1971 750 Commandodo not start
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Peter R
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Piero, you say that you fitted reconditioned carburators, what else did you change or replace after your bike was running for the last time ? Are you sure that there is no blockage at the idle jets ? this is often not easy to see. Are you sure the carbs were rebuilt correctly ?
What is the battery voltage with the ignition switch on ?
What is the battery voltage with the ignition switch on ?
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way back in the good old days when my 750 was sitting in the garage rusting away, I used to start it once a year [ or try to ], and naturally the battery was stuffed. It never started easily and one day while giving an almighty kick, the starter pawl broke. Needless to say I was in total agony with the bike lying on top of me. I was lucky a neighbour saw it happen and came to my rescue. The bike always went well when it did start. It still has points ignition. That's also another reason why I always start these things on the main stand.DogT said:
Pierodn, you seem to have a good battery. Put another 2 new plugs in the bike. you never know, they my be dud, but not likely.
Take the air filter off and squirt petrol down the carbs with an oil can [1 squirt and throttle wide open of course ]. The thing has to fire if all else is well.
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Piero,
If fuel is getting through the spark plugs should be wet and smelling of petrol.
If this is not the case the carburettors still need to be examined (swap for a pair that are known to be good off another bike is best!)
If there is a spark, is it confirmed that the timing is right?
Sometimes the timing marks on the rotor can be wrong (off a different bike, perhaps?)
Check the marks are right by setting the piston at top dead centre, then check the timing mark on the rotor is correct.
Then re-check the timing.
Even if the timing is way off, I would expect some kind of response (i.e. broken foot/ankle...) :roll:
Something fundamental is clearly way off if you're getting no response at all. Is it possible the cam timing may be out?
If fuel is getting through the spark plugs should be wet and smelling of petrol.
If this is not the case the carburettors still need to be examined (swap for a pair that are known to be good off another bike is best!)
If there is a spark, is it confirmed that the timing is right?
Sometimes the timing marks on the rotor can be wrong (off a different bike, perhaps?)
Check the marks are right by setting the piston at top dead centre, then check the timing mark on the rotor is correct.
Then re-check the timing.
Even if the timing is way off, I would expect some kind of response (i.e. broken foot/ankle...) :roll:
Something fundamental is clearly way off if you're getting no response at all. Is it possible the cam timing may be out?
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pierodn, if you are confident that you are getting a rich fuel mixture which is required for a cold engine to start, then I would start looking elsewhere.
When I rebuilt my Norton 9 years ago, it would "pop" and "bang" when trying to start it but would not fire. There was a spark at the plug, and because I had a non standard carburettor on, I blamed the carburettor and so bought new Amal carburretors with the result........THE SAME!
The problem turned out to be the Boyer stator plate in the points cover which was faulty, even though everything looked OK and the spark plugs were sparking.
So my advice would be as I initially said if you are confident that the carbs are ok, star looking elsewhere. Is there any possibility that you could substitute the Boyer ign to exclude fault on your own?
Other things to check are that the ignition is timed properly.
When I rebuilt my Norton 9 years ago, it would "pop" and "bang" when trying to start it but would not fire. There was a spark at the plug, and because I had a non standard carburettor on, I blamed the carburettor and so bought new Amal carburretors with the result........THE SAME!
The problem turned out to be the Boyer stator plate in the points cover which was faulty, even though everything looked OK and the spark plugs were sparking.
So my advice would be as I initially said if you are confident that the carbs are ok, star looking elsewhere. Is there any possibility that you could substitute the Boyer ign to exclude fault on your own?
Other things to check are that the ignition is timed properly.
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kommando said:Oil can
A picture is worth a thousand words.
Thanks Mate. I was once told English is a bastard of a language to learn. Shit I'm no good at it [ thanks for the spell check ] so our friend here is learning fast and well.
Reminds me of something I heard in Wellington about 40 years ago. When there were trams in Wellington, there was a Dutch driver who taught his mate some welcoming words in Dutch. One day a Dutch lady got on their tram, then promptly walloped him with her hand bag. Buggered if I know what he was taught, but I guess you have to be careful what friends teach you.
Hi All,
and thank you for your precious advices.
The timing would be fine because the bike always started at first khick, but i will check it!
The carbs are all new (not the bodies and main jets and needle jets only) but i will replace with new 4 jets now, and i will set the float to 0,8 (0,6 now).
The sparks are new but i will replace with new one.
Then i will heart better the I.E. now on the frame with a joint on one red wire from battery too.
If the bike will not start again i will use a "can oil" into the carbs manifold (how much gas? 10cc is enough?).
Then, i will buy a new Pazon (that i prefer).
Then, i will use the bike only in down hill, could be fine the same!
Ciao
Piero
and thank you for your precious advices.
The timing would be fine because the bike always started at first khick, but i will check it!
The carbs are all new (not the bodies and main jets and needle jets only) but i will replace with new 4 jets now, and i will set the float to 0,8 (0,6 now).
The sparks are new but i will replace with new one.
Then i will heart better the I.E. now on the frame with a joint on one red wire from battery too.
If the bike will not start again i will use a "can oil" into the carbs manifold (how much gas? 10cc is enough?).
Then, i will buy a new Pazon (that i prefer).
Then, i will use the bike only in down hill, could be fine the same!
Ciao
Piero
Peter R
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Piero, 2mm from top of float bowl is correct.
In one of your posts you said that you would change the ignition coils.
Did you use the correct 6volts coils, and NOT the 12Volt coils ? this could explain the weak spark.
You can also test the ignition box.
To do this, disconnect the two wires that go to the stator plate.
With the ignition switch on, touch both wires together for a monent.
This should produce a spark at the spark plugs.
If this works, the ignition box is ok.
In one of your posts you said that you would change the ignition coils.
Did you use the correct 6volts coils, and NOT the 12Volt coils ? this could explain the weak spark.
You can also test the ignition box.
To do this, disconnect the two wires that go to the stator plate.
With the ignition switch on, touch both wires together for a monent.
This should produce a spark at the spark plugs.
If this works, the ignition box is ok.
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