Friday Afternoon / Monday Morning bike - HELP!!!!

[MavUK]

Hey All,

Well just a few weeks after getting the SV back on the road (A lake in the tank and carbs was the reason last time, it now has a new filler cap and lives under a bike cover to stop this happenning again) I was nearly stuck again this morning...

Travelling at 60mph when suddenly it's very quiet and I'm starting to slow down, twist the throttle (reflex response to slowing down I think :) ) and nothing. Not good in the outside lane of the motorway...

By the time the bike slowed to about 45ish she suddenly started up again, was a bit rough for a few secs, then back to (hopefully) normal.

I'm thinking it can only be one of two things - fuel delivery issues (Tank is almost full, so plenty in there, even if it can't get to the carbs / engine) or ECU is on it's way out - as it was both cylinders and totally dead, not missing or anything, just absolutely nothing...

Really starting to get me down now. I love the SV, but with a 140km per day commute I need something I can have faith in...

Anyone got any ideas on what it could be? Or how I can fix it... Don't think I can really afford to start looking for another new bike after only a year of having this one...

TIA

Stu

[mattSV]

If you have had the fuel tank up, check that the fuel lines underneath have not been caught/kinked when you dropped it back down.

My dealer trapped a hose after my first service, which gave me the same symptoms that you described.

HTH

[MavUK]

Cheers - hope this is the same... I'll have a check when I get home.

Thanks

Stu

[SteveR]

Any strange lights / conditions on clocks ?
I would guess the speedo was reading normally but the tacho was zero.
I wouldn't expect any other lights on though.

You might want to check sidestand cutout - is the sidestand held securely, and is the switch operating correctly ? Apart from that, I'd look for chafed / frayed wiring

[mysteryjimbo]

Ermmmmm two words.......


CARB



ICING

:lol:

Possibly. If it was very cool (3-9c) and damp, theres your problem

[MavUK]

Any strange lights / conditions on clocks ?
I would guess the speedo was reading normally but the tacho was zero.
I wouldn't expect any other lights on though.

You might want to check sidestand cutout - is the sidestand held securely, and is the switch operating correctly ? Apart from that, I'd look for chafed / frayed wiring

Sorry forgot to metion that - nothing else 'seemed' strange. The taco, strangely enough kept reading. I did a chack after to see how long it takes to return to 0 after I let go of the throttle in neutral and I think when the engine died the taco dropped in line with the engine speed, not with the as though it was suddenly getting no input.

I'll give the side stand a check at lunch and post back on it - but I think it's secure.

Stu

[rictus01]

Apart from that, I'd look for chafed / frayed wiring

Seeing as you've got the Classic shaped one, have you checked the rear subframe part of the loom ? lift it away from the bike as it is known to ware through on the inside. this can lead to some very strange things happening :shock:

Cheers Mark.

[Sid Squid]

Ditto the above.

And:

Check the filler well drain isn't blocked and you haven't got water in the tank again, it's not the filler leaking that gets water in the tank, water lies in the filler well and when you open it it drops into the tank, it rarely looks like there's water 'rounf the filler as it's all dropped into your fuel...

[SteveR]

Sorry forgot to metion that - nothing else 'seemed' strange. The taco, strangely enough kept reading. I did a chack after to see how long it takes to return to 0 after I let go of the throttle in neutral and I think when the engine died the taco dropped in line with the engine speed, not with the as though it was suddenly getting no input.

I'll give the side stand a check at lunch and post back on it - but I think it's secure.

Stu

If your tacho was still showing revs, then I think we can discount ignition problems - and the sidestand switch. That leaves fuelling as the main suspect. Check not only fuel lines, but also the vacuum line to the fuel supply 'switch'

[MavUK]

Sorry forgot to metion that - nothing else 'seemed' strange. The taco, strangely enough kept reading. I did a chack after to see how long it takes to return to 0 after I let go of the throttle in neutral and I think when the engine died the taco dropped in line with the engine speed, not with the as though it was suddenly getting no input.

I'll give the side stand a check at lunch and post back on it - but I think it's secure.

Stu

If your tacho was still showing revs, then I think we can discount ignition problems - and the sidestand switch. That leaves fuelling as the main suspect. Check not only fuel lines, but also the vacuum line to the fuel supply 'switch'

OK - was my thinking...

If my scotoiler is working does that mean I can discount the vacumn line to the fuel switch - as it's hooked into this.

Stu

[Halonic]

I get this on mine (naked Y-model curvy)

about once a month, always when I least need it (ie always engine breaking, generally approaching something at speed)

I have found that you get a warning, one sputter on the downshift. I have a sneaking suspicion its something to do with fueling and the idle rate as it only occurs on a closed throttle after the bike has had some "abuse".

I have found that getting the throttle open again, even a bit, prevents it from actually stalling.

So its either airflow, fuelling, or not sparking ( I would expect unburnt fuel with that last one and there isnt any soo....)

I was hoping a freer flowing airfilter and a new end can may improve things but havent the cash to do it.

Aside from that, everything else is clean / doing what its supposed to do

BTW happens a lot less using Texaco, Shell or Esso High RON fuel (if ever) but more regularly on BP High RON and normal RON crap

[MavUK]

OK checked last night and the fuel lines seem to be fine (But will check again at the weekend when there is more light)

As for the water 0 I don't think that's it this time as it doesn't stand in rain any more. The shop tested the drain pipe and said it flows freely, they alos said they tested the filler cap and it also flowed freely, explaining the rust on the inside of the filler cap (I suppose I should have noticed this earlier :) )

Anyway, just some more info to see if it sheds any more light on the issue...

Not done the whole stopping thing again, but... When riding at 100kmph for 30kms or so if I pull on the throttle it's very hesitant, then seems to sort itself out (in a sec or so) and pulls normally. Would this just be carb icing? I've had that in the past and it normally causes it to be a pig when slowing down for traffic lights and I've not had this yet this autumn.

TIA again folks,

Stu

[mysteryjimbo]

Sounds like carb icing to me.

I used to get on the SV after doing a similar distance.

[Captain Nemo]

Sorry forgot to metion that - nothing else 'seemed' strange. The taco, strangely enough kept reading. I did a chack after to see how long it takes to return to 0 after I let go of the throttle in neutral and I think when the engine died the taco dropped in line with the engine speed, not with the as though it was suddenly getting no input.

I'll give the side stand a check at lunch and post back on it - but I think it's secure.

Stu

If your tacho was still showing revs, then I think we can discount ignition problems - and the sidestand switch. That leaves fuelling as the main suspect. Check not only fuel lines, but also the vacuum line to the fuel
supply 'switch'

not neccesarily, if the bike is moving the tacho will still show revs even if the engine has stopped, because the engine is stilll spinning as its still connected to the gearbox, just cos the ignition dies this wont stop the tacho giving a reaading

[Red ones]

Wasn't raining at the time was it?

[MavUK]

Wasn't raining at the time was it?

:) Thankfully not

Stu