♠️ M77
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We haven’t got any makers in UK to recommend sadly as we have an exhaust maker called BLACK WIDOW but they only make pipes for the GT250/Gt125 now and we have Leovince in Italy that’s still making pipes for the lower CC class.
So the ST7 might need to use its own stock pipes or provide your stock pipes to a local exhaust fabricator to see if he can do any custom work for you ? Hey , he might open a new market for hgimself?
Or make some kind of “Y” shape pipe can be fabricated for you to join to the 2 pipes in to a single 51mm outlet which lets you use most full size 51mm mufflers ?
Yeah retrofitting a GT harness in to a GV is a whole different ball game , not something most people talk about , its actually rare , so you are pretty much in uncharted waters! Good luck .
If that hitachi thing is close to the cylinder head, it is probably injector but can’t tell as i can’t see the throttle body fully and how it goes in.
Lamda Sensor , and certain EFi sensors actually come from Hyosung MS3 250 Scooter (which is a super rare scooter in this country)
I’ve ever only worked on a sentec bike maybe 3 times , as simon said , never saw a TPS module that’s why i wanted to see your pictures as to where the TPS is.
It might be my eyes but i see 1x air sensor (Delphi type) on one throttle body, if it says “Delphi” on it. The “Mini Harness” that is connecting the throttle body sensors will have numbers like 12345 (DEL) , then it means (DEL) for Early Delphi unit. with a green tag , daewoo is yellow tag most of the time.
So have a Sentec GV harness , I have not found any other compatible harnesses. GV is harder than GT. Sentec is for Sentec. However it is possible to find yourself some sensors from a 2007/2008 GT250 (only one) , as after 2009 it was all Daewoo & Delphi afterwards
Welcome,
Have you take it to the nearest hyosung dealer near you to see if they can diagnose it ?
Or can you ask the previous owner for history of this bike so it’s easier to diagnose what’s wrong with it. Engine check light could be anytime , sometimes it just means dealer needs to reset it after service
We need more….
He is saying the floats and the float seats are the cause for #2 and #3 , if the bike is straight , revs go up and bike is on side stand then revs drop down (it is also harder to start in this position.)
So you need to make sure the float height is 7mm exactly and it should lift to about to 14-17mm. The “needle” on the float seat, should also have a healthy spring on it
So that when the float is lifted, you hear a nice little bounce sound when the float falls back down in to the carb = Instead of a “thud / bang” sound , this will likely jam floats in the future.
So in other words , #2 and #3 is float height issues as Cobra was saying
The red circular plugs can be ignored , they are for diagnostics.
White circle plug = It is called “2.8mm / 2.6mm Male & Female 2 Pin Car Connector” (common in older cars before the age of waterproof connectors)
Sentec sometimes uses Daewoo parts so , this is an area of ambuguity until things got finalised in 2014 when all things was just delphi for delphi (every little thing)
So can you post pictures of your parts that’s present on the bike , so i can see if i have old versions on ebay that could help.
Namely these only as you said “MAP sensor, throttle position and idle speed control unit”
hmmm thats suggesting , potential valve seat oil leak + overheating.
try fresh plugs (brand new ones) , take them out again and let us know. I’d be more concerned of the white cone in the middle, it needs to be muddy light brown (like clay)
any 5/8 cylinder or any honda/kawasaki bike that has 2 discs locally in your area. Use their lever and their cylinder.
Hyosung levers usually want Hyosung cylinders
just run away from aliexpress or ebay fakes , your brakes are very important!
Sounds like the crap ebay kits made from China by aliexpress sellers flocking to ebay , too cheap to be true usually means issues later.
Send us an email (click here) for whatever you need and I will make sure it is all retail japanese parts for a japanese carb
Float Height = See this topic (click here……) and look for my reply that shows the picture of the correct float height
(do not worry, GT125 uses the same carbs as the 250cc , it is just down-jetted to for 125cc that’s all)
Other parameters like float height is the same on both 125cc & 250ccAny time you get stuck with something during your rebuild, take a photo and post it on here so we can see what’s up!
Don’t forget to replace intake o-rings like these…. = These can help with rough running, incase bike is leaking air under the rubber intake boots! (often overlooked)
oooooo, that’s a lot to take in.
How about this , disconnect all switches at the front (left & right ones) , clean them, and while at it, be sure the wire colours match the other end going to the harness.
You want to be sure the previous owner didn’t use a GV650 switch on a GT650, that has crossed or missing pins.
Switch gear out of the way, next stage is to check your harness for any signs of shorting……
GREEN WIRE + BLACK (2 pin bullet connectors for your turn signal lights) = is always the right side of the bike. = For indicators (Turn Signals)
Bulbs = 10w max (no matter what) , it must be 10w (not less, not more) exactly 10 watts ===> Each bulb for all 4 indicators (meaning you have 40w total)
The relay must be OEM = If its fishy , replace it and see if that helps.
LED indicators need LED relays = 99% of anything LED is made in china , so expect funny behaviour or be lucky you have a good set. I hate LED’s , so call me biased lol. I find the Halogen life easier haha or i’m just old!
Keep the tail lights UNPLUGGED (RED Brake combination tail & License Plate Illumination)
You want to be sure the Turn Signals work as intended , before pluging all other lights back in , otherwise we have tio start again from above ^ until a culprit was spotted.
You got this!
There is a tutorial on the site , that helps you rich the current jets without really needing to upgrade them. Type in “Slide Mod” in the search box of the site. See how she runs , look at your plugs, if they are brown all over, leave it there.
If in doubt, take 4 photos = 2x Front 2x rear (eg. for front plug = 1 photo showing the inside of the plug and other photo showing the the spiral threads to see how dark they get based on heat)
Do this with fresh air filter (just get another stock air filter) and get CR8E plugs again (not CR7 or CR9 , if someone tells you to get CR7 , question their brains!)
@mf448kxn6 thanks, the acorn nut might as well be made from cheese! – I was able to extract the thread – just need a replacement. I’m confused over the main jets though – the GT250 parts catalogue states 95/97.5 (front/rear) with the stock exhaust. My GT250 has a stock exhaust (and is staying stock) – the jets are 92.5/95 – based on your comments, I should stick with these?
yes, that’s fine those current jets in your bike are more than sufficient.
All factory bikes i’ve worked on = 92.5 front , 95 rear on the 250cc models.
I wrote 95 front and 97.5 as upgrade jets because people start using freeflow pipes like black widow stainless and use proper afternarket cans such as Lextek OP1 , Black widow cans , MTC cans (not the crappy stubbies from china) and they put K&N air filters (not cones!) – never use cones.
This is to stop the bike leaning out on full throttlePilot Jets are size 20 front and rear, forever. (this size is more than sufficient for a 400cc even), so no need to upgrade.
The nut that snapped is called HOLLOW BRASS ACORN NUT , you will find it at the shop (purple button right at the top of the site black bar), it is very fragile! 👀
if the carb is that dirty , i implore you to change the INTAKE ORINGS that sit under the rubber sockets going the cylinders (inlet manifolds) , same rings are at the shop , use stainless bolts everywhere possible!!!
Other carbs = big money to a wizard to make airbox and new manifolds , cables , then carb tuning etc to make hyosung engine happy to run it.
Mikuni being japanese is a good carb if the last owners did not piss them off, so i can understand your frustrations.
you have to explain in a lot of detail what it is doing ?
how does it start?
how does it idle?
is it worse when hot ?
what rpm is best for her ?
which rpms does it bog down bad?
have you replaced the pump ?
are fuel lines and vacuum lines kinked?
is the tap on the tank replaced or did you clean it ? (it has dirt trap at bottom too like a big square nut)
what size pilot jets?
what size mains?
go to mixture screws , replaced them? the rubber orings may have gone bad and is leaking out
did mixture screws got touched ? how many full turns out are they ?
as cobra says = float height is key
Glad you got that resolved 😉 , yes Hyosung uses the same tube for GTR bikes that have shorter cables , and your naked GT is longer, so it helps to adjust to suit your comfort. who knows if the previous owner did things the wrong way!
Welcome to both you and the young mechanic in your garage!
tutorial for egr block off is in tutorials section even for the 650cc is the same principal
tank – how will you know you have low fuel ? the bike behaves worse when fuel level is too low in tank (as quoted from service book)
the vacuum taps are okay , they work nicely with vacuum pump – i tried bypassing, the bikes hate it. so respect to korea for leaving the pump on the frame for high speed runs
so far we are okay, just be patient extracting the exhaust off lol.
