Hyosung fine at 100km/h?

**McJim** · 29th March 2009, 21:41

Originally Posted by disenfranchised

I think you'll find that isn't possible.....same gear + same revs = same speed
It's a fixed equation.

The laws of physics don't apply to Hyosungs - haven't you seen the "I'm gonna mod my Ho'bag until Hyosung sponsor me in GP 250" thread?

Unless of course it was suffering from some sort of uniform clutch slippage at cold temps?

I think what Hiflyer was referring to was that the bikes tend to rev out easier once warm. Just because he is no seasoned rider and mechanical genius like yourself doesn't mean you can go around pissing on his bonfire.

cut the fella some slack.

**Hiflyer** · 29th March 2009, 21:42

ok well thats just what i found, maybe the speedo was out even more than usual with the heat? it certainly had more oomph than it usually did

**DarkLord** · 29th March 2009, 22:11

Hey Riding - just wondering, does your Hyo backfire at all? I got my Demon installed a week ago and it backfires like a mad thing....lol. I've had the sparkplugs checked and it's not running lean or anything, just wondering if other Hyos do it too!

**xwhatsit** · 29th March 2009, 22:21

Originally Posted by DarkLord

Hey Riding - just wondering, does your Hyo backfire at all? I got my Demon installed a week ago and it backfires like a mad thing....lol. I've had the sparkplugs checked and it's not running lean or anything, just wondering if other Hyos do it too!

I take it you're talking about popping and crackling when you close the throttle, rather than actual backfiring? If so, for some colloquial evidence, the one person I know with a Screaming Demon on their GT250R has very quiet popping and ticking on the overrun. Certainly nothing particularly noticeable.

Check for exhaust leaks along the full length of the system, from where the headers join to the engine to where the can joins the headers.

**DarkLord** · 29th March 2009, 22:38

Ah, yes, that explains it. I think there are some small holes in the bottom of the header pipes - had to cut the thing right open as something inside it was rattling. I think there may be a small hole not completely patched up.

It is when I close off the throttle, but full on backfiring - not just popping and crackling. I'm not too worried then - the headers are pretty wasted anyway (had a crack in the header pipe from the front cylinder and everything rattles around like crazy) I'm probably going to look at getting the headers replaced sometime anyway.

**xwhatsit** · 29th March 2009, 22:42

It would just be popping and crackling normally, but due to your loud not-very-silencer stuck on the end of the headers, the exploding fuel mixture in the exhaust system doesn't get muffled very well and you hear the full effect.

Night and day difference on my aftermarket 'zorst for my RS; full-on explosions whenever I buttoned off. Then I fitted new exhaust port gaskets and not only is the whole thing quieter, but the explosions are now merely a pleasant background twitter.

**davebullet** · 30th March 2009, 07:10

Hard acceleration and poor quality oil are probably more damaging than sustaining a certain number of revs in a 4 stroke engine.

Most 250 vtwins will rev > 1/2 their range to reach 100. The VTR250 pulls about 7,000 with a 11,500 redline.

**BiK3RChiK** · 30th March 2009, 09:09

Originally Posted by Hiflyer

so did I! well on saturday, and yea my bike didnt miss a beat either

, did you find as the bike heated up it performed better? ie doing higher speeds at lower revs than usual??

Yeah, she sure went well. I was real pleased. A friend and I stayed at Hahei and we did some tramping and sunbathing and relaxing around that area. It was awesome! The ride back yesterday was fantastic

**CookMySock** · 30th March 2009, 09:31

Originally Posted by DarkLord

Ah, yes, that explains it. I think there are some small holes in the bottom of the header pipes - had to cut the thing right open as something inside it was rattling. I think there may be a small hole not completely patched up.

This is a common fault. Did you do the repair? What else can you tell us about it? I have two bikes to fix.. one of them sounds like a stone in a tin can.

Originally Posted by DarkLord

It is when I close off the throttle, but full on backfiring - not just popping and crackling. I'm not too worried then - the headers are pretty wasted anyway (had a crack in the header pipe from the front cylinder and everything rattles around like crazy) I'm probably going to look at getting the headers replaced sometime anyway.

Any leaks in the front pipes will make it backfire loudly on overrun. The welding job on the headers is a little, er, economical.. and it leaks exhaust out, and air in at different times. I think they have done this on purpose.

Steve

**DarkLord** · 30th March 2009, 10:39

I was out riding one day and I all of a sudden started to get this horrible jarring rattle coming from somewhere down near the engine. I was quite concerned at first, but I quickly realised the engine itself still sounded the same and it wasn't being affected at all. I took it to my mate in Aucks who is a bike mechanic by trade and we took the exhaust apart one evening.

It turns out that the header pipe from the front cylinder had cracked and split in half as there are two pipes - an outer one and an inner one. The inner one had split and was jarring against itself when riding, creating this horrible noise.

The only way to fix it was to drill a hole in the outer pipe and weld the inner pipe and the outer pipe together to hold the thing in place, however seeing as it's still making that noise (admittedly not as loud as before) I wonder if it has come loose or another part has cracked.

The whole header system on the Hyo is crap anyway - once I find employment I'm half thinking of just getting the whole bloody thing replaced.