Tom
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Cost of living on the world isn’t going to make a rider fork out £1500 for an engine, they would get a whole bike for that! – 50+ units could work for a dealer though if they have a fleet of bikes and need spare engines for their customers in their workshops.
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I quite agree, £1500 for an engine is crazy, I could get a cloned Toyota 1zz-fe engine (Celica, Corolla etc) for around that price with shipping and customs included. Plus somebody could buy 2 or 3 Hyosung 125/250cc for about £1500 now they are getting on in age.
I am enjoying my sniff through China and have a couple of more ways to track stuff, but I feel it will lead to nowhere. The most likely to see a result is using 1688.com, suppliers are on there but you need the right Chinese search terms to find it and use the picture matching system. Then if they can be bought and shipped you will likely get the “not quite the same as OEM fitment issues” that I am seeing in comments for the cloned GT manifolds. I have ordered a set of the cloned GT manifolds for experimental purposes, as it is a simple process to make modified airbox funnels.
But the engines are in common use in China and they are in a quite a few bikes, so the parts may trickle through eventually. You can already get cylinder barrels, head gaskets, pistions, valves etc for the 250. I will not devote much more time to looking, the whole system is a minefield to navigate. I just love these bikes and have owned a couple now, instantly regretted selling the first so I went and bought another. It breaks my heart to see them dying for lack of parts, so even though it is likely to be fruitless I don’t see it as time wasted.
Not sure what happened there my reply showed error when I edited it because I missed out Yinxiang and Chongqing, then it vanished. So here is another attempt, I hope it is not a duplicate.
Plebeyo, you’re right that a horizontally oriented carb won’t behave properly if you try to run it vertically. Even if you could tweak the internal jet positioning, you’d still be into redesigning the float and bowl to make it work properly, which quickly turns into more trouble than it’s worth.
I was digging into the supply chain behind engines from Yinxiang , and it’s pretty complex. One thing that stands out is that part references don’t always mean exactly what you think they do. You’ll often see familiar names used even when the part itself has been modified or adapted.
A lot of that comes from how the industry is set up around Chongqing, where there’s a big cluster of manufacturers and shared suppliers. Designs, tooling, and parts tend to overlap quite a bit. Because of that, something labelled “PD26J” is usually more of a reference to the general design and fitment rather than a guarantee it’s identical to a Honda spec carb. It might look the same on the outside and bolt straight up, but internally it could be quite different depending on the supplier or the engine it’s meant for (like a V-twin setup).
So in a lot of cases, it’s really more “PD26J-type” than a true PD26J. Makes sense once you realise what’s going on, but from the outside it can be a bit of a headache to figure out what you’ve actually got. It can can really run you in circles.
So a CMX250 carb clone will not run a v-twin, but internally in the China supply chain the v-twin carb is still referred to as a PD26J.
For a carb replacement I would talk to M77 about it though the Hyoriders site contact to see if he has one available – he has an Ebay shop with parts, or look on Ebay for a GT/GV being broken for parts and contact the seller.
I have no idea how to PM people on the forum.
I need to do more hunting as the Yinxiang contact I found, Jinhau Kaichen Trading CO, LTD, have replied and want to sell entire engines by a minimum of 50 units and at nearly £1,500 an engine, then add shipping and customs makes it crazy pricing. Not a viable option, but I have not given up yet as there will be suppliers and factories rather than a trading company. I just have to dig deeper. Hopefully the realisation of the size of the market available will nudge one of these factories/suppliers to start selling parts, they will make good money doing so.
A very different experience to the Hangkai manufacturer Taizhou Gongda Motors, who I have dealt with and purchased from, they where very helpful and keen to sell the parts that were very hard to source in the UK for their Hangkai outboards. I cannot rate Taizhou Gongda Motors high enough, a very good company with very high quality products.
Pleyebo, I agree completely, any hardware is better than none. China is getting so much right now with their manufacturing, I hold out very high hopes of some good stuff. There is big market in UK and Europe for these parts, I hope the Chinese manufacturers grab the chance to take it. Just putting their products and parts on Aliexpress would be sufficent and avoid much of the European and UK red tape, EU warehouse issues, retailers etc. I am very excited at the prospect of these engines and parts becoming available outside of Asia.
That spec sheet you posted is a different write up of specs than I saw. So which company did you find? Here is the Yinxiang spec sheet, with their bore and stoke being 65×50 so giving you about 335cc. So there is variation out there. I want a 335cc engine to play with.
Please note a correction to the 350cc engine code I posted it is 2V64FMP not 2V67FMM as I originally posted. I should start wearing my reading glasses, but I can never find them LOL.
The carb below is the one quoted in the spec sheet for the 250cc – PD26J. The clone of the Honda 250 rebel carb. Looks very similar to the Hyosung carbs. 🙂
Yes, I know China is dodgy as it gets. Rubbers perish and dissolve, bearings don’t last, and made of the finest chinesium (guaranteed pure metal LOL). I would not give them my patterns or manufacturing as this is what they always do. But quality can be good at times, just not often, and not close to Hyosung quality control. If you look on the cylinders in the photo they do say GV 250 so it is a blatant copy. Makes me wonder who Hyosung farmed the work out to. I remember a famous pen manufacturer, maybe 20 years ago had trouble, 12hrs making for the client, 12 hrs making for chinese fake. There is no recourse for copywrite or IP rights if you find your product cloned in china. The cub engines have got quite good, but still a very hit and miss purchase. But if OEM parts are unavailable then it might be an answer, but not the preferred choice. Just see how it goes, it is interesting to see that they have cloned it as Hyosung are good engineers. I would like to get my hands on one of the engines and put it through its paces. I have good experience with Hangkai outboards, they are clones of Tohatsu, Yamaha and Mercury.
The engine shown is EFI so it would need stator and flywheel change for a carby set up.
I have not been on here for a while, but I had that exact issue on my carby GV125. So even though it is probably too late to help Twap it might help others. My airbox to carb funnels were shot, going hard, starting to shrink, and would not seal. All clamped properly but they let a small amount of air into the system. Result ok idle and started ok, but on throttle input you got what you saw in the video. If you could get it to rev past about 3.5k/4k it would rev up and climb but not smooth. I 3d printed a new set using TPU filament and cured it – been on bike for a few years now and still good. Hope this helps diagnostics for others. If you want to find that air leak spray carb cleaner and watch for a rev rise, might be very slight but that is enough to mess up cv carbs.
Hi John
The GV250 is the frame same etc size as the GV125. I am 6’4″ with a 34 inside leg and size 14 feet, I find my GV a lovely fit. I did play with the back brake pedal to make it a bit lower (put a longer adjuster bolt in).
Go for it, a GV250 is easy to work on and a joy to ride for the taller rider. At 950 Euros you will make money when you sell it on.
Thank you guys, do not worry she runs really well, is warmed up properly, has regular oil changes, lavished in ACF50 and isn’t thrashed. Just wanted to ensure that she would run well for good while longer as may be looking to sell her soon. I only like to sell on a good bike in good order, I want the new owner to have trouble free fun.
Quite glad I do not need to do the clearances as my attention is on an old ER5 that I got for peanuts. The ER5 had beed ridden until the clearances had tightened enough to mess up idle etc, the previous owner had looked for vacuum issues but did not think valves. She runs like a dream now, a noisy tatty old kwak 500 dream 😀
Bloomin hell, what a journey you are having.
Is it carb or EFi? Are you sure it was fuel not water that was the excess liquid?
For those reading this;
Hydro locking is where you have to much liquid in the cylinder. When the stroke of the piston goes to compress the fuel air mix the excess of liquid cannot be compressed by the piston. This means that something has to give. The result is usually a bent piston rod but it can shatter the cylinder walls/piston etc. This results is a seized engine due to the damaged internals.
The usual cause of hyro locking is water getting in the the cylinder chamber but can be caused by excess fuel etc.
If an engine is hydro locked, say from flooding, then removal of the spark plugs allows the excess liquid to flow out without damaging the engine internals.
Since the bike seems to be set up correctly, I would still suspect the oil. I was not familiar with the oil you used so looked it up at Eurocarparts and it is ACEA A3/B4 car oil (lots of additives for car engine longevity). The oil grade that is recommended by Marcel is JASO MA2 motorcycle oil, he has worked on many Hyosung twins and knows his stuff.
If an oil has additives to improve lubrication/cleanliness etc it can make the motorcycle’s wet clutch slip. Car oil often has these additives as the gearbox is usually seperate from the engine and they have a dry clutch. I have an austin Maxi auto and the gearbox has a wet clutch and shares the same oil as the engine (like a classic mini auto and most motorcycles). As such I have to use a classic low additive oil to ensure the clutch plates do not slip. It is the same principal for motorcycles as the engine and gearbox use the same oil with a wet clutch, you do not want an oil with additives that stick to the plates and allow the clutch to slip. It is always recommended to use motorcycle oil not car oil for this reason. There is lots on the internet about people using car oil and getting slipping clutches.
Halfords have a cheap JASO MA2 motorcycle specific oil, I would change it out and see if it improves. If it does improve it then change the oil again soon, try to think of the first oil change as an engine flush to get car oil additives out of engine. Dont forget the filter as that will hold lots of the car oil also, at the very least remove it and flush it out with the new motorcycle oil.
Here is a short article that explains it. https://itstillruns.com/reasons-motorcycle-clutch-slipping-8739449.html
Good luck and keep us posted.
I would say slippy clutch. Engine revs would climb without immediate speed increase, especially under high exceleration. How old is the oil/what oil have you used? Is clutch adjusted properly (where is biting point on clutch lever)?
https://powersportsguide.com/motorcycle-clutch-maintenance/ Here is loads on clutch adjustments and symptoms.
According to the service manual the compression service limit is 8kg (113psi), it should sit around 10-12kg (140-170psi). So you are at the service limit and it would indicate that things are a miss somewhere. Probably just valve clearance, if a valve stays open or does not open properly the compression is adversely affected and you get a rapid drop off in HP. Combine low compression with a slippy clutch, carb issues or exhaust leaking near the head then bike will be greatly under powered.
How old is the bike?
What mileage has it done?
Do you know its service history?
Service history is important because a bike set up properly with the correct oil etc will last and perform beautifully. If a bike has been run with low oil, wrong oil or even too much oil it can quickly damage the rings causing compression loss. Running a lean (hot) bike can also damage the piston and rings, I have seen pistons burned through from running lean. A discoloured exhaust is often a visual sign of a bike running too lean and hot.
If an owner just ignores dropping speeds and power loss it will mess things up badly, unfortunately the poorly cared for bike is often passed on to a new owner who has no idea a numpty did not care for it.
The first step I would take before assuming terrible things (you have not mentioned excessive exhaust smoke which would indicate rings) would be check the valve clearance. These are really tough little engines, but they need to be cared for.
Horse power depends on four things (presuming no sprocket changes etc).
1 Air
2 fuel
3 spark
4 compression
Thats the list, anything further than that would be internals and that would be evident.
Have you checked your compression? (Piston rings or valve clearance)
Oh thats not good, I do hope you were not hurt. Sounds like your OK as you are still riding her.
What damage did she sustain? What the happened?
When you have passed A2 what are you looking at purchasing? Staying cruiser? I am shopping around as Das in August and have been looking at Honda Shadow or VLX, but I would like a 250 GV as I love my 125 so much. Gv(C) has good riding position for tall riders, great looks and rides so well. I have to agree with Simon somehow these Hyosungs are heart stealers.
Good luck with it all Moustache Man.
Yes, I think you have found what you need. They are same engine.
Good luck and let us know how it goes.
Hi,
I would look at the other models Hyosung did in the 90’s early 2000’s. Strong likelyhood of the same engine.
I think the RX and GA may have same engine, you can compare online pictures of bikes to make sure.
This is the GA. Does engine look the same?
Here is a link to gasket set for GA.
I have found Mr Lee at HyosungSource reliable.
Good luck.
Sorry i made a mistake in my post, wont post late after a beer again.
You can ignore the engine cut off switch as you know it works from when you shorted the solenoid because the bike started and ran rich smelling. So checking that is pointless even if you are in the switch housing. Because she started this also means the clutch switch is probably ok.
Also, it is the start button and lights that often share a common 12v feed. That shared 12v input is split between the lightswitch and the starter button creating 2 different circuits (starter and lights) from one 12v fused input. The engine cut off switch, like the side stand and clutch switches, are part of a spark inhibitor circuit which means the engine will turn over but with no spark.
Eurocarparts have contact cleaner for £4.39 https://www.eurocarparts.com/p/holts-electrical-contact-cleaner-500ml-552996200
