blackout

***UPDATE. for anyone considering a hyosung, i have to mention that this drama was caused by bad gas sitting in the tank for the entire winter. a $10 bottle of fuel system cleaner and it runs perfectly fine. there never was any bent valve, or any severe engine damage. again, i'm right back to my original position of this being a fantastic starter bike, and far better quality than its reputation would imply. i'll leave the rest of my posts alone for integrity's sake, but again, THERE NEVER WAS ANY CATASTROPHIC ENGINE DAMAGE, THE BIKE RUNS PERFECTLY FINE.***

on my way home today as i turn on independence from shore drive, i did my typical winding out 2nd gear-to-redline (that obviously means i redline all day, every day!!!) acceleration on my little hyosung 250. just as it crept up to the 10,500 rpm redline, the bike stumbled and i suddenly lost a ton of power (if you can call what a 250 puts out 'power'...), and i found myself struggling to maintain 50 mph even at full throttle. i limped the bike home, fucked around with some of the plug wires hoping it was something that simple, and hopped back on... same thing. the bike just won't rev past about 4500-5000 rpm in any gear, and i can smell a pretty significant amount of fuel.

the bike's carbureted, and air-cooled. the idle seems ok, maybe a slight miss. i can't notice any knock or anything like that... just lack of power and a bad miss under acceleration.

anybody got any ideas if it's something simple i could fix myself? it's still under warranty so i'm not stressing too much, i just would like to avoid having to find a way to get it to the eastern shore to have it looked at.

edited just for carter.

skr00zloose

shouldn't be smacking the rev limiter like that on a korean made motorcycle. Thier quality of materials used is uh... lacking... to say the least.

That being said, since you were at high rpm when it happened, I'd be willing to bet you have some valve float, valve(s) hit pistons, and you bent a valve slightly.

Not saying that's it 100%, just an educated guess. I have plenty of experience with valve float:

this is what happens with severe cases (my 750 motor from my old 'fighter)

the only thing holding the 2 halves of the piston together is the rings and the wrist pin




check out the bend in the rod

blackout

well... it's supposedly a suzuki motor... hyosung apparently made engines for suzuki as a subcontractor originally before they decided to market their own brand of motorcycles. but after this shit my confidence in this motor has been shaken for obvious reasons...

i'm thinking bent valve as well. was just wondering if the fuel smell could tip anybody off to something else i could try before i took a trip to the eastern shore for the warranty work.

skr00zloose

every time you get a mis-fire, you get unburnt fuel dumped into the exhaust, hence the smell. A bent valve kills compression, so you get alot of mis-fires.

and hyosung bought the rights to produce the motor from suzuki, not the other way around. Happens alot, old (good) jap designs sold to the highest bidder, then said bidder builds the motors with inferior materials, to keep costs down. That's why you can buy all the funky chinese scooters with honda knock-off motors in them for so cheap.

blackout

definitely makes sense. up until now i had no complaints with this bike, but fuck man, this thing only has 1200 miles on it, i don't 'beat it up', and it bends a valve. shit.

at least the warranty is 2 years unlimited mileage, and should definitely cover this.

off to the eastern shore i go.

Voodoo ST

I concur with Steves diagnosis....

skr00zloose

well, to be fair, you did say you did the whole "redline" thing every time you hit that stretch of road.

In any case, all it takes is a weak valve spring (remember what I said about the quality of materials??) and high RPM and it'll eventually do some damage.

At least it's under warranty, hopefully they'll honor it and fix it. I wouldn't tell em you redline the bike often if I was you though, lol.

If it does turn out to be a bent valve, make sure they check out the piston and rod, for obvious reasons. it doesn't just bend itself, so they need to check the associated parts.

blackout

right, i do get on it every now and then, but in all fairness to myself, 'redline' very rarely even comes close, i'll maybe take it up to right about 10k, max is 10.5k... in this case it got closer than usual, and may have actually slipped into the red. there is no rev limiter, so i have to pay close attention to where the needle's at... i suppose it was possible i wasn't paying as much attention as i thought... or the tach is a touch slow... or something.

it's a god damn 250, it practically can't get out of its own way until it hits about 8000 rpm.

to be fair, i suppose i did kill the bike. i'm pretty sure if i hadn't wound it out today it would be just fine right now... it definitely didn't break by itself.

i'm still pretty pissed though. i've beat the everliving shit out of nearly every car i've ever owned, including multiple trips up to, on, and past the manufacturer's recommended maximum engine speed. i was always under the impression that engines were designed to perform within that range with no ill effects, no matter how many times you take it near the limit... as long as you didn't go over the redline (which i still think i stayed under, even if it was just barely under...) no serious damage should take place.

fuck it. i suppose i wouldn't be able to get shit for a trade-in, and i owe too much to try to sell it after it gets fixed...

skr00zloose

no offense, but there's a BIG quality difference between pretty much any car out there (except maybe a daiwoo) and any hyosung product.

not that it really matters, shit can happen regardless. Those pics I posted of my old 750 motor... that happened at about 10K rpm, and redline was 12K.

At least it's under warranty though, could be worse.

crxnfx

what are the possibilities of you actually fixing it? It can't be that hard to swap out pistons, replace the valve and the rest of the work that goes with it. yes, you'll be down a 250, but the parts should be relatively cheap, and you get to keep the bike.