Electric start clicks when engine is kicked over

Hello everyone .
Ive just purchased a 1975 850 electric start commando that has been stood for a while and i need a little advice please.
The problem if it is a problem is that when the engine is turned over with the kickstart there is a clunking sound from the primary case , ive been told it is the sprag gear on the starter that is making the noise and that when i fit a battery this noise will dissapear , is this the case has anyone else come across this noise before ????
Also is there a way to prime the auto chain tensioner as it seems a little soft??? any advice will be greatly appreciated
regards Tom

tommy666bikes said:

The problem if it is a problem is that when the engine is turned over with the kickstart there is a clunking sound from the primary case , , is this the case has anyone else come across this noise before ????

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As the crank loses energy, it is often brought to an abrupt halt by the cylinder compression which pushes the piston back down the bore slightly, briefly rotating the crankshaft backwards as it does so and that can engage the starter sprag momentarily before the crank finally comes to a stop, and if that is the noise you are hearing (a clunk followed by a brief whirring noise) then it shouldn't be a problem. However the clunk could also be caused by the tensioner not being primed.

tommy666bikes said:

ive been told it is the sprag gear on the starter that is making the noise and that when i fit a battery this noise will dissapear

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I would tend to disagree that the noise will disappear, as it may still occur when kickstarting or as the crank comes to a stop after the ignition is switched off.

tommy666bikes said:

Also is there a way to prime the auto chain tensioner as it seems a little soft??? any advice will be greatly appreciated
regards Tom

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The only way to manually prime the tensioner is to remove the primary cover and fill the tensioner reservoir whilst operating the plungers.
From personal experience, I would recommend that you use 20w/50 engine oil in the 850 Mk3 primary case as I found the tensioner did not work properly with ATF in the primary. It's hardly worth going to the trouble of manually priming the tensioner as the oil will probably all drain out again within a few hours.

The sprag clutch does not make a clunk sound when it is giving up the ghost. It sounds like a garbage can being run against a back alley brick wall. Check your primary 20-50 oil level. You're getting off easy.

Hi Thank you for the replies they are very helpful , i will use 20/50 oil in the engine and primary case,i guess ive been worrying about nothing as it seems this clicking noise is normal , when i remove the spark plugs and kick it over the noise dissapears so it looks like it is compression related . the chain tensioner will prime itself is that correct??
regards Tom

tommy666bikes said:

the chain tensioner will prime itself is that correct??

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If the the revs are kept up to around 1500-2000 RPM after starting then the tensioner should re-prime itself in about a minute or so.


When the electric starter is turning the ant-backfire device can occasionally make some pretty horrendous grating noises too if it operates, but it's nothing to worry about.