Cold startup issues – GV125 Carby
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Hi everyone,
I have just bought 2016 hyosung GV125 Classic 2016 , I have done full service, new oil , filters , plugs etc , and what issue I have is basically difficulty to start up when cold , it will take up to 30seconds before it will start , as soon bike is warm it starts straight away, have you got any suggestions what else I could check or adjust?
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Hey Darius. I’m pretty sure it’s the same Darius that did his CBT at Buxton today? It’s Anton, they kept me until 5pm but I got through it ok.
I take it that you and Dimitri (?) were done and dusted before I got back. I have to admit, that was more full on than I expected, I was cabbaged by the time I got home 😂
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Hey Darius. I’m pretty sure it’s the same Darius that did his CBT at Buxton today? It’s Anton, they kept me until 5pm but I got through it ok. I take it that you and Dimitri (?) were done and dusted before I got back. I have to admit, that was more full on than I expected, I was cabbaged by the time I got home 😂
hey Anton , yeah 👍 great spot 🙂 glad you have completed, I have gone for 80miles ride afterwards 😂 could not resist to take my GV in the road ( btw) problem with startup gone , looks like needed a good blast after long storage! Come on man ! Go for it and get one ☝️ -
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Hi everyone, I have just bought 2016 hyosung GV125 Classic 2016 , I have done full service, new oil , filters , plugs etc , and what issue I have is basically difficulty to start up when cold , it will take up to 30seconds before it will start , as soon bike is warm it starts straight away, have you got any suggestions what else I could check or adjust?
Welcome and to your friend on here too lol.
Okay, how about this?
- When was the last time the carb even had an ultrasonic clean? (a very big deal)
- Valve Clearances? (Loose valves make it hard to start cold, heat tends to narrow gaps , hence easier starts, but power will be lacking in general , so either, get some proof the valves were done in the last 4,000 miles as per Korea’s rules, it is a lot of valves for a 125 after all 😬
- What fuel do you use ? E10 , E5 Super ? which stations ?
- Have you ever had the airbox off ? (We have 2x tutorials for that in the tutorial section)
(Bad “o-rings” under the manifolds , make it quite annoying to start , however engine can reach 100c degrees, eventually the orings will cake and need replacing, since it will allow particles and dirt to mess up the air system and the carb since they are upside down sending air down the engine with atomized fuel for plugs to spark properly) - Owner messed with the jetting or carb mixtures?
- Replaced the plugs ? – Be ready to replace them again with another set of normnal CR8E (only that size please) – If the air system or carb system ain’t right, the plugs foul easily
(you’re welcome to post plug colours on here to see how well it is doing)
It’s a lot to ask I know, but don’t rush, i will have a proper answer based on data you gave us. Assumptions could mean false diagnosis (i said this, when it was actually something else etc) , so I want to be as accurate as i can 😉 , considering i fix these bikes all the time.
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Hi everyone, I have just bought 2016 hyosung GV125 Classic 2016 , I have done full service, new oil , filters , plugs etc , and what issue I have is basically difficulty to start up when cold , it will take up to 30seconds before it will start , as soon bike is warm it starts straight away, have you got any suggestions what else I could check or adjust?
Welcome and to your friend on here too lol. Okay, how about this?
- When was the last time the carb even had an ultrasonic clean? (a very big deal)
- Valve Clearances? (Loose valves make it hard to start cold, heat tends to narrow gaps , hence easier starts, but power will be lacking in general , so either, get some proof the valves were done in the last 4,000 miles as per Korea’s rules, it is a lot of valves for a 125 after all 😬
- What fuel do you use ? E10 , E5 Super ? which stations ?
- Have you ever had the airbox off ? (We have 2x tutorials for that in the tutorial section) (Bad “o-rings” under the manifolds , make it quite annoying to start , however engine can reach 100c degrees, eventually the orings will cake and need replacing, since it will allow particles and dirt to mess up the air system and the carb since they are upside down sending air down the engine with atomized fuel for plugs to spark properly)
- Owner messed with the jetting or carb mixtures?
- Replaced the plugs ? – Be ready to replace them again with another set of normnal CR8E (only that size please) – If the air system or carb system ain’t right, the plugs foul easily (you’re welcome to post plug colours on here to see how well it is doing)
It’s a lot to ask I know, but don’t rush, i will have a proper answer based on data you gave us. Assumptions could mean false diagnosis (i said this, when it was actually something else etc) , so I want to be as accurate as i can 😉 , considering i fix these bikes all the time.
hello , thank you for your response,
I must admit I have very little knowledge of what has happened to my bike before I have purchased it , basically old man passed his full license and he kept this on I a garage for 5 years,
If we are talking carbs , and valves I have very little knowledge of how to adjust / clean if necessary ( new to motorcycles world) however there are no lack of power while bike is running, idling approximately steady 1400rpm no issues with revs , acceleration etc , alternator works perfectly fine with 14,3 output, I have fitted new battery, new air filter ( carbs looked clean ) when I looked when filter was removed however I did not inspect -rings ( lack of experience and I will re check again ) im using currently E5 shell petrol , and I have added liqui Moly fuel system cleaner , as bike was not used for a long while , before first start up I have drained old petrol and replaced with new , when I bought this bike plugs inside were CR7HS but I have replaced them back to NGK CR8E spark was strong after installation ( checked before putting them in ) old plugs were black and I’m attaching pictures, bike seemed to run rich at the beginning due to stron petrol smell from exhaust but after replacement it has gone a lot better,
thank you for your recommendation and suggestions it is much appreciated, shame you are far away from Stockport as I probably would pop in to you and let you do full in depth inspection.
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Don’t worry about Stockport, we collect bikes all over but lets save that for last, let see what you can do as your hands are free labour , she might want you first.
i will try not to overwhelm you today, so go for a ride with CR8E plugs, come back and show us the plug colours for front and rear cylinders , then i can fully understand with a trained eye where your “mixture” situation is and if the bike is overheating or not.
In regards to electronics;
- If the reg says 14.3V , that is good. What numbers do you get at idle and what numbers do you get at 5k revs ?
- We will test the stator soon, (it also is responsible for sparking believe it or not, as the CDI reads the stator’s “coil” to tell when plugs shoud fire up etc, if the stator “coil” wanes, you get dark plugs you see but ….speaking of coil….
Sparking Plug Coil test. (Too easy).
- Remove the left side cover hiding the coils.
- Remove HT cap from the spark plugs.
- Turn on your multi meter.
- Switch your meter to 20,000 (thousand) OHMS
- Put the “RED PROBE” inside the HT Cap
- Put the “Black PROBE” on the “engine valve cover bolt” (or any unpainted area of the frame that isn’t rusty)
- ===== Tell us how much ohms you get front and rear.
Part 2 = Try get a picture of the coils and caps. I have a suspicion about it , if the owner put CR7 (totally wrong plugs), he probably put wrong coils which emphasizes your cold starting woes (probably!)
Part 3 = Sparking Coil Test (Primary vs Secondary resistance)
- Keep your “BLACK PROBE” of the meter on the frame
- Disconnect the “Signal Wire” That is SPADE Shape (Front is yellow/black and rear is white/blue)
- Put the RED PROBE on the “Terminal Connector” of the coil itself.
- Reduce the meter down to 10 (Ten) Ohms (As low as you can get)
- Tell us the ohms for each coil. I will asdvise them if they within factory spec as per korea’s service limit rules or replace with upgraded ones
In all cases , I would recommend “NGK” caps you saw at this store & Laser Plugs & Ignition Coils = Now you will literally never have to accuse the sparking electronics for letting you down this winter, plus you can do it yourself without needing a garage. I will provide a tutorial on how to fit caps if need be. Do not ever buy “CR8EIX (Blue Box IX Plugs)” as Hyosung 125’s generally do not like them and they tend to wanne fast after 5k miles. If want NGK’s best plugs for the street use, it would be their Laser type.
NGK Caps rarely fail, too trusted of a japanese brand at this rate.
OEM Coils = Common, we upgrade them all the time to ones that “resist” less, so bike makes use of them right away. Can’t blame Hyosung for it as they didn’t make the coils, just outsourced part with their logo stamped on it that’s all. Much like 90% of owners upgrade the stators and regulators and call it a day.That will finally leave us with the carb and airbox and intake being a special delicate event!
Liqui Moly is good! – Don’t use redex though, if you want to try “prolong” the idea of taking off the airbox and carb cleaning (ie, you need the bike for work during the week i guess) , go to Halfords and get this only
Regardless if you have half tank or full tank, pour the entire bottle in. (Aggressive method perharps? but follow me here…)
Your bike’s mood should improve slightly or more as it drinks down its fuel , the cleaner will collect stuff long the lines, pump, tap, carb unit, and it burns away from exhaust. This is the product i use on all my bikes, usually once every few months (well some pumps at the stations are not all perfect) , good thing we also have fuel filters, so keep an eye on that fuel filter for gunk build up. Remember we want to fix the easy parts of the bike because the “carb & airbox” will be one of the most “patience” testing things you could do but boy you will learn a lot and it will thank you ten fold. (Even if we have to remove them to access the intake manifold orings under the cylinder heads) -
Hello ,
Thank you again for your great help ,
I have started today with 25miles ride and as much bike had easier start today but in exchange I had few times problem during red light stops where bike decided to stall after few seconds of idling😣
on return first I have checked voltage , idle it was showing 13,8 , 2000 rpm 14,2 , 5000rpm 14,7/14,8. , after that I took the plugs out ( pictures attached) looks on lean side which potentially could explain why bike decided to stall on stops , I have took pictures for your inspection of current ignition coils , however I’ll do proper testings tomorrow as it has gone dark and I could not see a thing (baby steps) ,
front cylinder
rear cylinder
I can not explain how grateful I’m with you sharing your knowledge and experience on these bikes.much appreciated
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Well done , you’re getting there. 👍
So i will break down the plugs in simplest terms so you know what to expect (Get a fresh set of CR8E x 4 of them) part of this process is unfortunately called “Plug Chopping” , gotta go through a set of plugs until she is happy, as old plugs wane fast and dont behave the same if they dont work well (“Fouled up”) .
Your plugs:
- “Dark Black Ring” = Rich Idling / Low air / Dodgy mixture (i hope not) / Pilot Jets too big / Ignition Coil + HT Cap (easy fix) / Choke used during startup or while riding etc… (choke enriches the carb)
_________
Ideal colour = English brown tree trunk / Milk Chocolate / Brown Leather Boots = I know, but best way i can describe a ideal shades of brown or “Tanned Grey with Brown Tinge” ==> Means starts should generally be easy in icy days or not even needing a choke.
_________ - “White Pure Center” = Main Jets Blocked / Slide Needle is wrongly put to the lean setting / Air Leak at high revs / Low fuel flow at high revs / Main Jets too smll /
______
Ideal Colour = As above ^ . White is never a good sign because it would mean there is very little fuel at while riding and bike is going to overheat faster , the oil in the bike breaks down hard (sooty black oil much sooner) , plug breaks down , holes in piston may burn one day , compression loss due to piston rings cooking in extra heat, and so on, i believe you will get the gist of where we are going with this. We would rather a dark center than a white one , at least “slightly” rich MAIN JETS or SLIDES means high speeds help the bike cool a tiny bit on each intake cycle , as petrol has a tiny cooling effect (tiny) (Another reason GTR bikes for Hyosungs have bigger jets at rear than the front due to the fact, it gets less air flow to it hiding under the plastics , plus the front engine is in the way , just how v-twins are.)
I hope this made any sense ?
Let us know your test for electronic sparking coils later on, take your time, it’s a stormy week anyways.
- “Dark Black Ring” = Rich Idling / Low air / Dodgy mixture (i hope not) / Pilot Jets too big / Ignition Coil + HT Cap (easy fix) / Choke used during startup or while riding etc… (choke enriches the carb)
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Well done , you’re getting there. 👍 So i will break down the plugs in simplest terms so you know what to expect (Get a fresh set of CR8E x 4 of them) part of this process is unfortunately called “Plug Chopping” , gotta go through a set of plugs until she is happy, as old plugs wane fast and dont behave the same if they dont work well (“Fouled up”) . Your plugs:
- “Dark Black Ring” = Rich Idling / Low air / Dodgy mixture (i hope not) / Pilot Jets too big / Ignition Coil + HT Cap (easy fix) / Choke used during startup or while riding etc… (choke enriches the carb) _________ Ideal colour = English brown tree trunk / Milk Chocolate / Brown Leather Boots = I know, but best way i can describe a ideal shades of brown or “Tanned Grey with Brown Tinge” ==> Means starts should generally be easy in icy days or not even needing a choke. _________
- “White Pure Center” = Main Jets Blocked / Slide Needle is wrongly put to the lean setting / Air Leak at high revs / Low fuel flow at high revs / Main Jets too smll / ______ Ideal Colour = As above ^ . White is never a good sign because it would mean there is very little fuel at while riding and bike is going to overheat faster , the oil in the bike breaks down hard (sooty black oil much sooner) , plug breaks down , holes in piston may burn one day , compression loss due to piston rings cooking in extra heat, and so on, i believe you will get the gist of where we are going with this. We would rather a dark center than a white one , at least “slightly” rich MAIN JETS or SLIDES means high speeds help the bike cool a tiny bit on each intake cycle , as petrol has a tiny cooling effect (tiny) (Another reason GTR bikes for Hyosungs have bigger jets at rear than the front due to the fact, it gets less air flow to it hiding under the plastics , plus the front engine is in the way , just how v-twins are.)
I hope this made any sense ? Let us know your test for electronic sparking coils later on, take your time, it’s a stormy week anyways.
hello again ,
weather looked not to bad today so I have managed to do some measuring for you please see attached photos ,
Front cap ,
rear cap
both coils shown 0.6
hope I did this right ,
thank you again for all of your assistance
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Based on your reply
- Both coils are GOOD, but almost at service limit. Keep them. Saved a bit of money for now there…. Upgrade whenever you feel like it it or if it goes beyond 16.1K with its OEM cap attached.
- Upgrade to NGK caps at your own leisure, that should help even more and your resistance goes down a lot (easier to light up them plugs)
I hope you learned something, you will be your own wizard soon!
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Based on your reply
- Both coils are GOOD, but almost at service limit. Keep them. Saved a bit of money for now there…. Upgrade whenever you feel like it it or if it goes beyond 16.1K with its OEM cap attached.
- Upgrade to NGK caps at your own leisure, that should help even more and your resistance goes down a lot (easier to light up them plugs)
I hope you learned something, you will be your own wizard soon!
Thank you Marcel , definitely great lesson,
So what are next suggestions? I have fitted new plugs , coils are good , caps as well , but still cold start issues, and stalling when hot 😣, I’m kind of hoping you are not going to say carby removal and clean up but something is telling me we are going that way.
thanks again
best regards
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I assume you have read the 2 tutorials on carby removal ?
Unfortunately it looks like we’re headed that way because we can’t be riding on white plugs , it is way too lean to make economical sense to ride it, if something happens , the damage will be worse for your wallet unless you have a backup engine to swap! 😬😬😬
While it is off , it will be a chance to give one full overhaul before the bitter winter sets in. and replace parts , i’d get the parts it needs first so you’re prepared.
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