RICK FIXES MUSEUM BIKE
Our man Parkington enjoyed doing undercover servicing at the NMM so much, will he ever return to CB?
During my visit to the National Motorcycle Museum, I got involved in fettling one of the exhibits myself. It wasn’t as in-depth a job as the three Rudges I’ve taken on (see page 148), but it did provide more instant satisfaction.
One of my missions for the visit was to road test the museum’s Triumph Bandit (see page 158), and Wes Wall, a member of the museum’s workshop team (see page 156) pointed out that the bike had a slight misfire. He’d drained the carbs to clear out any stale fuel or dirt, but it didn’t seem to have cured it. Riding round the car park, it wasn’t too bad – but opening it up out on the road, the Bandit soon cut onto one cylinder so I limped back. Wes was busy preparing the museum’s Royal Enfield GP5 racer for a Youtube video we were making in the afternoon (see www.classicbike.co.uk/videos). I’d sprung the request to dig out the twostroke racer on Wes at the last minute and it was reluctant to start – Wes found that the fuel hadn’t been drained last time the bike was started and the GP carburettor
had gummed up. So while Wes set about stripping the GP5’S carb, I thought I’d take a look at the Bandit – after all it isn’t often you get to work on a rare prototype. Well, unless you’re Wes, maybe...
The right cylinder was the problem; the plug looked OK, if a bit black, but a misfire leaves unburnt fuel in the combustion chamber that can cause that. In any case, Wes had already drained the carb and it felt more like an ignition problem than anything to me. So my first stop was the points. Like other Triumphs, the Bandit’s points are driven off the camshaft – but unlike other Triumphs the Bandit is a doubleoverhead-cam engine, so the points housing is on the cylinder head. Typical of a British twin, there are two sets of points, two condensers and two coils, so given that only one cylinder was affected, one of these was a likely suspect rather than something common to both, like the ignition switch or a dodgy fuse holder.
Flicking open each point in turn with my penknife soon revealed which set fired the
right cylinder. A fat spark suggested points and plug were doing their job, but the misfire was definitely worse at high revs, suggesting possible condenser failure. Lifting the seat, I was pleased to find the condensers and coils readily accessible. Since it was unlikely for both condensers to fail at once and they were side by side, the obvious test was to swap the wires around and see if the misfire also switched sides.
In the event, a ride round the car park showed that the misfire had gone, so removing the wire from the condenser must have cleaned up a dirty connection. Such problems are inevitable with bikes that are not in regular use – even in a controlled environment like the museum. They’re simple but can take time to trace. At least I’d saved Wes the bother this time – and in the meantime he’d got the Enfield ready.
I think I could get used to a job like this...