Hard to start with choke ....

[Blue_SV650S]

A bit odd this one ... my SV has become a bit hard to start (whirs over for ages before firing).

Found the best way to get it started quickest, is to try and start it without the choke on and as soon as it 'catches' wind in some choke.

It won't run/fire properly without the choke BTW.

I have changed the airfilter and it did make it a bit better, but it still has the problem.

Once the bike has been run for a bit (say 60s), it'll re-start easy.

Once it is going, it runs and idles flawlessly BTW.

Battery is pretty new and a proper Yuasa one, the bike turns over nicely, so not suspecting the battery in any way ...

Ideas?
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[crackpotterpi...]

you could start off by checking the choke is operating at the carb end as it should and fully returning when put off
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1990 jc20 nsr125-sold,2003 cg 125-sold currently no bike.........might get another 2 stroke me thinks much more fun

[Ariel Badger]

Try a new set of plugs.
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[Blue_SV650S]

[boundy]

Dont be gay, the SV spark plugs are easy to change. on the front bank, just undo the bottom of the rad and move it forward a tad.




Oh, sorry. I forgot your SV wears a skirt and bra, this is why you should get a proper one.

[Blue_SV650S]

[finpos]

One carb or two?

You might find the choke is doing two things - opening up an enrichment jet and also propping open the throttle a bit for extra air, you'll need to look at the carb to be sure. Possibly the enrichment jet is blocked - you should be able to tell by opening the choke at idle when the engine is warm (and maybe a bit of load on the engine...), it should slow down if the enrichment jet is working, not speed up!

f.

[Blue_SV650S]

Two carbs ...

Right, I had a looksee and BOTH of the choke plungers are working (i.e. the cables are not broken).

If I pull the choke on when the bike is hot/running, the revs 'dip' then pick up .. it revvs to ~4k rpm ....

I am not convinced it is enriching the mixture much though as it rides fine with the choke on ... i.e. not seeming as if it is running silly rich .... but then perhaps it wouldn't anyway!?
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[crackpotterpi...]

mmmmmmmm does sound a bit strange,most bikes if set up properly when warmed up and you put the choke on will as you say over enrichen the mixture and should make them cough a bit...........maybe worth getting the carb mixture/balance checked?
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1990 jc20 nsr125-sold,2003 cg 125-sold currently no bike.........might get another 2 stroke me thinks much more fun

[0l0dom0l0]

i agree with 1930 ariel, just try a NEW set of plugs. might even be worth upgrading to iridium plugs, they are only a couple of quid more expensive and after all your only buying 2...

was it starting with the choke fine before? if so what have you changed since then?

[Blue_SV650S]

Ok, got the compressor on its a55 ... just blowing down the air jets that are by the bell mouth ... lots of fuel came out of various orifices, so I was hopeful ... but sadly NO difference

Ruddy bike ....

I could change the front plug next, but lets face it, is it really going to be that?!!!?!?!?! even if the front plug was poorly, surely it'd fire/start to fire on the rear ...
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[Devans]

I'm no way technically minded, and i kinda have a similar issue, i'm purely putting down too, either too much, or two little fuel.

My bike on cold mornings needs the choke, but too much won't start it, and neither will none.

So maybe your using too much?

And don't blip the thottle either, or even touch it.

Sounds obvious but it's how i have to start my bike.

[finpos]

I suppose you could go down the "all carb problems are electrical" route, in which case I'd be deeply suspicious of the front HT lead and cap which get grief on SVs (especially the old ones which don't have the little rubber flap). You could try taking off the cap and lead and bake it in a low oven for a while (drive off all the moisture) then try a cold start, see if it makes a difference.

In my very limited experience of trying to bump start an SV, I imagine with one dead pot it'll run terribly if at all.

f.

[Blue_SV650S]

The bike runs flawlessly once started (even when cold). I know what the SV feels like when the front plug/plug cap gets wet .. and it isn't that as it runs so well only a few seconds after starting ....

To start it it seems I have to have NO choke ... and it starts to fire pretty readily at that point .. I then 'pick it up' on the throttle and feed a bit of choke on ... which then allows me to let go of the throttle ... it sometimes stalls if I don't get it quite right, and I somply begin the process again.

It is an odd one ...

On a total curve ball ... could it be the valve clearances have closed up?? ... I have never checked them ... but I'd expect it to struggle to idle when HOT if that was the case (and it runs flawlessly).
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[silky666]

[Robby]

Always going to fun to diagnose things like this, particularly if it turns out to be something has no business being related.

Any chance of a blockage or kinked pipe somewhere? Could you have disturbed a carb or the airbox in its rubber when you changed the air filter?
Blocked exhaust - could you have put a load of water down it when washing the bike.

Bad plugs, poor HT leads, bad earth, tight valve clearances, dirty jets.

A modern bike, particularly something in a moderate state of tune, can have a lot of small things wrong with it before it feels like it's running badly on the road. One or a combination of the above things could affect starting.

Change the plugs and spray loads of WD40 over the HT leads, then see if it starts behaving.

[Blue_SV650S]

It isn't something I have disturbed/trapped as I only started fiddling with things like that AFTER it started playing up!!

Anyhoo, after much swearing and bloodied knuckles, I have now changed the front plug ... as I suspected, there is nothing visually wrong with the plug (ok so it is a bit mucky on the outside, but the important bits (electrodes) are in good condition) ...

I'll give it a true 'cold start' tomorrow and report back ... but I think we need to start looking elsewhere now plugs have been eliminated from the equation ...
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[Blue_SV650S]

Rule number one reinforced once again!! ...95% of all carburation problems are electrical ...

I need more cold starts to confirm it, but after sticking the new* plug in there yesterday - I'll be rogered sideways with a banana - it actually started fairly rapidly on full choke when I tried it today!!!

So Mr Silky666, when is the last time you changed your plug!?!?!


*I say new, it was a 2nd plug and of the wrong heat grade and 'variant' (supposed to be a CR8E slotted in a used CR10EK) but it seems to have done the trick
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The purpose of life is to fight maturity.

[silky666]

[Blue_SV650S]

[Wafer_Thin_Ham]

You have to be the tightest rich person I know Blue (Including your oil saving escapades).

Go on, treat it to two new plugs. It deserves it.
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[Blue_SV650S]

[Blue_SV650S]

Rule number one reinforced once again!! ... 5% of all carburation problems are carburation problems!!
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[Howling TerrorOutOfOffice]

Well chaps, i hope you've dished good vibes to our resident chilli muncher.

Rule #0.5 Teacher knows best


Pat
Shamelessly posting drivel since 2008
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[Blue_SV650S]