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[JoshN]

Hi all,

I have a Bullet 500 B5, bought October last year with about 3500 miles on the clock, ridden daily and had no problems riding it all during last winter, or indeed for the past year...

In the last 6 weeks the Bike has developed a problem whereby when at the top end of a gear (pre gear change) the bike starts to jerk and acceleration is a real struggle - its definitely a worse problem in lower gears and definitely worse in the cold. Bike is also not starting up and ticking over with the same energy than previously - it does start but there has been a couple of times where it has cut out.

As I say I rode the bike all last winter and had absolutely no issue so I can't think it's cold alone - must be an issue exacerbated by cold?

I took the bike down to GV Bikes in Taunton and they changed the battery and spark plugs and I managed to ride the bike back to Bristol fine, all ok. However, once the bike had been sat for a few hours (until about 9pm) and again this morning - the same problems arose.

I'm not much of a mechanic but this has got both myself and the chaps at GV Bikes stumped! Maybe something to do with fuel supply? Any ideas?

Any help would be much appreciated.

[Rattlebattle]

Is the sidestand ignition cut-off switch still in place? A lot of owners, including me, disable the switch because sooner or later it causes the sort of issues you have. Other possibilities include dirty connectors for the various sensors, which need to be separated, cleaned and treated with dielectric grease to keep out moisture. The other common issue is the small wire that connects to the battery negative terminal. What often happens, particularly on the C5 on which the battery cables are under too much tension, is that the wire breaks and only makes intermittent contact. This is only evident by peeling back the sheathing. Less likely on a B5; my money is on the sidestand switch, which cause problems on other makes too. I assume the MIL light doesn’t light up when the engine misfires? If it does it would be worth checking for stored fault codes, but I’d look at the other stuff first. I assume that the spark plug is OK and is the right grade. As the battery has also been replaced (not sure this was necessary if it started on the motor ok), it shouldn’t be that. Better use an RE dealer than one with no knowledge of the foibles of these bikes. Good luck.

[Mark M]

First let me say I know nothing about the Fuel Injected Enfields. However, our car recently developed a fault not unlike this which turned out to be the Lambda sensor (O2 sensor?) in the exhaust. I think there is only one sensor on a B5 rather than the 2 on our Subaru Forester but the symptoms were very similar. Does that sound likely EFI experts? Apologies if this muddies the water!

REgards, Mark

[Rattlebattle]

Unlikely, though possible. The RE uses a narrow band sensor; cars use wide band sensors soare able constantly to adjust. More modern bike systems do too.

[Mark M]

Would a MIL diagnosis help here? I have had some experience of using the simple diagnostic code devices to unravel a fuelling problem on an MX5 and discovered that they are of limited use sometimes, unable to explicitly identify some fuel/air mix problems. Reading about others' experiences with the MIL system on Enfields I was wondering how much faith to put in what it says?

REgards, Mark

[Rattlebattle]

The MIL is better than nothing for current faults (no pun intended) though it’s not as accurate as DOL used by RE dealers. I doubt that it would be IV much use here if the light isn’t on and anyway the OP claims not to be that knowledgeable. I have used it to diagnose a faulty sensor but I have to say that it’s nowhere near as useful as TuneEcu I use on my Triumph. I still think it’s an electrical connection issue or possibly the TPS or its connector. It could also be a partially blocked injector.

[Mark M]

Thanks, I'm unfamiliar with these systems as used on motorcycles and wanted to gain a bit more knowledge. In the past I've found diagnostic systems lead to a rather literal fault identification process which usually means replacing things until you hit on the faulty item. For me they haven't been much good at identifying more complex problems or the sort of faults you inevitably get on older machines due to the ravages of corrosion or wear and tear. Or previous owners!

REgards, Mark

[stinkwheel]

So they changed the battery and sparkplugs and the problem went away. You rode it for a bit, parked it overnight and the problem came back?



I would be asking searching questions of the charging system. Such as what the resting, idling and revving battery voltage is and if all the charging phases are functioning properly.

[vince]

Hi, this sounds similar to a fault I had. The regulator was defective and boiled the battery dry causing all the charge to go into the coil. The symptom was like the engine was massively over advanced and wanted to run backward. Now a change of battery would cure it until thats boiled dry. Vince.

[Jack the Lad]

Sounds like a regulator/rectifier problem - the most likely cause of a faulty charging system. Easy enough to check with a multimeter and lots of 'how to' tutorials on You Tube.