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Dec 11, 2018 at 6:04 PM in reply to: [How to Tutorial] How to Swap Upgrade Carb Main Jets Hyosung GT GT125R GV250 GV125 GT250R #2052
So had another quick look at the bike, I took the air filter off so I could access the carb. I thought I would start it up just to see what it was like and in my opinion it ran better!? I also noticed some black bungs at the bottom of the carb, so removed them to reveal screw heads. What are these for? Also choke is working better with air filter removed. Do I have a mixture problem here? Any help would be appreciated
Shane
Bungs hiding gold screws = Air / Fuel Mixture = Only the factory tunes that. Dealers are told not to touch it whatsoever , otherwise re-tuning is a serious abyss here. I agree with the koreans.
If it runs better without a filter = Investigate air filter (clogged?) or spark plugs (glaze brown means they are healthy)
Glaze brown plugs also mean = carb / filter / electrics are doing well.
To increase mixture = Either add 1 step up from a factory main jet (90/92.5)
Pilots remain size 15 each but must be clean = smooth rolling idle is dependent on pilot jets
Again, investigate your black CV sliders on the carb
Idle and revving up to 7k rpm etc = they slide up
Dropping revs to idle = they slide downParticles on the slider will grind against the carb walls = certain rpms will be bouncy, certain rpms will be jerky –> carb sliders may be hanging
Cleaning them fixes this.
If the sliders are “retracting” fast & (as quick as your throttle moves) – they should be working on
This clip will hint , why its critical the sliders work nicely … (idle , through gears , warming up)
The real key to a free flowing bike is to attack these at once:
Coils , Spark Plugs , Clogged Jets , slow retracting black tube sliders, good fuel pump working , air filter is new (PAPER FILTERS LAST 2-3K before they start to give you less air for carbs)
5k would be pushing it.If its a fabric / cotton gauze filter – it generally is okay until approx 7-10k , the filter will hint how dirty it is.
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“UNLESS” – Someone in the past ever messed up the mixture screws (which were hidden behind black bungs) , then it can explain cause not mixing air intake & petrol properly inside. Like i said, it would be an abyss to retune it back as Koreans never revealed the adjust settings, they do that before shipping the bike away. Depends on country & market its going to.
So the home owner, may go through few spark plugs until its right (plug chopping business)
But honestly, the spark plug colors will tell you how rich or lean the bike is.
Dec 10, 2018 at 5:12 PM in reply to: [How to Tutorial] How to Swap Upgrade Carb Main Jets Hyosung GT GT125R GV250 GV125 GT250R #2045Took the bike for a test ride but it feels like it’s not fueling correctly. As it splutters them revs back up as it should. I had to replace the fuel line as original lines where perishing, but the fuel line is a little to sma I think. Any ideas to what’s wrong. Everything was free and moving as it should on the carb before putting back on to the bike.
Cheers shane– Pilots = affect idle and slow moving , so pilot jets should be clean
– Spark Plug – Clean it , with that carb cleaner – it should spark better, if not IX or Lasers will wake it up better (& bog less under some load) – Stock plugs are just that woeful.
– Fuel lines – Ofcourse, adding thicker high temp lines only add to “more fuel in the pipes = bigger hole” & “fuel is colder = less misting on hot temps, comes to carb as liquid than a misty hot gas)
– Main Jets hopefully should be cleaned up too.
– The “BLACK CV SLIDERS” are critical , they are the mother of the carbs , so you want to make sure they “retract” up & down fast without any delays – that means there is no particles stopping the Sliders moving when you add revs to the bikeWhen you rev , they slide up – they must not delay whatsoever.
Hope this info helps!
Hi I was looking at exhausts. However contacted backwidow and they direct me to the fuel injection type exhaust however mine is an 09 carb model. I am struggling to find a new exhaust for mine and mine is dead it’s been welded however badly corroded and needs new system. Have a new silencer on it max torque can.
Hey!,
I wouldn’t panic – “All years” of Carb & EFI vTwins of GT250R & 125R use the same pipes. Same fitting too.BlackWidows makes the pipes for Carb & EFI , yes correct , but they will send you a “blanking” bolt. Call them and ask them to make sure a blanking bolt is included.
Refer to the image below:

Having said, this would also be the case with Scorpion or MTC UK exhaust companies – They must send a blanking bolt for carb models , if they send you EFI pipes
If you need a stock/standard pipe system that is in a good nick , please call “Startrights Leeds” & tell them this:
Looking for a standard exhaust system for GT125R , in used condition – Marcel says you have the orange hyosung for stripping (I sent you)
They will discount it for you & post it direct. 👍
Their website -> http://startright.co.uk
Good luck, welcome to the forum!
Also, as the RC is 3.5K
Stock clutch may be ok but probably due soon but if youre looking for a better clutch , this site does EBC UK plates & race springs so get more out them and a good torque boost on hills too guaranteed.
Its at /shop/ section of this site. I know no one at all doing race clutches for 125s except myself , our own local UK dealers only do expensive & woeful china plates. £20 a piece!
Id stick with the trusted EBC brand & Suzuki bits 👍
Ahhhh,
Carbs hence i left it as last haha. There is some discussion about this too on the FB group too.
The service manual actually forbids workshops or dealers from tinkering the air mix screw.
Hyosung never revealed how to mess the air screws simply because it would be the abyss to get it right again!
(Lots of plug chopping & re tuning)
If the carb was lean all he had to do was increase main jet 1 size up.
90 n 92.5 so bike is less lean more rich without messing the air screw.
Stock is 87.5 n 90
Dark brown is good! Should be lighter brown all round , suggests to me that you may need more air (filter upgrade due?)
More fuel = more air to mix 👍.
If you search *carb* at the top ,there is a tutorial on jet swapping which mentions more detail on sizes and why we dont need to change *Pilot Jets*
Just *Main Jets* usually only upgraded thats all.
Sooty exhaust may indicate a weak sparking behavior from magneto/cdi? – or else you need more air or the jets are too big (or air/fuel screw ratio off?)
Your mech owes you to fix the carb since he tinkered with it so it must give us a good result?
A little soot is a ok but caution ofcourse how much soot is there. Too much aint good (hint = bike spits raw fuel on cold warm up)
If the carbs are cleaned thats brilliant but did the mechanic clean the CV sliders (the black tubes) they are the mother of the carbs , defo must be zero signs of particles then they slide & retract nicely
(Slider behavior -> Up n down based on your revs => they release JET needle up n down attached to it)
Usually touching carb sliders. Push up by hand and you will see them retract very fast & same pace , no delay or getting stuck = thats a hint of health there.
So battery works. No dimms. Seems to hold well.👍
Did you strip down the bike plastics? And then look at every nook n cranny near the intake system n carbs to really be sure its leak free.
Whatever bolt is on carb n engine must be *tight* = hot engine can make things flex like rubber boots (like taking a gulp of air) the clamps must be tight so it doesnt leak out even a small hint of air.
Last not least, confirm with yourself that all exhaust bolts are tight. We loose power on a leaky exhaust system too.
So to put in short, we are checking intake system , exhaust system for leaks. Re investigate the carbs , jets , air filter and including the black CV sliders in carb bounce nicely (critical)
Keep us updated , we can do all we can to help the bike 👍
Good luck 🔧
Hey dude
The CDI cheat never works on a 125 – whoever said so is a faker
“A few” 250 cdis allow 1 wire to be cut – which helps the 250 engines rev slightly better on its STOCK coils.If you had upgraded the electrics on the bike, it should be very spirited by now.
Sadly, as i’ve experienced fixing customer RC bikes the 4-7K rpm issues is usually caused by either of these:
- Ignition coil isn’t getting 100% electric juice (suspect = cdi / magneto )
- Spark Plug could be sooty (trust me! – RC bikes do not tolerate sooty plugs more than the old gen bikes & electrical changes = RC bikes have some woeful EFI electrics but i digress!)
So –> Sooty plug = Intake issues / weak sparking ? / fouled plug (annoyed plug) - Air filter needs attention = more air is sucked in as you go faster but the carb likes a clean filter & not restricted to less air flow than before
- Clutch needs looking at (any RC over 4K must have a new clutch set as the cheap organics wear down fast –> hence the gearbox drama and false N’s)
Search “Clutch” at the top of the site which explains what kind of power issues you get on a clutch that has worn down a bit (Symptons) - However , we can’t rule out a weak spark or a misfire – Make sure the “HT” cap is under 7k ohms – > RC have an EFI HT CAP for the spark plug that is not that much better than 2007 however too much ohms –> weak sparking -> delayed RPMS
- Intake Manifolds need investigation – > you need to take out the fairings and possibly the carbs off – then inspect your intake manifolds – there should be zero holes or zero leaks (protects piston rings from dirty particles being sucked in too)
- Battery – If it isn’t 12.8v fully charged when off = inspect magneto , all electric juice starts from there before it feeds the rest of the bike too.
If you also switch full beam –> engine off -> indicators / hazards on –> if the dash “DIMMS” -> check battery is holding up juice / not dropping volts too quickly (battery should not discharge quickly) - intake lines (vacuum) – only lose clamps can cause leaks or a very old “stock” line that is rotting inside Vacuum performance is needed for the fuel pump & fuel tap to be effecient in high revs (4-11k rpm) (more demand = more fuel). Big lines help the vacuum & fuel system to run a bit better (colder air/colder fuel) on a hot engine.
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CARBS!
i saved this for last as it’s usually a time consuming process but you may need to inspect your “black CV Sliders” inside the carb and clean them
CV sliders control most of the carb work, so as you rev the bike , the sliders go up , they release more fuel!If the bike is hanging at certain rpms or stuck at certain points –> CV Sliders in the carb need cleaning (common) , Clogged jets in the carb , float bowls need inspection to make sure they are all at the same height (not bent floats)
When you look at your own spark plugs , thats when you get a true story of whats happening to the bike. A healthy motor = all coffee brown color , no black anywhere.
Spark plug color hints = (Intake system / Fuel System / Sparking Electric system conditions)
So it’s a case of verifying what i said above & most times some TLC on the intake system & carbs wakes it up. Electrics are common on RC but not impossible to fix, if you have upgraded electrics , that’s a good thing Less drama down the road!
Let us know how you get on, or if i missed something too.👍
Also have a look at this , as some of my replies can apply to your situation too.
https://hyoriders.club/forums/topic/gt125r-no-power-between-4k-8k-revs/A stock filter has a cone inside and the material is different = restricted.
Also it’s a bit smaller than K&N –K&N can push 3x more air = cotton filter in oil coating – so cleaner bike & more free revving yes. “650 specific” K&N is good otherwise , BMC Italy does it too (known for race filters on aprillias) – I owned some BMCs in some of my bikes , some K&Ns – they do the justice
However – an upjet is mandatory (hence carb tutorial on the forum goes in better detail on jet swapping – just search “carb” at the top of site.
Running 3x more air on the same stock jets = engine is much hotter , misfires , new piston rings soon lol.
Likewise, if you have a performance exhaust pipe –> more gases going out –> upjet is mandatory
Any air upgrades basically (intake or exhaust) = upjet
I live in Surrey not too far from Box Hill, Newlands Corner or the Ace Cafe. Anyone near with a GV Aquila 650 it would be nice to meet up to compare bikes, mine seems to have clunky gear change but is it normal or a problem that needs adjusting.
Welcome!
In 2019, our meets will be near the south UK – You get a chance to meet the lot of us that spawned from the facebook group lol. I have seen a few 650s up north, but not sure how common they are on your southern region – so will have to do a nice map one day!It would be a good idea to head to “Technical Help” section of this site and get a 650 service manual that matches the YEAR of your bike (but most are the same anyway!)
It contains instruction on the best way to “adjust” the clutch cable so that when you “squeeze” it it doesn’t feel clunky to shift up.
It is common that some various hyosung models (125 / 250 650 ) have a clunky gearbox usually caused by either:
– Cable loose or too much play somewhere on the line set up
– Thrust bearing on the clutch basket (if it’s very old & never changed before)
– Bad oil or oil too worn down (cheap oil) (especially when the oil has “worn” down badly, it looses the smooth transition effect on bike) – Manuals generally stress to use premium oils anyway.
– Clutch Springs maybe too old (eventually, hot heat will cause the old springs to fatigue)
(hence its obvious when a gear change isn’t as “snappy” like it was first new)But hopefully it’s just a cable and the adjusters that need sorting that’s all. 👍
Oh yes, it is common!
Nov 25, 2018 at 4:28 PM in reply to: [How to Tutorial] How to Swap Upgrade Carb Main Jets Hyosung GT GT125R GV250 GV125 GT250R #1932Hi Guys I’m looking to upgrade my main jets and do a carb rebuild at the same time. My GV125 had been stood around for sometime before i bought it, in saying that i got lucky getting it going but i know it needs attention very soon. I’m looking for the correct jet size and a rebuild kit for the carb’s. As well as this I’m after some tutorial on how best to remove the carb’s as it was a nightmare the last time i done this and don’t want to struggle unnecessarily. Its fitted with straight through ss exhaust also, thanks in advance Shane
Hey,
If your local dealer doesn’t have genuine Mikuni jets / EBC ones , you may send me a message as I for sure keep a stock of older genuine (on ebay) & some new jets.
I usually send jets with air filters on some custom orders.I have dealt with the GV bikes a few times, one thing is for sure:
– Pilot Jets do not need upgrading at all.
– Stock main jets are identical (87.5 front / 87.5 rear)So a good upgrade commonly is the “90 Main Jet (Front)” and “92.5” (Rear)
Ofcourse the rear is bigger as its the hottest engine, so a bit extra fuel at the back has a cooling effect & slight torque boost in 5th gear.If you head to Halfords or EuroCarParts – My fav cleaner for carbs is WYNNS FUEL SYSTEM CLEANER – It’s a green can , ofcourse any good carb cleaner will blast every hole clean.
Also , i must stress a little here – The “STARTER JET” (which can’t be removed) has a very very tiny hole , ensure you have a good carb cleaner.
After the STARTER JET (that big metal tube that you can’t remove) is cleaned up, your bike will start a LOT faster.
Starting / Cranking = Starter JET
Slow Ride / Idle = Pilot Jet/Main Jet
Normal / fast Riding = Main jet.1 more thing. Head over to poundland & get 3 cans of AIR DUSTER – When the jets are dry , use the air duster to blow the holes clean.
Use the air duster to blow everything inside the carb, after it has dried up from a carb cleaner liquid.
A full clean will really do wonders to the bike. Good luck!
Nov 20, 2018 at 1:59 PM in reply to: [How to Tutorial] Change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram) #1925so it just simple as getting a bolt to push into the tube and clamp it
You got it! That’s it.
Nov 20, 2018 at 11:26 AM in reply to: [How to Tutorial] Change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram) #1923-
also I just found mine as a fake egr but can I leave it installed as it is or does it after be blocked just if it doesn’t make a difference I was thinking of just leaving pipes connected to it saves me the hassle getting stuff to block the pipe etc
These links may help.
https://m.facebook.com/groups/345623961212?view=permalink&id=10154901704736213
https://m.facebook.com/groups/345623961212?view=permalink&id=10154883738251213
That device is for euro tree huggers. Very early GT/GV bikes didnt have them.
Put simply. Bin it = bike is a *little* more throaty and gets rid of pops.
Very common mod on 650s. The forum has an EGR removal toturial for 650 but principal is the same on 125s.
It is as useless as the sidestand switch 😉
Nov 20, 2018 at 9:11 AM in reply to: [How to Tutorial] Change Vacuum Lines on Hyosung GT125R GT250R & GT Comet (Air Hose Diagram) #1920I’m guessing the centre pipe as a splitter before the t junction
Just repeating what was on the 2D diagram but in another way to explain it 👍
INTAKE MANIFOLDS. (VACUUM ROUTING)
=REAR HOLE 1 = Fuel Tap (small port under tank)
=REAR HOLE 2 — JOINS WITH —- FRONT HOLE.
(In other words = Rear #2 & Front Hole are joined with a T PIECE junction.)
Front intake boot always has 1 hole.
The back has 2.
The vacuum pump wants both 1 rear and 1 front to work properly.
Tank Tap goes up un 2nd extra free hole given by the rear.
Uprated Japanese 520 Chain & Sprocket Kit wont this mean chain wont last long on the adjuster
A proper Jap 520 kit will beat any expensive 428. You won’t need to touch the adjuster every day like a stretched 428!. Just keep the chain nice & clean!
IF you go on the facebook group, type in “chain” or something. You will see endless complaints of SNAPPED 428 chains (mind you our bikes are heavy too).
520 sprockets will outlive any 428 sprocket & is wayyyyy harder wearing👍.
EBC “Heavy-Duty” Clutch Plates Friction Drive Overhaul Kit – Hyosung GT125R GV125 GT125 XRX125 RT125D GA125 do they have Kevlar or are they stock
The product page describes the brand it comes from, generally kevlar is good! – The stock ones are just cheaply made (and MORE expensive from any dealer)
This site will never do stock gt125 clutch plates. They are that woeful lol. EBC & Lucas win!👍
Nov 18, 2018 at 4:50 PM in reply to: [How to Tutorial] How to Swap Upgrade Carb Main Jets Hyosung GT GT125R GV250 GV125 GT250R #1887im guessing doing upjet is if you having a new exhaust upgrade or air filter performance
Stock machine = Upjet it anyway (the rear is a little cooler as fuel has a cooling effect) & should run a little better in 5th.
Modded machine -> K&N Air Filter or Stainless Exhaust pipe or End CAN = upjetting mandatory ofcourse. Modded bike ? = Baffle runs better with baffle in than without baffle on any 4T (& quieter anyway! 😉 )
Laser or IX plugs help a lot. If the plugs are “coffee brown” the bike is happy!
The stock ones are too sooty & a nightmare for UK winters, usually chuck em first thing lol.
I usually get a lot of feedback on messenger by the owners themselves, will try to get them to leave more feedback on the shop pages!
However, there are some reviews to be found on the facebook group we run:
https://www.facebook.com/groups/345623961212/search/?query=fuel%20filterThe benefits should have been mentioned on the shop page , but dare i say it, tiny holes don’t help on long trips, these twins definitely like their fuel coming faster through a bigger hole.
A big filter lasts about 15-20K , a stock one is useless after pretty much 5000 ish & a big filter is a big little reserve fuel 😉
if the bike is modded = then stock parts have to go ofcourse. As the usual saying goes “More In / more out” (air & fuel)
Beautiful bike man, looks really sunny out there . It’s winter , we UK folks need our summer back lol
Will try to share this on instagram when i get the chance. I like the cruisers , been thinking of getting one now.
Welcome to the site! Don’t forget to also join the facebook group. I may be doing a competition soon probably but will try get some more member numbers up!
Nov 15, 2018 at 9:02 PM in reply to: [How to Tutorial] How to Swap Upgrade Carb Main Jets Hyosung GT GT125R GV250 GV125 GT250R #1875hello
Very good information over here!
I have a question.. how many turns, after all this mods, do you have at the pilot/air screws??
big thanks
Good question, but according to the manuals (which i agree with), is that the C/O (air fuel mix screws are usually pre-tuned at factory and must never be touch, hence they hide the gold screws with a rubber bung.
The reason for that is also the front and rear engine don’t spark at the sametime, jetting is lager on one carb , then front etc.. so “usually” with these carbs on a 125-250cc type of bike would be about 2.75 – 3.5 turns out – more or less depending on jetting on carb too.
The biggest hint = plugs will be coffee brown , that means stop there & the bike is all set.
However, most mechs don’t always know this and i can’t be surprised when ignore the service manual warnings haha.
Anyways, to put it short. The stock carbs don’t need that kind of tune. Only thing to do is uprate the jets (more fuel) = then add more air (better air filter) then its a happier bike.
“Pilot Jets” don’t need replacing as they as good as they get on the 125 twins, only “extreme” tuning would require air fuel tuning or pilot jet swapping.
Only Main Jets is what most of us all do with a K&N Filter – for a “plug n play” simple weekend!
Hey ,
Welcome to the forum. Someone asked a similar question on facebook not too long ago, so this is what i said (which therein applies to you too)
Here it is:
“”bogging” / Cuts At Stops / Spark Cap being damp ? / not above 40
1. Start the bike – Use a multi meter -> Switch to Volts -> At the battery get a reading of 14v around 3-4k revs
14.2v at idle (if its any less, it won’t have high speed juice.)
Looking at the data says these bikes should be 14 – 15v norminal.2. Switch off the engine , put all the lights on inc high beam. Switch on the left or right indicator – If the dash dims badly – > Investigate battery.
A Garage will just check it for you (they will tell you if it DOES need replacing due to age)
Some Old batteries run worse in the freezing cold.
An Oximizer helps in some cases to pro-long the life an old battery3. COILS = Get that meter out again , switch to K ohms
– > Bike look -> Look for wire going to coils.
-> Put “RED” wire of the test meter on the “spade” terminal of the coil
-> Put “black wire on the BOLT that is attached to the coil”
Get 5K ohms reading (Within that figure)4. COILS = Remove them, scrap the frame off rust, until you see a shiny element – reconnect coils – Spray “tiny” drop of ACF50 (Anti Rust) in to the exposed elements of the coil (frame, fins, wire)
5. Coils = One tiny drop of acf50 inside the “insulator” cap shround helps maintain electrical connection to the plugs , god forbid should water get there.
6. Spark Plugs = Dark Coffee cream colour = Jetting is OK. (not rich)
Must be almost identical to both engines.If there isn’t ACF50 to use or similar product – Clean the areas of rust near the coils & bike harness (wires) especially when they attach themselves to the frame
7. Spark Plugs = Take em out, clean the tips –
The only plugs i can verify & few others is that now “CR8E IA” lasers plugs do better job at maintaining throttle response (its easier for the engine to burn off fuel in chambers)
“IX” is good too, but IMO waste of cash now as it’s not as dramatic as switching to IA ones.YOU WILL be less likely to use the choke!
8. Can get to 40 plus?
– Valve Issues (Tappets/Cam Chain/Tensioner/Valve Springs) – Believe it not, you won’t ever see 70 plus if the valves system hasn’t been service – Get the service history & find out when it was done compared to your current mileage now. A clear running video helps , if you ever post it.
– Carburetors (will explain below) – Bike can’t run good without it 100% right.
– Coils (^ as above ^ ^ ^ )9. Air Leaks = Investigate these areas:
Airbox (unsecured air filter?) / Carbs (check rubber manifolds are tight) / All hoses.10. Boggyness = Too much fuel or weak electrics.
Other hand, if it runs better on choke (enriching) – Sort the jets.
Choke for 5mins is enough. They get hot quick if they stay above 3K revs.High revs = Too much or leaking somewhere.
Boggy low revs = Electrics or Fueling system. / Weather.Set idle speed to 1650 rpm when its normal (running fine)
Next time it starts from cold, it will idle a bit higher than 1300 rpm which for some reason is way too weak , fine on bigger cc machines. A CBR 125 2018 idles at 1700 from cold. We have 2 pistons to spin.11. Carbs = This whole operations means carbs stay on the bike & you’re on the left side.
Drain the fuel (1 screw INSIDE each bowl) (x2)
Fuel drains on the small lines. Get a bowl.
Take off the bowls.
Inspect your carbs.
You will see 4x jets (2x main =above20mph they take over)(2x Pilot Jets.)
Stock sizes 87.5 at the front + 15 Pilot then 90 Rear (+15 Pilot)If unsure, remove the carbs entirely and have a local mech blast it clean. in & out.
12. Cuts Off = Sidestand switch &/Or – Fuel delivery issues (inspect whole fuel system from the tank to the carb)
Sometimes your bike electrics may be fine , but the carbs may not be cooperating…. A lot can be done these motors run better but let’s get them to standard running 1st (y)
Kill the list ^ one by one
If you ignore all i said ^ and are in a rush – Kill the rust, check contacts , hear for sounds near the top end ; touch the clutch basket to feel for any low-end knocking , or loud basket clatter (clutch plates) , ensure the bike is dry
Failing that – Time to inspect in detail ^A naked comet much easier to get to that a GTR. As with naked bikes, inspect their exposed elements (y)
All GV125/250 engines have “shroud” cover that is supposed to seal the entire spark plug hole (old age can detoriate them , so check) its separate – You can actually take it off.
Listen to both cylinders and inspect their heat consumption during warm up – If the rear is cold – the coil is dead or there is no juice going to plug or its too fouled , etc..
A bike running 1 one cyl must feel like its taking twice the time to take off at lights & WILL stuggle on hill climbs above 40.”
—————————-
End of quote.So take some time, i think you may laugh later, could just something silly that has gone amiss while you are busy investigating it.
Since it is a new bike, it should be under warranty, the dealer has a responsibility to make sure it is at optimal running. Also it is less than 1,000 miles old, so you could give it more chance to “run it in” (engine wise) so that after 600 miles, a full major service can be carried out , this includes valve clearances , timings check (these can affect top end power) , flushing the oil with fresh one , checking the whole bike basically. If something was amiss, they must replace it or supply you the part free as under warranty.
Hope this info helps, but update us all on your progress!
* Any * pipe on bike = must be replaced within 2-4yrs max.
Rubber rots inside too. And gums up parts. Stock lines have tiny holes (slower flow)Braided fuel and air lines last 10 years , and they run colder (meaning heat resistant) so your fuel doesnt turn gassy on a hot day.
Big holes flow more air and fuel. So your carbs get fuel quicker , big vacuum lines help your pump flow fuel better (it works like a pulse)
So more air in the vacuum system helps.
Giant filters (a good one!) Hold more clean fuel as a mini reserve plus your carb has less dirt going to it. Cant trust every Petrol station out there.
So yes air and fuel lines help. Any extra info is at /shop/ page or search *fuel* in the search bar ^ for a diagram . Pictures will reveal the differences.
Next up. Stock jets are crap. I’ll leave it at that lol.
Bigger jets = slight torque boost, rear engine is COLDER since petrolium has cooling effect.To understand or how to swap carb jetting Search *Carb* ^
There is a lot that can be done on these machines, but one warning. They hate *china* copy parts! Eg. Cheap £1 lines. 😉
For anything else (tune wise), copy this link or tap below
https://m.facebook.com/groups/345623961212?view=permalink&id=10154079865506213It saves me rewritting as i get asked often but i am amending the list above as i have done a lot more since then.
Will be finding time to make a proper 101 Book for all things GT125R tuning with probably 3 pages but should be enough to allow people to do things without paying mechanics robbery prices.
Also i have uploaded as many service manuals in forum as (125/250 = same frame) so books also contain a lot of maintenance info etc…
Ofcourse, if try everything I said in the previous replies , your bike WILL run better!
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