hyosung gv 250 eco mod help

[johnathanf1lm]

I'm bringing out my bike out of hibernation this weekend and I fingered I would start eco modding it. Only problem is I do a lot of up hill driving so gear uping is off the grid. I also would prefer not to cage my bike either I like how it looks. Any ideas

[cRiPpLe_rOoStEr]

Is yours fitted with EFI or carburettor-fed?

[johnathanf1lm]

I wish it was efi, its a Carb. I may get it rejetted since the last owner of it hack sawed the muffler off so its just straight pipes.

[cRiPpLe_rOoStEr]

Since you wouldn't want to make it look too different from factory, you'll need to invest on the engine. Carburettor jetting, ignition timing, camshafts profile, among many other factors, can improve significantly the efficiency on your engine. Too bad it doesn't seem so easy to find aftermarket cams for a Hyosung bike...

[mechman600]

Originally Posted by johnathanf1lm

Only problem is I do a lot of up hill driving so gear uping is off the grid.

I would still gear up 10-15%. You will be surprised how your bike will still do up the hills - just a gear down from what you are used to. I would also leave the jetting stock, unless it doesn't run well with the chopped pipe.

The main thing to remember is to stay ducked down as low as possible when riding, hiding behind the windscreen as much as possible. This will make a bigger difference than any mods you will do.

Also, practice your EOCing - it's actually quite easy on a bike:
When coasting, pull the clutch, turn the kill switch off, wait till the engine has stopped, then turn the kill switch on (right away to avoid an awkward moment when you need to accelerate again). Keep the clutch pulled and stay in gear. If you come to stop, gear down as you slow down for the stop, all with engine off. Start the engine with the starter if accelerating from a stop or slow speed, or bump start it if accelerating from a faster speed, say 15 mph or higher.

You may need to use a battery maintainer when your bike is parked because your charging system might not keep up if you EOC a lot.

A compression ratio bump is actually quite easy on some bike engines. If the cylinder(s) is/are separate from the crankcase, eliminate the base gasket and use an RTV sealant instead. This will get the piston higher in the cylinder at TDC. This will also retard the cam timing slightly because of the slightly shorter distance from camshaft to crankshaft, which some guys here say improves economy by creating an Atkinson-effect (delaying intake valve closing) and also makes the compression increase less dangerous by keeping the dynamic compression ratio at a reasonable level.

[alvaro84]

Originally Posted by mechman600

I would still gear up 10-15%. You will be surprised how your bike will still do up the hills - just a gear down from what you are used to.

...

Also, practice your EOCing - it's actually quite easy on a bike:
When coasting, pull the clutch, turn the kill switch off, wait till the engine has stopped, then turn the kill switch on (right away to avoid an awkward moment when you need to accelerate again). Keep the clutch pulled and stay in gear. If you come to stop, gear down as you slow down for the stop, all with engine off. Start the engine with the starter if accelerating from a stop or slow speed, or bump start it if accelerating from a faster speed, say 15 mph or higher.

We'll gear up our GV250 by one tooth on the front sprocket, to try how the FE changes.

Also, bump start is quite easy and smooth on a GV250. On my 650cc single cylinder BMW I just can't make it smooth no matter how hard I try. So I use the starter instead.

About battery drainage: I never had problems with EOCing in the summer (with the F650, not the GV250 - but my girlfriend does EOC the GV250 too ). At winter, though, I could drain the battery. Using heated gloves doesn't help either...

[johnathanf1lm]

Well my ride to school I can't kill the engine really (no straight roads spreads are around 40ish and its up then down) mine doesn't have the optional windshield either. I may look into the gearing but there is a part were I stop turn then go up a pretty steep hill where the speed limit is 50 lol. Well that's the back way. If I take the highway there's no hill. Only prob is the it bogs and sometimes stalls out(rarely) at 5-6000ish rpm but then is fine after that (last owner was an idiot and tried making it go faster and louder and never properly stored and serviced the bike so its prob gummed up a tad)

[johnathanf1lm]

Sorry if I wasn't clear in the last message. Basically to school besides the one part where is straight downhill for half a mile I never coast.

[alvaro84]

Originally Posted by johnathanf1lm

Only prob is the it bogs and sometimes stalls out(rarely) at 5-6000ish rpm but then is fine after that (last owner was an idiot and tried making it go faster and louder and never properly stored and serviced the bike so its prob gummed up a tad)

Getting held up at ~5500 for a short while is a common problem with the older, carb'd model, not a peculiar whim of your bike - but stalling must be (if I understand correctly).

You can avoid this by accelerating through 5500 in 3rd. No joking here, it always helps with Ciliegia (our GV250), that 'hole' only shows in higher gears. Revving a bit when accelerating briskly doesn't really hurt FE, you're at the best part of the bike's BSFC. Then you can shift into 5th immediately when you're at the speed you aim for (because unnecessary revving with low load at cruising is the bad thing).

Anyway, it's not a big problem if you can't EOC on your commute. You still can glide simply with the clutch in downhills, that 250cc V2 won't eat too much at idle. And, of course, anytime when you want to slow down. Engine brake may be beneficial when you have to moderate your speed on steep downhills, but is just a waste of fuel when you have plenty of space to slow down (it uses [actual rpm / idle rpm] times more fuel than engine on coasting, and infinite times more than engine off coasting while converting precious momentum into heat at the same time).

[renault_megane_dci]

If you don't want to change the looks of the bike then the best nut to adjust is the one behind the bars ;-)

Try to source a decent exhaust, straight through exhaust rob power from low down rpm and rewards you with noise ...

My GN does 75 to 80 mpg not trying very hard, what does a GV do ?