Author Topic: Sluggish Bonneville  (Read 4953 times)

Offline Robbell

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Sluggish Bonneville
« on: April 15, 2011, 01:45:05 AM »
Hello all,
I've just dragged out my '68 Bonneville after it's winter sleep.
I put some fresh fuel in it and it started up good and sits and idles smooth.
Problem is, it's lost its zip. It's sluggish. It acts a bit like it's going uphill in top gear. I've had it out for a couple of runs but it doesn't seem to be getting better as the cobwebs blow out.
I pulled the plugs and they look fine. The Amals only have a couple of thousand miles on them.
I'm wondering if this could be the symptom of weak coils. I put Pazon electronic ignition on the bike four years ago but left the original 1968 coils in place. Any opinions?
Does anyone know what the resistance reading should be on these coils?
The other more disturbing posibility is that there is a compression problem. I don't have the equipment to test that right now and am hoping that's not the problem.
Thanks

Offline Rex

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Re: Sluggish Bonneville
« Reply #1 on: April 15, 2011, 08:38:39 AM »
It's not the coils. I'd check the ATD was working properly and not seized, first off.

I suppose you've checked the tyre pressures and that a brake isn't binding?

Offline Goldy

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Re: Sluggish Bonneville
« Reply #2 on: April 15, 2011, 05:58:46 PM »
It could be the petrol if it,s been left standing because unleaded fuel "goes off". I would try draining the fuel and put in fresh petrol and see if that makes any difference. All the best.

Offline TBS

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Re: Sluggish Bonneville
« Reply #3 on: April 15, 2011, 06:22:57 PM »
You should be able to stand on the kickstart for a few seconds on each cylinder if you weigh around 13 stone which is a good indicator for a compression check. However if it was fine before the layup, then I would expect there is a carb problem, so the best way would be to send the carbs off for ultrasonic cleaning as they are probably gummed up if you didn't drain them.

Offline raptorkev

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Re: Sluggish Bonneville
« Reply #4 on: April 15, 2011, 07:09:52 PM »
i have the paxon fitted and they do recomend 6v coils but if it was fine before lay up probably something else

Offline Robbell

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Re: Sluggish Bonneville
« Reply #5 on: April 17, 2011, 12:39:25 AM »
Thanks to everyone who chimed in to help me with this little problem.
The mystery is now solved.
My son, being the good lad that he is, decided to give the old girl a bit of a cleaning for me.
In his youthful wisdom he decided that using a leaf blower to dry it off after a good wash was a brilliant idea.
Some water must have found its way somewhere where it shouldn't have because after it had been given time to dry out thoroughly she regained her strength.
I decided to put in a new set of plugs and am trying out the NGK iridium plugs.  Might just be my imagination but there seems to be a bit better throttle response and a bit steadier idle. Can't say for sure if they are worth the extra money but time will tell.
Anyone else given these a go?