RS 125 WONT START!/HELP?

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

Hi all,
help please!
went to have a wee run out to get fags but bike wont start!
i have only used it a few times recently as i was putting on a bigger carb & changing exhaust.
but after re-jetting & a little fiddling about, seemed to be running good.
i have only used it for a few short journeys & a couple of blasts up dual carriageway for test runs.
done the usual, checked battery - its all charged up.
whipped plug out , noticed it was black & wet??
so changed it ,
ran for a few seconds then cut out.
still wont start.
sounds as if its trying to start as it splutters/coughs but wont fire rite up!
anyone any ideas?
last thing i did was turn up the oil pump as i was concerned that i wasnt burning enough.
could i have turned it up too much causing plugs to foul?
or is it something else entirely?
all ideas/advice welcome!
i was planning on using it for commute to work in morn!
just as well i havnt sold the honda yet!
cheers,
GAZ

TUG · World Chat Champion Joined: 12 May 2007 Karma :

um, wet and black? maybe it is the oil that you've turned up to much? or its flooding?
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Haz ER-5, innit!

matt_uk · World Chat Champion Joined: 19 Jul 2006 Karma :

petrol?

petrol switch is off?
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stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

TUG · World Chat Champion Joined: 12 May 2007 Karma :

well maybe your jet is too big? or you need to set the carb up to the jet you've selected by changing the idle mixture and the needle height? but it could just be the oil fouling your plug.
____________________
Haz ER-5, innit!

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

TUG · World Chat Champion Joined: 12 May 2007 Karma :

if you change the needle height you need to lean it out by raising a notch to the top (thick end) and lean out your idle mixture is the brass screw on the carb, not the idle that controls the revs, tho it could be flooding due to low idle? try putting it to a decent idle it could be just as simple as that or a shit plug? how did it run when you tested it?
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Haz ER-5, innit!

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

Kiss_My_Rs · Scooby Slapper Joined: 13 Sep 2006 Karma :

Sounds like your main jet is to big to me.
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stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

Kiss_My_Rs · Scooby Slapper Joined: 13 Sep 2006 Karma :

How are you starting the bike?

You using the throttle and choke?

Should be able to start it just on the button.
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Main jet will not affect starting. Affects full throttle, or close to it.

Needle affects the mixture through most of the range.

Idle mixture screw affects the mixture on a closed throttle / virtually closed throttle.

I would doubt it is the oil pump as it would need to be swiming in oil to kill a new plug that quickly, in which case it would have barely run before.

Personal guess is that you have flooded the engine. Maybe the needle valve is sticking, basically allowing the petrol tank to empty itself through the carb and into the engine while you are parked.

All the best

Keith
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jimpuntoy · Nova Slayer Joined: 06 Dec 2005 Karma :

u need the choke mine wont start from cold without it
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TUG · World Chat Champion Joined: 12 May 2007 Karma :

panhead · Borekit Bruiser Joined: 30 Aug 2007 Karma :

Damon · World Chat Champion Joined: 24 Aug 2007 Karma :

same here with my RS. no life without full choke on a cold morning.

Thumbs Up

stirlinggaz · World Chat Champion Joined: 22 Jul 2007 Karma :

hi all,
thanks for all the tips.
i suspect its the carb or as Keith says flooding due to needle sticking.
whipped carb out.
full of petrol!
as far as choke goes, i will reconnect it up if i can.
the brass choke cable end is stiil in carb!
need to try & get it out.
would this have anything to do with it flooding?
i forgot it was still in there!
got carb (34mm) in front of me.looks all ok.
cleaned it all.
anyone tell me where to start with idle screw? & mixture screw?
just to re-cap.
got spark.
got fuel,
battery charged up.
kill switch ok,
fuel tap ok.
just been using starter switch.
(never had to use choke before with 28mm carb)
not tried bump starting it, yet.
pissing with rain, will end up on my arse! lol
any other suggestions?
cheers,
GAZ

Uksouth 2013 · L Plate Warrior Joined: 17 Dec 2013 Karma :

Hello I have an aprillia rs 125 extrema and it won't start I have tryed new spark plug and bump starting it incase battery but no luck any ideas ?
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Matt hawton

andy_uk · World Chat Champion Joined: 13 Aug 2011 Karma :

Uksouth 2013 · L Plate Warrior Joined: 17 Dec 2013 Karma :

It has fule and has spark put new spark plug in today but yea the spark plug was wet when took out
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Matt hawton

salem1987 · Scooby Slapper Joined: 10 Sep 2013 Karma :

Ive worked on one which wouldn't run but had all the signs that it should (fuel spark compression)
Turned out it was the petcock tap being dodgey. Took it off and cleaned it and put a new vacuum hose on and it ran perfect.

Or try a compression test if all else fails

Uksouth 2013 · L Plate Warrior Joined: 17 Dec 2013 Karma :

Last time the bike ran there was a sound sing from the engin and when I trying to accelerate around a corner it just cut out and I has no sign of life tested compression and the bike has compression.
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Matt hawton