersclub.org/html/archive/rh/290/rh290_files/assets/basic-html/page-19.html#

Just use your DVM in place of the LED mentioned.

Tony

Hi 

Just been briefly through the posts on this thread, taking it away from the ignition. 

After the lay up, you did drain the sump of the oil, probably the whole oil tank would be in there. I remember trying  to start a Commando after a long lay up, I was not aware of this at the time and the bike would fire but the amount of oil in the sump would not allow it to start.

Hi, Just seen this and I'm not sure if anyone has mentioned the carb. The Mikuni uses and enriching jet rather than a choke. The jet can become blocked and not function properly. The moment that happens, what makes Mikuni first time starters suddenly becomes a total pig. It's quite easy to take that jet apparatus out and blow it out with compressed air.

David:

Are you going to take the switch apart and clean the contacts or are you just going to buy a new switch?

If you are going to take it apart, let us know how it goes.

Mike