Carbie advice =Hard starting???

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Hi My 1970 commando 750 S is original with points and carbies.I will probably go electronic ignition but would like to keep the twin amals if possible. The bike is a bitch to start when cold. often to the point of giving up on the idea of a ride, however once hot it is a first kicker. There seems to be heaps of spark and it runs great ,doesnt kick back so timing isnt an issue either i dont think. Battery is fully charged . I,m sure its not an electrical issue as i can spray aerostart in the air cleaner to kick it over, or else petrol str8 done the plug holes .gives instant bang as well. . I have twin amals (340) written on the body. Pulled them apart after giving up trying to start and the slides appear to be dry , There was a bit of crap in the bowls and around the place so I cleaned everything and put back together but still no difference, , Not having had the bike long i dont know the quircks of getting it running i guess, My gut feeling is its not getting fuel. plugs seem dry also after trying to kick it for ten minutes i tickle it to the point of fuel spitting out and use no choke mostly to get it running. Thats the background now the questions. Is it possible to rejet to make it easier to start,I couldnt read the main jet size currently in them.( I only ride it occasionly and i dont need 10/10 power if its a trade off id prefer the easy starting). Does the needle setting influence starting? I havent checked which notch it is set to yet.Worst case would be to go to one carbie.Should i stay with one of the amals or put a mikuni on. As mentiioned id prefer to stay original but whats the point if i cant start it. I noticed the inlet manifolds are pitted and rough inside is that normal? i would assume smooth air flow would be better, if they should be smooth will it be best to polish them smooth or to replace with new. Any advice will be appreciated, Its New years eve here in Aus so wishing you all a happy new year
 

L.A.B.

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The main jet, needle jet, needle type or position should really have no affect on the starting mixture, and as you have said that "it runs great" when it has started, then changing anything there will be likely to mess that up.

If you press the ticklers then fuel should run out of the carbs in only a few seconds.
Fuel should be seen to *just* run from the carbs before you attempt to start up, and this should not result in the dry plugs you have mentioned after kicking it over for a while. If the bike doesn't start within a few kicks then you will probably need to use the ticklers again. My own Commando does appear to benefit from a 'priming kick' with the ignition off, and then a short re-application of the ticklers before attempting to start it.

Some people have a tendency to twist the throttle open hard when kick starting, try to avoid that if possible, and the chokes are not normally needed, and some owners prefer to remove the choke slide assemblies anyway.
Commandos do seem to need a fairly vigorous kick to start them from cold, especially if any oil has drained to the sump.

I would suggest that you clean out the pilot systems as that may help if you have not already done so?: http://www.jba.bc.ca/Bushmans%20Carb%20 ... html#PILOT

Also check that the float bowl joint surfaces are completely flat, and that the float bowl joints and gaskets are sealing properly so that no air can be drawn in through the joints.

There's no reason why you shouldn't smooth out the insides of the manifolds a bit if they have a rough finish, but try not to remove too much metal.
 
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While looking at the bowls, pay close attention to the pins that hold the floats. I've had good results very lightly crimping the bowl edges to hold the pins tightly in cases where the carb is slow to tickle. Some times the pins are a bit sloppy, and move around. Many years ago, I had a similar symptom while starting an A65. I was not getting a good tickle. Crimping the bowls was all it took. This is mentioned in the INOA tech digest.
 

Ron L

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Don't under estimate the advantage of the electronic ignition. Even though you have "good" spark, it must be delivered at the proper time. I have seen Boyer or RITA ignitions transform many hard starters to one kick.

Since you say you plan this change anyway, do it first and then see if you need further sorting of the fuel delivery system.

I have three Commando's on electronic ignitions, two Boyers and one RITA. Two have dual Amals and one dual Mikuni's. All are one to two kick starters.
 
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A one kicker when hot should be an easy cold starter, my 850 always starts first kick but only after a really good apllication of the tickle which results in petrol leaking generously from the carbs. If it stops after a few seconds it always needs a retickle before it restarts.
 
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mant thanks

thanks for the replies guys, especially lab , i revisted the cleaning of the jets (pilot) and with a bit of fine gauge wire maybe made a difference, put it back together and it actually started 3rd kick.
electronic ignition arrives tomorrow so i will fit that and who knows it may turn into a one kicker
 
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