Multimeter help

k80matey

I'm too poor to buy rubbish.
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Numpty Alert!
Couldn’t start the Bumblebee today. Nearly fired up a couple of times but wouldn’t catch. Fresh petrol in the tank, float bowls clean. Strong smell of petrol.
The plugs aren’t too bad but the caps are a bit manky. I’ve ordered new plugs and caps.
I thought I’d do a bit of checking, just out of interest, so I broke out the multimeter.
I only ever use it for checking batteries but wanted to just check the resistance of the old caps.
Set the meter to 2K ohms but no reading. Switched to continuity but no signal either. I’ve tried another couple of caps from my other bikes but just the same result.
I can get continuity checking plugs but no resistance reading either.
Where am I going wrong?
 
The plug caps will have a much higher resistance than 2k - more like 20k
 
I’d say your barking up the wrong tree anyway. It’s very unusual for 2 things to fail together. JJH
 
I’d say your barking up the wrong tree anyway. It’s very unusual for 2 things to fail together. JJH

I’m doing it out of curiosity really, with the hope of learning something.
I’m just fitting new plugs and caps as they’re cheap enough and as a precaution.
There’s probably nothing wrong with either of them but I’d like to be able to know!
Thanks for your help.:thumb
 
I’m doing it out of curiosity really, with the hope of learning something.
I’m just fitting new plugs and caps as they’re cheap enough and as a precaution.
There’s probably nothing wrong with either of them but I’d like to be able to know!
Thanks for your help.:thumb

It’s very easy to check for a spark. Blue is good. Good luck. JJH
 
As you are keen to quantify the resistance for reference,
Start high in m ohms and wind it back to get to a plausable scale,
The meter and leads are ok if probes together o.oo reading,
 
The plug caps will have a much higher resistance than 2k - more like 20k
Plug caps should be 5 Kilo Ohm each"0" when the the leads touch mean a zero ohm resistance connection "1" or no reading usually means an open circuit (not connected) Are the choke mechanisms going on full travel?Is it spinning quickly ??If its labouring then its likely the battery or the starter needing an overhaul
 
The ‘resistors’ in the plug caps are suppressors . The spark is a high voltage but hardly any current so sticking a 5k ohm resistor in the path has little affect on the spark. The plug caps are extremely unlikely to be cause of the bike not starting.
 
The ‘resistors’ in the plug caps are suppressors . The spark is a high voltage but hardly any current so sticking a 5k ohm resistor in the path has little affect on the spark. The plug caps are extremely unlikely to be cause of the bike not starting.

I’m just going to fit and forget the new ones. They’re only a couple of quid. I’m sure if I’d given the plugs a bit of a clean the bike would start no bother.
I’m not really looking for advice on how to get the bike going. Apologies if that’s the impression I gave. I was just puzzled about not being able to get a reading using the multimeter.
I think I’d best just put it back in the drawer.:confused:
 
Why not set the multimeter to read over 20kOhms. Test between the two suppressor caps. They’re 5k each plus another 12k for the high tension side of the coil, equals 22k Ohms & it tests the joints inbetween. Works for me as a quick test.
Still it tried to go you say, so it’ll probably be the carbs at the end of the day.
 
Dud plug caps can make a difference to the way an Airhead starts and runs - I bought a R80 G/S PD for $4200 /2000 quid because it was a vibratory slug which no one could get to start or run properly.
Two new caps fixed 95 % of the problem ----------->
 


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