Electrical problems on a vfr800??

Hi guys, been a long time since I’ve posted on here, been far too much of a part time rider these last few years, anyway… :slight_smile:

I got a vfr800 2002 and it won’t start. Tested battery and that seems to be holding its charge at just over 12volts. Starter motor isn’t clicking, when hitting the starter, it sounds like the engine is trying to turn over slowly but there’s no power it seems, horn stops working when engaging the starter and all the lights dim. Only time I have got it started recently is by jumping it from a battery charger plugged into a mains power supply, and then it started instantly, so I’m thinking the power is not being diverted somewhere from the battery, but I know next to nothing about electrical stuff, any tips or pointers? am I write in thinking its electrical? couldn’t be a dodgy spark plug or something? I’m not that mechanically minded and I don’t want to start taking bits apart for the sake of it. I’m a bit stumped about what to look for first. the earth looks to be connected well to the engine frame, but without removing the petrol tank etc. I can’t get at the bolt to clean it up and tighten…

Probably unrelated but the left indicator is a bit temperamental, could there be a short there causing a drain on the power supply?

Anyway, any tips much appreciated, I got to ride down to cornwall in 10 days, and i really don’t fancy taking a bus… :wink:

Do you have a multimeter? Electrical problems can be a complete arse, and (unless you’re me_groovy) you’ll have to end up with a working knowledge of how DC circuits work if you’re to do any diagnostics at all (it’s not tricky, but might be boring). You may decide that for the expediency it’s worth paying to make this someone else’s problem.

If not, read on! :slight_smile:

The spark plugs don’t generally have much to do with the rest of the electrical system, so it’s not those. The problem is somewhere in the bits that run the starter motor, and the fact that it’s affecting everything else suggests it’s a common component - generator, reg/rec or battery.

It sounds mostly like the battery’s at fault - when you say it’s holding its charge, how long does it stay at 12V for? If you leave it on a charger for a few hours it should be full. Disconnect it and measure the voltage, then wait for about 12 hours and measure the voltage again to see what the difference is.

Get the engine running and test the voltage across the battery with the bike at a fair bit above idle. As the revs climb so too should the voltage up to about 14.5V. If it gets that far then your generator’s probably fine, and if it stops rising at 14.5V then your regulator/rectifier’s probably okay.

Also, with the ignition on but the bike off measure the voltage between the negative terminal on the battery and an exposed bit of metal on your starter, and also between that terminal and any bit of unpainted engine.

What’s the recent history of this bike? When was it last working, was this a sudden change or have you had odd electrical gremlins for a while?

Thanks for the reply. Yeah I’m trying to save a few quid, and obviously with it not starting, getting it somewhere is a bit of effort…

I’ve tested the battery using one of those oxford battery maintenance thing that show the voltage, and charge it back up to optimum when needed. At first I was convinced it was just the battery as it had been left standing for a good few months, and after jump starting it, I rode it a good 20 mile trip up and down the motorway, turned engine off, went to turn back on and same symptoms, no power. Plugged into my charger which showed the battery was holding a little over 12v, so i’m a little cautious about buying a new battery straight away. I don’t have a multimeter though, so it might be worth getting one of them. Could it still be the battery based on those symptoms?

Bike has always been notorious for draining the battery, but I put that down to aftermarket heated grips and the vfr having quite a lot of gadgets built in, but it’s normally been fine as long as its been ridden regularly, which to be fair it hasn’t been for the last 8 months or so.

When I had electrical issues on my vfr it was the reg/rec so I got an upgraded one. It used to work ok for a while then stop intermittently

I’m a bit of an electrical numpty- but Halfords used to do a small charging circuit tester that indicated ( to whatever degree of accuracy) Undercharging, over-charging and battery leak-down. Three of my previously owned Honda’s had regulator failures that cooked the batteries. New reg/rec & replace battery was worked for those.

It’s highly likely to be the reg/rec because it’s a Honda and their reg/recs have a tendency to go wrong. The battery’s probably also bad, though, as a result. If you’re intending to do much more fixing of electrical problems a multimeter’s handy generally, but one of those charging circuit tester’s ought to be enough. Any problem in the charging circuit is hugely more likely to be reg/rec than stator (and the reg/rec is cheaper and easier to replace).

The only thing I know about VFRs other than that they have a V4 engine configuration is that reg/rec is a common fault. Every time one pops up on here with electrical issues that seems to be the root of the problem.

Cheers guys, guess thats something to look at then. Would a faulty reg/rec still prevent a bike starting with a charged battery though? I left mine off charge for 12 hours, plugged back in and hadn’t lost any charge at all…

No, but a faulty battery might. What was the voltage when you tried to start it?

just over 12v

after hitting the starter and it failed, dropped to around 10 /10.5

When my reg/rec failed the bike would run once going but drain the battery so when I stopped it wouldn’t start. As it got worse it started cutting out on the M25 the dials would bounce around and I had to pull the clutch in and out to bump start it. After numerous call outs from RAC I got a new upgraded one from David Silver no problems since. It’s a lot thicker so I had to find longer bolts.

Yeah, I think you’ve been riding around for a while on a bad reg/rec and that’s ruined the battery. Hitting the starter would cost fractions of a volt on a battery with normal capacity.

Cheers guys, well I got a new battery as I’m pretty sure it’s knackered anyway, next job will be testing the reg/rec and take it from there, are they hard to replace if it comes to it? If it’s more than a few bolts and spanners then it’s probably out of my league :wink:

It’s 2 bolts and a straight plug in, the hardest part was getting the plastics out the way.

You can’t meaningfully test reg/recs - there’s some tests you can do, which are just to check that each component has the right resistance. If these tests fail then you know the reg/rec’s bad, but if they pass that doesn’t mean you know that it’s good.

Well I’m going to get my hands on a multimetre over the weekend, so I’ll do the above tests you mentioned, assuming new battery fires the engine up which I’m sure it will… If nothing flags up then I’ll take it to someone who knows what they’re doing to test it more extensively I guess, the battery has drained itself a couple of times from sitting around too long, so I’m hopeful it’s as simple as my own bas care of the bike and not another component… but I also don’t want to wreck another battery on that assumption. I miss my old bandit, no electric to go wrong on that!

Update for anyone interested / future people searching for similar faults.

Replaced battery, everything seemed normal when checking, and 1000 miles out of town (Cornwall and the mendips, which incidentally are great places to burn some petrol…) battery still seems to be holding correct charge and hasn’t dropped any, so with a bit of luck it was a dodgy battery / one that I’d overcharged a couple of times…

Lesson to be learnt

Don’t leave a battery standing on a bike for too long without a means to keep it topped up.

You may find that you’ve just replaced the battery with another one that the reg/rec will cook. It can take a good while, but keep an eye/ear out for the battery losing charge and be prepared to still need to replace the reg/rec.

^^what he said, I did the same with a new battery, it lasted a month, I’d check what type of reg/rec you’ve got and it’d be worth upgrading before killing another battery, I learnt the hard way(pissing down on M25)

Reg/Rec. Had that issue on a VFR750. Also needed a new battery.