I have rebuilt a 1963 650SS with two new Amal Monobloc 376 carbs with no air slides fitted. However, I can't start it. It will fire occasionally and kick back but that's all. I will recheck the timing.
Were air slides/chokes fitted originally to twin carb models and will they help?
Hello i have same problem on my commando someone takes out slides from karbs. and in winter i can not start my bike. only way was take fuel under sparks. now i take back slides and machine takes on second kick in winter.
on 650 ss i have carbs with slides and starts good.
but timing can makes this problems too.
here is schema of carb with choke slides
Don't racers remove air slides because they are just one more thing to go wrong? And one more thing to maintain. They were certainly fitted originally so I wonder why you have left them off if the carbs are new. if you don't have them - have you blocked the cable entry holes at the tops of the carbs?
If it won't start - are you sure you have flooded the float chamber? All the books and magazines repeat the comment made by the road tester in 'Motorcycling' that the downdraft carbs are prone to flooding and this then makes starting a problem. I've never found that to be true myself. But I certainly use the air slides when it's cold, but only for a very short time.
When setting up a race bike, you remove all unnecessary parts to get it as light as possible. First you don't race in really cold weather. Second you warm up the engine before race to get oil flowing easily and to get correct carburation. If needed when cold you can get choking simply by partially masking air intake with your hand. The air slide on the GP carbs was mainly for fine tuning mixture depending on different air pressure and temperature. Most racers omitted them.
I do have them but was advised by someone that they weren't really necessary so I removed them and blocked the cable holes.
Yes, I have flooded the float chamber. I've also tried easy start spray to no avail.
hello this sounds like timing is out and may have been timed up wrongly to do the timing you should all ways start from the drive side or left side with the point turned up ward and the points cam at the bottom or coming too the bottom then you find were the breaking point is on the points and have the left hand piston at 32 degrees before top dead center with your ATD on full advance and points just breaking with your fag paper try to keep all this still and do up the ATD bolt and it would good if you can fit a pair of choke sides just to take up the space and stop too much air getting in the carbs making it run very weak, hope this may shed a light on things have fun yours anna j
I am fitting the choke slides and will redo the timing. I have manual advance/retard
Hello Normally The 650SS has Automatic Timing device, So what Magneto have you has all 650ss Had the Lucas Competition K2FC, Only the Delux 650 and Standard 650s Had the Coil-ignition The Norton Manxman 650 right from November 7th 1960 had the Lucas K2FC and their date stamped on each Magneto to the Motor, like my Norton Manxman 650 has the date stamp on the magneto 12/60 and with a manual advace and retard lever as to be fully advanced and all your timing is done from the left-hand side with a timing disc fixed well to the crank end three bit of glue tack at the back of the timing disc then fixed to the rotor and do up the big nut, hand tight and fix a good pointer on the rear barrel stud, and take thing from there have fun and good luck yours anna j
It's a K2F with a cutout button on the end. Based on the box of bits I bought it's probably not the original!
How is the starting now that you have replaced the slides?
I haven't had time to do anything yet as I'm away. I'll report progress when I can.
You need to make sure you have good sparks too, not just feeble ones. It should run without the choke slides but may of course need tickling a little while very cold. The mags can be rebuilt if required to restore the sparks.
I've had the mag serviced an it sparks ok.