Alan McLean
Forum Replies Created
-
Posts
-
Hi Max, my GV is 2010, when I got it she was running very poorly so after checking all the electrical side of things I decided to take the carb’s off to clean that’s when I checked the number of turns on the fuel screw so those were the factory settings before I did anything.
I adjusted the needle/slider mode before I changed the main jets, it did cure the problem I had with a flat spot around 5k rpm.
I then decided to go with the larger main jets as per Marcel’s suggestions 90 front 92.5 rear with the same needles, this made the biggest difference, where I live is quite hilly and the bike would struggle but after changing the main jets it was a completely different bike.
I will probably adjust the needles just to tweak it, I still feel there is a bit more to be had from her but happy the way she is performing at present. Just for example I have been away for the last four months and when I came back the bike started on the second push of the button.
I think the next best mod I can do is the 520 chain and sprocket kit from Marcel from all I have read it’s a big improvement over stock, and as I said it’s quite hilly where I live so the 520 kit would certainly help.
Hi Max, not sure what you mean by different carb’s, have they been replaced at some stage?
As regards the fuel mixture screw all I can tell you what mine are set at (factory setting) Front 2 1/4 turns out and rear 2 1/2 turns out. They do recommend that you don’t alter the factory settings on these but if yours has been tampered with you could try the settings above.
Marcel is the best one to ask as regards the main jets, he supplied me with larger main jets front and rear (rear been larger than front) I did not change the pilot jets, my original main jets were 8.25 front and year. The theory behind having a larger main jet on the rear carb is to aid cooling of the rear cylinder, but as I said Marcel is the guru on these matters.
The two screws on the the float bowls is just a drainage screw so should be screwed closed, not too tight.
Alan.
Just to add also, How to remove airbox from GV125 an easier way….
- Loosen bolts for rear intake pipe.
- loosen clamps for intake pipe front and rear.
- Now, remove rear intake pipe”very gentle” and slowly from the bike.
- Measure bolts for intake pipe (eg. M6 x 20 for example, and get stainess steel please)
- Now loosen and slowly remove front intake pipe from under the carb (slide them out nicely)
Step 2…. Loosen airbox bolt from the FRAME (1x bolt holds airbox to frame.) Voila, the carb and air box have come out easy. To fit everything back , do the steps above ^ in reverse. This method protects manifolds and puts them away safely and you can take the airbox with carb together away from bike too next. Caution = If you remove intake pipe , please change “manifold ORING” everytime, as old ones get flat or old after a while and air leaks will happen. Caution = Get big masking tape, and hide engine holes , you don’t want to accidently drop bolts or metal parts inside engine holes and valves will seize when you start. Make sure engine surface is very smooth and clean before fitting manifolds again. Everything else, follow Alan above ^ , i agree with what he has said so far 👍 This link is the slide mod is below
[Tutorial] How to adjust Carb Slide Needle (Tuning) – Hyosung GV & GT 125/250
I will have to try that method myself Marcel the next time I have to remove the carb. 👍
Hi Max, The slider needle adjustment allows the carb’s run a little richer than the factory setup, I did it on my bike prior to changing the two main jets as mine had a flat spot around 5k rpm, it solved that problem for me. It’s probably worth trying as it’s a simple modification and if you’re not happy with the results you can easily return it back to factory settings.
The best way to judge your fueling is ok is by the colour of your spark plugs, so you could check the condition of them prior to doing the mod and then checking them after the mod (clean the spark plugs before riding it again after the mod) once you have ridden it for a while.
Alan.
The most difficult part is removing the airbox, it can be very frustrating but with time and patience it can be done, I have done it a couple of times and it gets easier each time.
First remove the seat and fuel tank (have you removed the tank before?) then unbolt the oil cooler and pull it towards the front wheel no need to disconnect the pipes, remove the air filter and housing and plastics around the air intake, unbolt the bracket on the left-hand side of the bike holding the two coils just let this hang down out of the way, disconnect vacuum pipes etc. from the airbox.
May be a good time to take a break now 😉
Now comes the difficult part, loosen the two clamp’s holding the airbox to the top of the carb’s, there is also a screw on the right side holding the airbox to the frame, remove this, gently pull the airbox up off the carb’s sometimes the wiring loom running running along between the airbox and frame can restrict movement so just pull the loom to one side. When the rubber couplings are clear of the carb’s push the airbox forward towards the front wheel, it will only move a couple of centimetres, now push the airbox to the right side of the bike (I find it easier getting it out this side) it will take a lot of pushing and moving the airbox back and forward to get it out so just be careful not to put too much pressure on the carb’s themselves during this process as this is when the manifolds can be damaged, I found it useful to loosen the clamp’s on the bottom of the carb’s to the manifolds this can give you a little more movement and believe me you need all the space you can get with this job. Hopefully after some time (and probably some bad language 😄) you will have the airbox out.👍
Removing the carb’s themselves is now the easy part, disconnect the throttle cable, choke cable, fuel pipe and vacuum pipes, loosen off the manifold clamp’s fully and gently lift off the carb’s. If I have forgotten anything I apologize but I’m sure you will figure it out.
Good Luck.
p.s Going back on is just reversal of above but I’m afraid no easier 😔
No problem Max, hope it works for you. I do believe Marcel would ship to Germany as I’m in Spain and he has sent items to me 👍
Hi Max and welcome. The float hight should be 7mm (not 17 as per the manual) this is measured with the carb carb body turned up and the float is just resting on the needle valve, measurement is taken from the top of the carb body to the top of the float. As regards the slider sticking just remove it and clean the slider and carb body with carb cleaner or a little WD40, do not use anything abrasive on the slider or the body of the carb, it’s probably just some old fuel residue causing the problem and it’s just as well to clean both while you are at it. As you will be removing the sliders it would be a good opportunity to do the slider needle adjustment, if you type “tutorials” into the search bar there is a tutorial there to show how it’s do, it’s a simple job but worth doing. As regards the springs I would leave them as standard. Removing the carb screw’s is always an issue (poor quality soft material) first make sure you are using a driver with the correct size JIS tip, if that fails a small vice grips usually does it, I would then strongly advice going to the “shop” on this site and ordering a full set of s/s carb screws from Marcel and you will never have the problem again.
Hope this helps, Alan.
Very valid points Marcel regarding the 250 airbox and filter, I will pull the plugs when I get a chance and send a pic of both front and rear.👍
Yes the fuel pump run’s on vacuum, you need to check all the vacuum lines for cracks/splits and especially the inlet manifolds for the same.
Hi Craig, It doesn’t sound like a main jet problem to me as that would normally be a gradual process. If you have spark and fuel going to the carb’s I would be checking for a vacuum leak.
Hi Daniel, great looking bike. Can I ask you about the front and rear mudguards, did you modify them yourself self or did you purchase them?
Regards, Alan.
That’s great news Tom, well done 👏👏
I also replaced the clip’s on the manifolds as you said the originals are crap, I got the clip’s from Marcel and they worked very well.
Spot on with the airbox once you’ve had to remove it a couple of times as I did it’s not such an ordeal getting it back on.
Enjoy and be safe.👍
Hi Tom, using the original factory settings as a starting point is a good idea, if you feel the need to change the needle settings that is something that can be done with the carb’s in situ, as Marcel said a richer needle setting helps the midrange performance, after a little time the colour of the plugs will give you a good indication as to whether you need to richen the fuel/air mix.
Let us know how you get on.
Hi Tom, when I stripped my carb’s my needle’s also had 5 notches, so maybe they are factory fit, also one of my acorn nuts sheered off, also be careful not to overtighten the new one they are fragile.
Be careful even with the new one, don’t over tighten they are easily snapped off. I’ve done it myself 😔
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 have been there, we where looking at buying a property in San Juan de Torres.
Stick with it Luke you will get it sorted.
In what part of Spain are you? I’m in Orihuela Costa (Alicante region)
