Suzuki GN125 Rough Running

[Lhavau]

I've just bought my wife a GN125, R plate with 10,000 miles on, very cheap, very nice. Only thing it was sat in the previous owners garage since 2004. It starts first time, has a clean plug, i've changed the oil, but it has some problem, which I suspect is the carb is clogged up, as when you rev and let the throttle off, it "sticks" on high revs even though the pull has gone full back to close position, then it hunts and dies. I see there are complete new "taiwan copy" carbs available to buy from Wemoto for £60 inc. post, so question is, do i just junk the old carb and go for this copy, or is the copy likely to be no bottle, do i attempt stripping & cleaning the carb as i've not touched one before, or pay a garage. Are they pretty easy to get out, it looks like it just literally hangs on between the intake rubber and airbox, with just the petrol and throttle connection to remove. Any advise regarding how to remove & clean the carb, or better suggestions, would be appreciated. cheers.

[cammy mack]

if its still revving its nuts off with the throttle closed it sounds like the throttle slide is probably stuck.
take it off, strip and clean it with carb cleaner as it will be full of old congealed petrol.

HTH

[Lhavau]

Thanks for this - i took the carb out, took the top bit off with the spring in, have established that the diaphram looks ok, no splits or damage, pulled it out, the needle looks fine, drowned the barrell in carb cleaner and stuck it back together. Took the bowl end off, there was nothing untoward looking in there, unplugged the jet cover - how are you supposed to get the actual jet out? it doesn't drop out, i can't see it unscrews?? Again drowned it in cleaner, re-assembled and stuck it back on the bike. The bike fired up again eventually and it now does appear improved, but what's happening is that it will tick over at idle fine by itself for a minute or two, then suddenly start going up the revs by itself until you manually rev it, and it will clear, then hunt and either stabilise or die. I tried a quick road test round the block and it still feels not quite there, not happy about the missus riding it with her inexperience it may be daunting if it suddenly sticks on full revs.... any further ideas much appreciated!! Would a new carb be a definite end to the problem, it couldn't be anything else causing this? The intake and airbox rubbers look fine and were tightly clamped, the spark plug is tightly installed and clean.... don't know where else to look.

[Noxious89123]

Put any fresh fuel in it?
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'06 Honda CBR125RW-6 ~ '00 Honda CBR600F-Y ~ '07 Honda CBR600RR-7 ~ Bikeless
'53 Ford Ka 1.3 ~ '03 Vauxhall Astra SRi 1.8 ~ '52 Vauxhall Astra SRi 2.2 ~ '53 Vauxhall Astra GSi

[Lhavau]

Yep, new fuel, old tank was completely drained, added fresh fuel, the tap has a filter built in so fuel blockage shouldn't have been a problem (?), the carb was obviously empty as i took it apart... tried it tonight, it seems to be better when it's first started, it's starting with no choke but doesn't idle cold, the choke is the simplest thing on these, just a lever on the actual carb body, again i drowned the cold jet in cleaner when i took it apart.... guess once i get the chance to give it a few miles on the road it may clear itself?....(hope!)

[Keir]

take it out for a good ride and once warm give it some high revs. you'll be amazed what a thrash can do.
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Current : '08 Yamaha FZ1s
Previous: '99 Honda CBR 600FX, 03 ZX636 B1H, 99 Fazer 600 (red), 02 GSX-R 600 K2, 00 SV650s (red), 2008 ZX10R, 97 Bandit 1200N, 04 ZX6RR K1H, 04 GSX-R 1000, 98 Fazer 600 (gold), 05 Madness 110 Pit bike, 04 CR125R, 00 SV650s (black), 06 KTM 625 SMC, 99 SRAD 600 track bike, 03 SV650, 98 Bandit 1200N, Bandit 600SY, 03 GSX-R 600 K3, 01 GSX-R 600, 01 Fazer 600 (black), VFR 400 NC30 x3, 78 Honda Dream, 00 Speedfight 50

[Lhavau]

Have stripped the carb down twice now, given it about 50 miles today and it still isn't shifting the problem it's running at speed ok, accelerates and slows ok, it just won't clear this thing of either revving it's nuts off at tickover or hunting then dying - i suspect that 5 years in the back of the garage has killed the carb.... so back to my original question - could it be anything other than the carb, ie do i spend £60 and chance it, as presumably i couldn't return it once i've used it. cheers

[Alexio]

When you say it "sticks" at high revs, do you mean that the throttle grip actually stays where it is?

I had a throttle cable that I didn't lubricate and it did this in the winter time, I could accelerate with some force but it would take a while for the throttle to slip back out again so it was doing the maximum revs absolutely all of the time. I learned some GOOD clutch control until I replaced the throttle cable.

Otherwise, if it's not your throttle cable / linkage then who knows.
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will never give up his CG. I look at my fuel gauge more as a progress bar than a fuel gauge.
G: With my GSXR I do often effectively use it as a scooter with a clutch in town.
ms51ves3: why does it need 500 miles? Are you teaching it how to be a piston?

[Lhavau]

Hi - not the throttle grip, or the linkage - i suspect the carb is a w/o, maybe damaged from being started after 5 years.... i'm gonna get another carb to try to fix it.

[paddlesat16]

I think you need to completely disasemble the carb, take the float chamber off etc and unscew the jets and soak in carb cleaner. Place it all on clean kitchen towels on a clean surface. The carb won't be dead after sitting in the back of a garage for 5 years. just probably gunged up with old fuel in the float chamber... soak overnight, clean off and reassemble, if you can blow off parts with compressed air. Oil up the throttle cable and throttle on the bike with clean engine oil.
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I once saw a bloke shagging a donkey.... in Saudi arabia. Theory Test Passed 26/10/09 Mod 1 Passed 26/4/10, Mod 2 Passed 7/6/10 Current Bikes Suzuki GSX1400 K5, Aprillia Pegaso 650, Suzuki DR350T.

[Lhavau]

Have fitted the new carb from Wemoto (ordered on Sunday, arrived on Tuesday!), the brand on it is Kymco, have fitted it, the GN is now running like a totally different bike ie normally!! Thanks for the advice everyone, hopefully now the missus can ride it with peace of mind.

[shanekaettle]

as u already have a new carb this is incase any1 in the future has same problem ias been having the same trouble and worked it out this morning it turned out the past owner had the mix screws wrong way round. i only worked it after i had run out of ideas and then this morning noticed the new needle was bent. more of a look into it i see the mix screw was abit toooo long so i swapped them round and straight away the problem has gone ... hope this helps any 1

[paddlesat16]

stick some reddex in with the fuel, and give a whizz round the block a few times. That should soften up the gunge in the carb and clean it through.
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I once saw a bloke shagging a donkey.... in Saudi arabia. Theory Test Passed 26/10/09 Mod 1 Passed 26/4/10, Mod 2 Passed 7/6/10 Current Bikes Suzuki GSX1400 K5, Aprillia Pegaso 650, Suzuki DR350T.