Looking for some input from the forum. I'm recently having starting troubles, even though to my knowledge nothing has changed. I'm very familiar with the standard starting procedure, and used it reliably and successfully for years (tickle the primer, retard timing a bit, choke, compression with bit of throttle, compression release with slight additional turnover, FIRM kick, go!). It used to start by the second kick, summer through winter.

I dismantled the carb and made sure all jets (including pilot) and air passages are clear. Checked the spark. I can start the bike with a spray of starter fluid. And once started, the bike idles and drives perfectly... so it doesn't seem to be a timing issue or petrol quality issue. My gut tells me it's just being flooded or too lean at starting, but this has never happened before. And I've now tried probably 100 variations on the starting procedure with zero success.

Any chance bad petrol would make for a rough start, even though it idles and runs well? I'm stumped.

Craig

I'm in the US and the starting procedure changed for my M20 and BSA C12 in the last year or so. I do not have any evidence, but I think the fuel is different, requiring a different technique. I used to flood both carbs and go through the basic routine you described (without the choke as I live in Florida), but now they start reliably with just a short time holding down the tickler, not flooding the carb.

Petrol,
You got a secret stash some where ?
Haven't been able to get petrol for years.
All that is available is fuel which seems to be a mixture of every toxic petrochemical solvent we are no longer allowed to use in light oil.
And yes there is about 5% wt/vol of highly volatiles ( usually called aromatics ) to enable the engine to start from cold.
there will quickly evaporate out of your tank yielding a mix that will not burn at lower temperatures.
Two important thigs to do when burning "fuel "

1) at the end of the day or any other time the engine will be started from stone cold run the carby dry.
The few seconds of lean( very hot ) burn as the last dregs run through the carb will stop the oily no burning crud from depositing on your plugs.

2) any time the bike is going to stand for 1 month or more, drain the tank almost dry, leaving just enough to keep the corks in the fuel taps from dring out then refill with nice new fresh fuel before you try & start it next time

email (option): wariron@tpg,com,au

When you have gone through you usual procedure , this is what my granddad showed me and he worked at the Bsa in the late 30's 40's and 50's ect put her on full advance then retard her slightly prime carb till petrol spat out valve lifter in then kick over three time to wet the piston chock full on get her just over TDC and a good firm swinging kick , and this is what iv done for the last 25 years or so ! never failed me
Gary

email (option): garypitt@talktalk.net

I would check the condition of the points. I have found a bike will run on points worn and burnt, but starting becomes harder.

Thanks for the tips all. I'll keep experimenting and see what the main culprit is!

Hi Craig,
let us know how you get on.

Are you sure your ignition is Ok ?
And the spark plug, HT lead, brushes etc ?