This was originally published on benscomputer.no-ip.org in 2009
mentioned previously, the bike was due into the Garage on Friday
to sort out the charging problems that it seems to have developed. The
symptoms also included a misfire at low revs (anything below about 2500
Unfortunately, the Garage found some more urgent repairs that needed doing (Brakes had seized again, amongst other things) so I hit my budget ceiling before they could really take a look at the original problem.
So on Saturday, I got out the toolkit again and had a look.
completely forgotten to buy a new relay for the bike, so I started from
scratch again, checking the Regulator/Rectifier, the generator and the
charging voltage (I admit I did initially forget to disconnect the lead
I had put between the R/R and the battery, but realised as soon as the
Multimeter said that the battery was charging.
There was still a misfire at lower revs, and keeping the revs up whilst braking puts one hell of a strain on your right wrist. This is an issue that needed sorting, so whilst I thought about what the next step might be, I pulled the plugs. The Plug from the rear cylinder looked pretty much like they do when they have been used, albeit a little black. This is normally a sign that the engine is running rich, but as I wasn't entirely sure that the cylinder was firing every time, I kinda figured this was par for the course.
But when I pulled the front plug, I couldn't believe the state of it.
The thing about spark plugs is that no matter how long they have been
in an engine, the external section always look pretty clean, yet this
one was crusted with rust, dirt and all manner of other krud.
In fact it was so bad, that the sealing ring wouldn't sit flush with the rest of the plug (you can just about see it in the picture). Obviously I swapped both plugs for new ones. Once I had re-connected everything, using lots of grease to help seal the front plug, I hit the starter. She ran fine, so I went back to sorting out the charging system. Except.... the battery was charging without my additional wire connected.
My only guess is that between them, the plugs were demanding so much from the Stator that there just wasn't enough trickling through the Regulator/Rectifier, the resistance of the factory cabling between the R/R and the battery is much higher than in my lead, so perhaps this is why the additional lead made a difference.
The boot at the end of the spark plug cap was pretty knackered on the front cyclinder, unfortunately I didn't have a spare,s o for now I've had to put it back in. I'm guessing thats probably why the problem came back this morning after I had washed the bike, but a quick dose of WD40 seems to have returned the bike to a running condition again. Once the bike shop opens on Monday I'm going to grab a new rubber boot, and a Fenda Extenda which should hopefully stop this problem from re-appearing the next time it rains.
So if you are having problems with the SV, it appears Spark plug well can affect much more than you would initially expect, so it's probably worth grabbing a few CR8E's to keep as spares. Make sure Pipe Cleaners are on your consumables list, that way you can keep that drain hole clear, and a Fenda Extenda will do no harm!
There are probably a few who will read this and say, "Spark plugs should be the first thing you check!" but I'd guess they have probably never worked on an SV. Technically the statement is right, but the front plug is an absolute nightmare to get to, especially on the faired version. I've still got grooves in my hand from the radiator yesterday, there just isn't room to get your hands in there, and once you do everything is done by feel. It's actually easier to check the Carbs and the R/R than it is to change one spark plug!
Still, despite that, it should be the first thing you check, as it turns out the gaps would have needed adjusting on the old plugs had I not replaced them.
On the plus side, I learnt a hell of a lot more about the SV's electrical system than I would normally need!