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My 2013 GV125 loses power on any sort of incline.
I have changed the plugs, caps, leads and coils. Oil change. New air filter. 520 sprocket set and chain. 90 & 92.5 main jets. Leovince Silvertail exhaust.
After changing the main jets, the performance dropped even more.
I am only getting 50mph on the flat. On any sort of incline the engine boggs and struggles. I took the air filter out and took it for a run. There was a small improvement.
The plugs are new so difficult to tell the colour but look coffee brown.
I can’t remove the air box so haven’t managed to take off the carb. Run a tank of carb cleaner additive. Went in through the side to change the main jets.
I have noticed that there is some surface cracking on the inlet manifolds.
Any help would be much appreciated.
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Have you tried pulling on the choke when it starts to big down? If it picks up with choke on then it’s a fueling issue.
Yes I have tried that. No difference.
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Then it could be a vacuum leak, check all your lines for fit and condition. I would do this before tackling the inlet manifolds, although cracks may be visible they could be just surface cracks but check all your line’s first.
Have you checked your charging system?
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Then it could be a vacuum leak, check all your lines for fit and condition. I would do this before tackling the inlet manifolds, although cracks may be visible they could be just surface cracks but check all your line’s first. Have you checked your charging system?
I have visually checked all of the pipes and no splits.
Not checked the charging system yet. What should I be looking for?
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Wow that’s a lot of cracking, a simple test is to get a can of carb cleaner and while the engine is running spray some carb cleaner at the intake manifold, if the engine revs rise when you spray the carb cleaner you have a leak.
Simple test on the charging system is to put a volt meter on the battery and check the voltage with everything switched off you should be getting over 12 volts, turn on ignition voltage should drop, start engine you should be getting 14 volts at idle, rev to 5k rpm you should be getting between 14.5 and 15 volts.
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Wow that’s a lot of cracking, a simple test is to get a can of carb cleaner and while the engine is running spray some carb cleaner at the intake manifold, if the engine revs rise when you spray the carb cleaner you have a leak. Simple test on the charging system is to put a volt meter on the battery and check the voltage with everything switched off you should be getting over 12 volts, turn on ignition voltage should drop, start engine you should be getting 14 volts at idle, rev to 5k rpm you should be getting between 14.5 and 15 volts.
The battery is 12.2v turned off.
14.2v at idle.
14.6v at 5k revs.
Sprayed carb cleaner on the manifolds with no increase in revs.
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You said it starts and idles and low end power is good! Idle and low end is on the pilot jet as you open the throttle the main jet’s come into play, have you checked the operation of the needle slider, is it sliding smoothly and not sticking?
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You said it starts and idles and low end power is good! Idle and low end is on the pilot jet as you open the throttle the main jet’s come into play, have you checked the operation of the needle slider, is it sliding smoothly and not sticking?
I am kind of new to bikes. Where is the needle slider located?
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Located on the right hand side of the carb, first picture shows the carb’s with one cover removed, second picture is of the needle slider removed from carb the is also a spring under each cover (not shown) the needle slides up and down in the main jet, the needle is tapered so as it rises it allows more fuel to enter. Check to make it slides freely without sticking also check the diaphragm (black rubber part on top of the slider picture one) for damage split’s etc. This can all be done with the carb’s in situ.
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Checked the needle sliders. Removed and cleaned.Diaphrams are both good.
I followed the mod tutorial and moved the cir-clips down one notch. The rear was on 3 and the front was on 4. I moved them so they are both on 4. As stated, both should be the same.
One question I have is, the tutorial says if you have a standard air filter, cut the scorkel. Whats the snorkel?
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Update. Needle sliders are moving freely. Just come back from a test ride. Unfortunately no change. Again rides slightly better without the air filter but still bogging badly. Any more suggestions please?
How fast do revs climb up?
The GV doesnt need a snorkel cutting , that applied to the GT bikes due to their more restrictive filter.
By any chance can you upload pics of your spark plugs? We can see if the mixture is too rich or lean.
Have you been spraying carb cleaner near the manifolds, airbox openings, and airbox mounts (on the carb openings) to see for change of revs?
// Meditation doesn't mean you have to sit still....
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Update. Needle sliders are moving freely. Just come back from a test ride. Unfortunately no change. Again rides slightly better without the air filter but still bogging badly. Any more suggestions please?
How fast do revs climb up? The GV doesnt need a snorkel cutting , that applied to the GT bikes due to their more restrictive filter. By any chance can you upload pics of your spark plugs? We can see if the mixture is too rich or lean. Have you been spraying carb cleaner near the manifolds, airbox openings, and airbox mounts (on the carb openings) to see for change of revs?
Hi Marcel
Out of gear the revs will redline. Pulling away it will rev high. Getting up into 4th & 5th it will only rev to 7k then starts bogging. Any incline and it will only rev to 6k when I drop it down still only 6k.
Sprayed carb cleaner everywhere and no change in revs.
I managed to get the airbox and carb off yesterday with the aid of a fellow biker. Took off the inlet manifolds ( the front one didn’t have split washers and was a bit loose) even though the manifolds have some surface cracking, the inside was sound. Checked all of the pipes and are all good. Put it all back together and there is a slight improvement but not where it should be. Still bogging.
The plugs are sooty
Runs better without the air filter so not enough air getting in.
The chrome air filter cover vent is blocked whilst the cover on the other side is open
Seems wrong to me as no air can get to the filter.
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Hi Luke, have you checked the operation of the choke could it be it’s stuck in the on position! when I got my bike the choke seemed to have no effect when I pulled it on, when I checked it out the choke cable going to the carb was not operating correctly, just a thought as yours is obviously running too rich. Also when you had the carb’s off did you check the float levels?
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Hi Luke, have you checked the operation of the choke could it be it’s stuck in the on position! when I got my bike the choke seemed to have no effect when I pulled it on, when I checked it out the choke cable going to the carb was not operating correctly, just a thought as yours is obviously running too rich. Also when you had the carb’s off did you check the float levels?
The choke is working fine and not sticking. I didn’t check the float bowls. Can I check them by going in from the side or do I have to take the carb off again?
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Sorry Luke you will have to take them off again 😔 You have to turn the carb’s so that the float’s are pointing upwards and the float is just resting on the needle valve, measure the height from the top edge of the body to the top float, the measurement should be 7mm.
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The air filter box sucks air in backwards. The vent at the front was shut to stop incoming rain water going straight to the filter which is a big No No.
The coils have vents to help cool them. The stock coils do warm up a little bit. But mainly the casings are just decoration / hiding things from weather elements.
The GV250 carby has the same capacity. And filter. So dont worry too.much that the box size isnt big enough for a 125. The air filter itself may be showing signs of needing a replacement.
The plugs look tired. Either they need replacing or the mixture screws of the carb wasnt messed with (?) Or wrong size Pilots (?) Or go with Alans latest reply in regards to floats and choke system.
// Meditation doesn't mean you have to sit still....
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The plugs and air filter have only done 300 miles max. Not changed the pilot jets and the rubber plugs over the mixture screws are still in place and have no marks suggesting they have been removed. Choke is working fine.
I will take the carb off at the weekend and check the float bowls. If that doesn’t work I will give up on the bike and get another one. I’ve found another GV in Granada, only 4000km in the clock for 1400€. As soon as I can travel between Spanish provinces I will look at it. Ive got no more hair left to pull out on this bike.
Do you have an air pipe diagram so I can make sure all of the pipes are connected properly?
Thanks for all of your help.
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Stick with it Luke you will get it sorted. In what part of Spain are you? I’m in Orihuela Costa (Alicante region)
I am in Huercal Overa, Almeria Province.
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I have finally found the time to strip and rebuild the carbs. Carb rebuild kit installed. Float height 7mm. Everything looks good.
I have got an “Updated & Braided Air/Vacuum Intake Line Hose Kit” from Marcel. Only problem is the photos on the website are unclear as to where the new lines go. I have only got one connection to the fuel tap, the photos show two. I am guessing the other one is the fuel tank vacuum? Does one go to the two inlet manifolds?
Help would be greatly appreciated
Luke
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Sorry Luke you will have to take them off again
You have to turn the carb’s so that the float’s are pointing upwards and the float is just resting on the needle valve, measure the height from the top edge of the body to the top float, the measurement should be 7mm.I have just checked the GV125 Service Manual. It says the float height should be 17mm. It’s currently at 7mm. Is this correct?
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I have finally found the time to strip and rebuild the carbs. Carb rebuild kit installed. Float height 7mm. Everything looks good. I have got an “Updated & Braided Air/Vacuum Intake Line Hose Kit” from Marcel. Only problem is the photos on the website are unclear as to where the new lines go. I have only got one connection to the fuel tap, the photos show two. I am guessing the other one is the fuel tank vacuum? Does one go to the two inlet manifolds? Help would be greatly appreciated Luke
Because its a GV125.
Both manifolds join with a T-Piece junction and they feed only the fuel pump.
The tap on GV125 doesnt use vacuum as its manual ON/OFF 🙂
// Meditation doesn't mean you have to sit still....
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Sorry Luke you will have to take them off again
You have to turn the carb’s so that the float’s are pointing upwards and the float is just resting on the needle valve, measure the height from the top edge of the body to the top float, the measurement should be 7mm.I have just checked the GV125 Service Manual. It says the float height should be 17mm. It’s currently at 7mm. Is this correct?
Koreans should be more clear.
17mm = when carb is sitting on bike manifolds.
7mm = upside down on the table. 🙂
// Meditation doesn't mean you have to sit still....
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Update.
Bike is back together. Carb is as clean as a whistle. Plugs are clean.
Starts and idles perfectly. Problem is that it will only rev to 7K in neutral. Has no power to pull away. I left it running for 20 minutes and checked the plugs. Both sparking well but they are both as black as soot.
Any ideas?
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Hi Luke, when you had the carb’s off did you check the operation of the float needle valve i.e was it sealing properly when in the closed position.
I think I have found the problem. The bit that the needle sits in on the front carb wasn’t fully seated. It was proud by 2-3mm. Reseated it and tightened the acorn nut. Unfortunately I overtightened it and it snapped. Got a new one coming. I’ll keep you posted when it arrives and I have rebuilt it.
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GV125 Aquila
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