Just checking about the choke you didn't mention it

Theres also a screen/filter? in the carburator clean it too, its near where the fuelhose goes into the carb (nut M14) don't smoke a sigaret when taking it out......

Timing, timing and do the timing. Check the points weights aren't catching on a popped dust cover
Then check for induction leaks as that's another cause for hesitation.

Solex carbs being fixed jet tend to go on for donkeys years and require liittle maintenance so unless you've ruled out everything else id not open it or start poking about unless your sure about it


Make sure the choke is fully open with the knob pushed in and that it works
Make su re the pipe to the airfilter is a good fit and not split, air filter is clean and lid secure
The Co2/idle jet should be set correctly while the engine is properly warmed up
Make sure you set the idle speed at 900rpm or higher so the alternator has a chance of keeping up with the battery
Make sure the voltage regulator is working and the brushes in the alternator are good
Make sure the battery is in good order and not placing too much load on the alternator

A quick way of flushing the jets is to get the engine at fast idle place the palm of your hand over the top of the carb and release before it stalls - this drags petrol through all the drillings the wrong way and is quite good at cleaning water in the jets

Make sure you dont have that horrible leaky cotton braided fuel hose or worse the original factory stuff (you may have to drop the tank to replace the bit on top if the rest looks ropey)

Fit your muff or give it time to warm up before you drive off as cold and damp weather causes similar symptoms

only then would i have a look at the idle jet.

....only sayin' an all

Thanks for the replies folks, I'll investigate those at the weekend.

Timing was done at harrogate, so don't think that was the culprit but ill double check.

Would that have been in the repair garage at ICCCR?
I know they're posh in Harrogate, but did that run to breaking out the strobe...
ken

( p.s. Don't think it's on Sean's epistle, but is there a 'choke pull-off device' on the top of the carburettor and if there is, does it still work or is it just a source of an air leak?


Limiting travel of choke flap. by slcchassis, on Flickr )

p.p.s. Wonder if the carburettor has ever been rejetted? 'Blown induction' setups with the later 26/35 carburettor need a 110 primary petrol jet to replace the original 102.5.
If that hasn't been done, the time needed for the engine to run correctly in cold weather after starting will be excessive and the mixture will be lean overall, with a risk of overheating if driven hard. )

Lol, not in the garage, just sitting on my arse with a beer and a strobe gun that was in the back of the van. Also remembered another symptom that has eluded me - running on when ignition switched off. Not every time and anywhere from about 2-10 secs long.

'Running on' is usually a sign that an engine is running too hot, or that there are 'hot spots' in the combustion chamber.
The former could be a fuel mixture which is too lean (addressed by rejetting), the latter is often plugs with too hot a heat range ( go one or even two steps colder than original recommendation, so B7HS or B8HS instead of B6HS in NGK's range).

so were down to timing and/or mixture? (check there is not a lean burn due to induction leaks spray petrol round the base of the carb and round the base of the manifold to head joints) a hot running engine is likley to crack the the insulation block under the carb.

primary jet as well?

ha ha ha just seen in other thread that your in Denny!

if you get no joy Im only 30mins away in Roslin (Ikea Edinburgh!)

Oh, and just remembered yet another another symptom - there tends to be a misfire on particularly miserable mornings. Originally was just every now and again, but seems to be getting more frequent.

Apologies for the forgetfulness. not been driving it much recently so these are mostly coming from memory