Serious starting and performance issues - any advice welcome.

My 2000 model SV650S has had some real issues recently. Beginning just before Christmas, during the cold snap, it had trouble starting. It would fire up for a brief second but then cut out again, and I'd only get two or three more tries until the battery acted like it was drained. I couldn’t use any choke as it acted like it was flooded and wouldn’t fire up at all, and I couldn’t even touch the throttle as that made it cut out as well.

The only way I found to get the bike running was to keep the choke in, leave the throttle alone and keep my finger on the electronic starter until the engine had turned over enough times to warm it up slightly. Even the smallest amount of choke and it wouldn’t fire at all... just kept turning over. Zero choke and it would fire up although cut out again if the electric starter was released or the throttle was touched. About a minute of this and the throttle could be very slowly opened a little and the starter released but once the throttle started to open to get the revs up it really started to pop and bang.


It got the bike going but must have been absolutely destroying the starter and God knows what else.

My dad thought it might be a misfire or that one of the cylinders wasn't firing at all as when I popped round to his he said it didn’t sound right, but like I said before, once running, there's were no problems.

I checked over the bike and everything seemed in order, so took it into the mechanics. They found the battery was duff, which annoyed me as it was only a year old. They replaced it and it fired up first time, although it was still struggling a little directly after ignition.

No problems until after Christmas, when I needed to use the bike to make a couple of fairly long distance journeys – 2 round trips of 230 miles. The bike ran fine until I got to the dual carriageway. I got it up to a cruising speed of 90 straight away in top gear and for five minutes it ran perfectly. Then I noticed the speed reducing and my revs were dropping, even opening the throttle more didn’t stop it. The revs eventually levelled off at 6,000 with a top speed of just under 70 and I could not get anything else out of it, so had to head back home. All performance was gone, including acceleration which was slower than the surrounding cars.

I got the bike picked up by the mechanics and they went over it top to tale – replacing the sparks and cleaning up the carb heaters, and also found that the linkage between the two cylinders was loose so tightened it up. It worked again perfectly.

Until this week. The starting issue has begun again – it struggles more and more each time to keep turning over after ignition and has almost stalled a couple of times. And then this morning on the dual carriageway acceleration up the slip-road was really sluggish and revs topped off at 6,000 again.

Okay the bikes 8 years old and had some modifications made to it, but it’s done less than 20,000 miles, and my original, identical SV did 50,000 miles in half the time with nothing like this happening.

Does anyone have any ideas what the problem could be?

Thanks in advance.

[pmapp]

I'd hazard a guess at it being carb related.......

Sticky choke plungers/cables ???

[jambo]

I'd say you're chasing at least 2 issues here, it's important to look at each symptom, and check they are linked.

1) It's cold at the moment, in cold weather the battery's got less go, the oil is thicker and a bigger ask is being made to turn the bike over, so check the connections to the battery, the main earth, the starter solenoid and the starter motor itself are clean (take them apart, use a brass brush) and use a little oil or grease on them to help keep them that way. Rubbish electrical connections won't help the battery turn the motor any.

2) Check the choke plungers aren't stuck, water gets down the choke cable to a Y-piece splitter to the left of the engine, runs down to the choke plungers (usually the front carb) and sticks them on. The fueling is now rubbish. A sooty plug on one or both cylinders can be a symptom of this. It's well documented, take the plungers out, clean them up, oil the cable and pack the Y-pice full of grease.

3) When you're doing fast A road miles in cold temperatures, with high humidity, you're in perfect conditions for carb-icing. Yes the SV has carb heaters, but they're a bit pants (like most carb heaters). Use a fuel additive such as Silkoline Pro FST, or try using a Super unleaded like Shell V-Power or BP Ultimate. Makes a difference to carb icing but won't get you any more power

HTH

Jambo

Thanks. I should mention however, that I only use Shell V-Power and and top up every tank full with 100ml of Silkolene Pro F.S.T.

From the mileage I did on my old SV, I'm well aware of carb-icing and how to fix it, and what I've got this time is definitely not caused by carb-icing.

[jambo]

Hummm, well then it's a case of tying it down to fuel or ignition then. The fact the choke kills it would make me suspect fuelling rather than ignition though. I'd still check over the electrics for the starter motor and main earth as this can make it harder to start.

just a question relating to this, do you have to take the air box off to get to the plungers? any pics of this area would be good.

silly question i know, but how do you get the airbox off? + do you have to take the rad off to get to the front spark plug?

[jambo]

Tank up on it's hinge & stand, airbox off and you can see the cable on the left. If the screws holding the plungers are stuck in (they may well be) please note they are made of cheese, and you will want the carbs out and a good set of screw drivers (probably off a ratchet) to get them off.

Jambo

[Biker Biggles]

Apart from the fueling issues,your bike has destroyed the first one year old battery and appears to be doing something similar to the present one.I would get a multimeter and check the charging system.Do a search on here to get the readings you should have and see if your alternator or regulater are working properly.