♠️ M77
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Can you attach pictures of the plugs if you can please ?
Side view ( so we see threads )
Top view ( to see middle colours )Also have you tried a fresh set of CR8E plugs ?
Also , are you able to test your coils for primary and secondary resistance ? (sometimes coil is bad, and HT caps can’t output enough spark power to plugs at high revs)
Also , remove HT caps and measure ohms of HT caps without coils attached to it. (sometimes coil is okay but HT cap is breaking down / stress)
For the Jet needle , have a look at this tutorial to see if it helps
[Tutorial] How to adjust Carb Slide Needle (Tuning) – Hyosung GV & GT 125/250
Hello,
Set the mixture to 2.5 turns each pot. Take out the pilot jets and look in the sky with them, if light does not shine thru the pilot jets. This could be a problem and also a sign that carb needs more aggressive cleaning (Yes , sometimes CV carbs not just hyosung, but may need cleaning 2x) unless it has been in a good ultrasonic bath + air compressor afterwards (there many holes inside the carb)Also check fuel filter for any debris coming from the tank.
The fuel should be E5 (it may be called different in Norway) but here in UK , E10 fuel is generally bad for bikes (nothing great about extra ethanol)
Also when bike is running, spray carb cleaner to carb rubber intake pipes and also rubber holes for airbox, if any revs change, you have air leak. Sometimes changing “manifold orings” under the carb pipes helps a lot.
If you can, wait for bike to be 10 minutes hot, then test compression for cylinders.
1. Take out spark plugs (both of them)
2. Compression tester (a good one!) inside cylinder one (front engine)
3. Twist throttle to full throttle.
4. crank the bike for 10 seconds and look at compression numbers and tell us.
5. Repeat this for rear cylinder.Clearances when bike is overnight ice cold (that means let it cool down overnight, then check in the morning) all intake valves will be 0.12mm-0.15mm optimal (0.10-0.20)
All exhaust clearances will be 0.25mm optimal (ish) but range is 0.20 to 0.30 max.
Did you also set the floats when carb was upside down on the table ? to 7mm ?
I would also caution that if there is any doubts about the “fuel valve” that’s under the float, its okay to replace it with some rebuild kit or even just get new floats.The float area can also cause big issues from starting bike to full throttle if its not behaving well.
Hola Jose, in what part of Spain are living? I live in Orihuela Costa.
I live very close to you, in Murcia city; and more exactly, I grew up beside the old airport of San Javier (I’m sure you know it
)Sounds like a good Spain meet up is due in your country guys, go set it up & keep the hyo scene alive 😉 , i’ve also noticed more Spain members joining this site too. It’s good to see!
I have been using Yuasa on most of my bikes not just Hyosung , i trust them. I’ve had a yuasa last me 3 icy winters (3yrs) and it was also because the charging system was in good spec (Stator = good AC output , Reg = good DC output)
UniBatt & VARTA are also good alternatives because i have used them also.
MotoBatt ,i’ve not tried them either as per simon, (but i don’t have a desire to try them now though)
14-BS is correct and OEM size as per good Simon!
Thanks to Marcel and Simon. After fitting upgraded stator & flywheel, coils and rectifier bike running better than ever uprated sprockets makes a world of difference
.Hello Dave,
I am very happy for you!
If it is not too much trouble for you, check the stator and reg pages on the shop and go to bottom for “review” section and leave some feedback. It lets everyone know how it actually performs from your own point of view , they can’t just take my words for it 🙂Especially with the 520 chain kit (if you got it from us recently) , leave some review to see what changes it did from stock setup , ie. 1st was 20 oem , but uprated was 15mph (faster) or 30mph (slower but each gear range is extended), or balanced etc etc.
Look after her fella 🙂
I don’t have compression test gauges but wouldn’t mind investing in some. Do you know what size/pitch type fits the plugs? The engine won’t rev to full throttle – it dies if I try get to 1/4 throttle. I am curious, how would the comprssion test results aid in determining an issue? Cheers,
Start it up and keep it running (by any means) until its hot for 10 minutes.
Take out both spark plugs, then fit one compression tester probe in to front cylinder, twist full throttle and press start for 5 seconds to get a reading.
Then wait for starter motor to cool down, repeat again on the rear engine.
Make sure battery is fully charged, as slower spinning cranks will give false positives. (unless starter motor itself
Amazon Prime, get one that says USPRO compression testor. Connect the “straight metal” pipe. ignore flexi tubes etc…
Now hold it down to the plug hole hard.
Welcome to the Club Jose!
Be sure to share some pictures of your ride here
There is some good info on the forum and also a 250 EFi service manual on the forum’s technical section, if something is missing you can also make a new technical topic yourself describing any issue you might be having
If you have pictures , it may help to show us the situation too. Double check EFi service manual in this forum for the 250 has the wiring diagram at its final pages, i think it does , it has been a while since i read it!
At 1500 miles, you or your dealer should have this done on record now or sometime sooner when you get the chance
- Oil Change = Motul 7100 (no matter what he says) , premium oil is better than cheap poundland oil (some garages are known to use crap drums of oil in their workshop to save money as they fill it up on various customer bikes
Or Silkolene Pro 4 or Comp 4
At 10w40 grade only (forever this grade) - Fresh oil filter = Always with every oil change.
Hyosung suggests to change oil every 4,000 km. This is England with 125cc bike commonly used frequently (wether pleasure or work related) with them living higher rpm lives most cases , I in my opinion think 1500-2000 is a good interval to change oil & filter. - Adjust Valve Clearance (this should be on record at 600 mile run in aswell, if in doubt, it’s advisable a garage does this)
- Clutch = If nothing is slipping by now, assume the bike has been run in properly at its first 600 mile life, we don’t need to worry about this unless going heavy duty upgrade.
- 2023 = Change anti-freeze (mileage doesn’t matter).
It is 2 years from the date it started running. (not registration date plate date) - Check bodywork for any signs of loose bolts.
- Brakes (pads wear down eventually)
- Rust on “slide pins” that hold the pads inside the caliper and the retainer springs.
I think these are really the main things to look out for in the time being as the bike is still so young aswell
It’s a big ask, but when the engine is hot. Turn it off. Then take out both spark plugs.
Can you do a compression test on both cylinders at full throttle for a few seconds and tell us what PSi each piston cylinder is making ?
Ok will do thanks.
Check your PM fella. About your order on the way to you . Thanks!
Hi Marcel, The bike was registered in April 2021 and has had it’s first and only service, this was on 14/07/21 and was at 625 miles. The service book says that it should have had it’s second service at 2485 miles or 6 months from date of purchase. So it’s not reached the mileage yet but well past the 2nd service date. BTW I’m the 3rd owner. Thanks, Nik
Just to ask has the warranty been passed on to you if the bike was bought from a dealer ?
Any reciepts of work carried out on the bike so you can see the history of its life (what’s changed, whats fixed, whats fitted etc)
They are leds & no oil pressure warning which I find a bit odd, I have considered fitting one from the filter but not got round to it yet.
That i would like to see 😉
Around 5k to 9k rpm it starts to wake up and sling shot away lol but 10k is usually where it makes its peak power , for most cruisers to make power low down, this should not be able to rev to 13k revs yet it is a high revving bike in general and seems to like it (around the 9-10k mark is fine all day)
Though 11-13k is usually no go zone unless bike agress with it for overtaking purposes (slow traffic) , so i think the red zone is just there for momentary use. Lest the valves start floating & extra wear , but i digress sorry.
is it cold over there yet ? – It’s autum now and about 15-20c general temps , i miss summer already!
Nice to hear its made it to 1500 miles , what reciepts or information do you have of what has been done to the bike (every nook and cranny of it)
I can probably advise what to use and what things need looking at certain mileage , but i have to ask ? isn’t your dealer responsible for fixing anything with the bike or maintaining it to keep the warranty active ?
This also could be worth a shot;
Along the harness , near the middle of the tank there is a diode (rectangular) shape white objected tucked away inside the harness tape. That’s for neutral. Also check neutral sensor itself, swap for another neutral sensor if in doubt.
They are not in the UK market yet but as soon as i get hold of a good supplier, i will advise or list them , this is also often asked for the older GV carby bikes.
I am also sure Korea is making them as optional item for new bikes like they did in the past, i am keeping an eye.
I dare not advise chinese made parts on such heavy bike, we don’t know how well they produce their own parts for this bike or it could fall apart soon.
Not all hope is lost, you can get a bike lift that will rise up the bike from under the middle of the chassis so the whole bike is suspended in the air, pretty handy if wanting to take both wheels off even for whatever needs servicing on them.
People that have bought 520 chain kits on this site have used small bike lifts at home or garages did it for them.
You will find various lifts on Amazon Prime for getting it faster, if it is urgent. I wouldn’t use old fashioned car jacks but some people have done that & not yet dropped their bikes to the side yet! 🤐😬
Was the compression also tested when engine was hot warm & full throttle with both plugs out ?
Welcome to the site , that’s a colour that has my heart as i have a thing about blue or red bikes or stealth black haha
First of all, enjoy riding it, then on a calm weekend or a day , have a look to see what’s been done under the hood that isn’t suspicious
If the bike runs as it should then that’s awesome. All that’s left for you is how nice you want it to look (beauty is of the beholder!)
You haven’t said if its carb or EFi (and which EFi ECU it has as there is various, meaning it will use different electronics than its predecessor , ie coils , ecu , stators and the like )
General questions like servicing calipers , oil , fuel , filters etc can always be found in the technical section of this site (in older topics asked by others already) but if not, you’re always welcome to make a new technical question.
- Oil Change = Motul 7100 (no matter what he says) , premium oil is better than cheap poundland oil (some garages are known to use crap drums of oil in their workshop to save money as they fill it up on various customer bikes
