Just got the GT250R rejetted

[Iain]

Finally, after getting my GT250R dynoed and rejetted its rides like a different bike - and I like it!

Cost a few hundy but definately worth it.

Ill be going for a ride this weekend with another Hyo rider and we will swap bikes so we can both comment on the difference. Ill post our thoughts later on.

Anyone else considering doing this on their GT250r?

Iain

[vifferman]

What was the aim of the rejetting? Was it running too lean/rich at some revs?

[xwhatsit]

What was the aim of the rejetting? Was it running too lean/rich at some revs?
It's a rare GT250R without some kind of mangled/aftermarket exhaust. They sound quite nice, TBH :) I don't think the carburettion is that shit-hot to begin with, at least from anecdotal stories you hear from owners. Might be the usual emissions story?

Interesting to see when the injected Hyos get to NZ.

[CB ARGH]

Interesting to see when the injected Hyos get to NZ.

Those look goodies :headbang:

[fizbin]

Finally, after getting my GT250R dynoed and rejetted its rides like a different bike - and I like it!

Cost a few hundy but definately worth it.

Ill be going for a ride this weekend with another Hyo rider and we will swap bikes so we can both comment on the difference. Ill post our thoughts later on.

Anyone else considering doing this on their GT250r?

Iain

How much did it cost you all up?:innocent:

[Iain]

How much did it cost you all up?:innocent:

I had it done with an 8000k service. I think the jetting and air filter and box modification was $350.

Iain

[WTB]

I've been thinking about the rejetting/airbox mod. and see JFK have done a few. Is the stock air filter replaced with a high flow job or the air box desnorkled...thanks.

[nivram]

I cound'nt justify the cost at the end ofvthe day if I want to go faster I will wait until I pass my test and get a bigger bike. But interesting to see the power gains.

[Iain]

I've been thinking about the rejetting/airbox mod. and see JFK have done a few. Is the stock air filter replaced with a high flow job or the air box desnorkled...thanks.

I bought my bike from JFK so didnt consider getting it done anywhere else actually. They do open up the air box. Give em a call and ask to speak to John or Lisa (the owners) about exactly what they do and what brand of air filter they use.

Did you get an exhaust for yours?

Iain

[WTB]

I bought my bike from JFK so didnt consider getting it done anywhere else actually. They do open up the air box. Give em a call and ask to speak to John or Lisa (the owners) about exactly what they do and what brand of air filter they use.

Did you get an exhaust for yours?

Iain

I purchased the screaming demon carbon pipe off ebay.au earlier in the year and see the rejet/air filter mod as the next step. I understand the gain is primarily in the low to mid range, just wondering if it is a noticable step in power or more to do with smoother delivery?

[Iain]

I purchased the screaming demon carbon pipe off ebay.au earlier in the year and see the rejet/air filter mod as the next step. I understand the gain is primarily in the low to mid range, just wondering if it is a noticable step in power or more to do with smoother delivery?

I got the Screamin Demon exhaust also. I notice increased power delivery mid to high range. Its much more responsive 6000rpm+ :niceone:

Iain

[mark247]

What was the increase in horsepower and torque?

[Gubb]

After doing the Exhaust, Air Box & Rejetting, mine gained about 9Hp.

[CookMySock]

I did the ignition mod on our two and didnt notice a thing.. :whistle:

But I don't ride them all the time, and the owner/riders are total newbs who rarely get past 2/3 throttle anyways.

DB

[Iain]

I did the ignition mod on our two and didnt notice a thing.. :whistle:

But I don't ride them all the time, and the owner/riders are total newbs who rarely get past 2/3 throttle anyways.

DB

I definately noticed a difference when I pulled the Brown wire :P I noticed gear changes were able to be made much quicker.

Do you have 2 fiddys as well as the 650r?

Iain

[mark247]

After doing the Exhaust, Air Box & Rejetting, mine gained about 9Hp.

fark thats a fair bit considering they are like 28hp standard.

[Gubb]

Yeah, it makes it better to ride, smoother power curve all the way through.

It still won't beat the 80's bikes, but I'm happy with the improvement, makes it easier to ride in traffic which is where it (unfortunately) gets most of it's use.

[xwhatsit]

fark thats a fair bit considering they are like 28hp standard.
Lol yes -- I'd be interested in seeing some before and after dyno charts for such a claim :sweatdrop

[mark247]

Lol yes -- I'd be interested in seeing some before and after dyno charts for such a claim :sweatdrop

yea me too. just comparing to the vfr. they are 59hp standard and you'd be lucky to get it up to 65 - 67hp with rejetting, new can, airbox etc.

[xwhatsit]

yea me too. just comparing to the vfr. they are 59hp standard and you'd be lucky to get it up to 65 - 67hp with rejetting, new can, airbox etc.
Boost any bike's horsepower by 30%, then I'm surprised the clutch and gearbox still hold together. Hell, boost any bike's horsepower by 30% without fiddling around with the internals then perhaps the MotoGP teams should start looking for you :Pokey:

Anyway, I'm just being nasty. Should let people retain their illusions and delusions -- everybody else around here does that with me and my `awesome' 250 :laugh:

[mark247]

Boost any bike's horsepower by 30%, then I'm surprised the clutch and gearbox still hold together. Hell, boost any bike's horsepower by 30% without fiddling around with the internals then perhaps the MotoGP teams should start looking for you :Pokey:

Anyway, I'm just being nasty. Should let people retain their illusions and delusions -- everybody else around here does that with me and my `awesome' 250 :laugh:

Everyones allowed to dream :bleh:

Maybe it's just the jetting on the hyosungs was pretty poor in the first place so rejetting made a HUGE improvement?

[Gubb]

Meh.

'tis what Phil at JFK told me. I couldn't really give a stuff either way, it works better for me.

[xwhatsit]

Meh.

'tis what Phil at JFK told me. I couldn't really give a stuff either way, it works better for me.
I agree there -- proper carburettion makes a huge difference in how ridable a bike is.

[WTB]

I did the ignition mod on our two and didnt notice a thing.. :whistle:

But I don't ride them all the time, and the owner/riders are total newbs who rarely get past 2/3 throttle anyways.

DB

For such a simple tweak, I found gear changes were alot more smoother and best of all the engine didn't bog anymore (4500-5000 rpm) under hard acceleration especially when you had dropped it down a gear or two.

[CookMySock]

I definately noticed a difference when I pulled the Brown wire :P I noticed gear changes were able to be made much quicker.

Do you have 2 fiddys as well as the 650r?

IainWhat I did notice, is they start really really easy now. Choke, start, instant response! Not like before - used to be a farty start when cold.

Yeah, we got two GT250R's and a GT650R. We'll have another one when the daughter hits 15. We should start sending pics to the importer! They might give us free stuff!

DB

[Filter_nz]

I'm in the same boat as Iain,
Screaming Demon exhaust from ebay.au
Jets done and filter/box mod
Didn't really notice much from the ECU wire mod thing

Bike actually seemed slower after the exhuast was done but after the filter and jets were done to match, it was much more fun to ride.

I'm keen to swap with a stock Hyo and feel the difference.

Iain did you notice when changing down a gear at high rpm the bike was smoother (and less likely to lock the rear end in the wet)?

[Iain]

I'm in the same boat as Iain,
Screaming Demon exhaust from ebay.au
Jets done and filter/box mod
Didn't really notice much from the ECU wire mod thing

Bike actually seemed slower after the exhuast was done but after the filter and jets were done to match, it was much more fun to ride.

I'm keen to swap with a stock Hyo and feel the difference.

Iain did you notice when changing down a gear at high rpm the bike was smoother (and less likely to lock the rear end in the wet)?

Definately mate, although I did find it easier to down shift after the ECU mod as the revs didnt seem to drop as quick so it found the lower gear easier.

I havent yet locked the rear wheel up in the wet yet - did it on a dry road and that was lots of fun - coming up to a red light and swear I hit some oil or crap on the road.

I found after rejetting my bike is much happier 7000rpm+. Ive since been practicing corners in a lower gear at higher RPM. Feels much better exiting in a lower gear at high RPM - exciting! Need some time on a track in a controlled environment to practice more!

Iain

[Iain]

I'm in the same boat as Iain,
Screaming Demon exhaust from ebay.au
Jets done and filter/box mod
Didn't really notice much from the ECU wire mod thing

Bike actually seemed slower after the exhuast was done but after the filter and jets were done to match, it was much more fun to ride.

I'm keen to swap with a stock Hyo and feel the difference.

Iain did you notice when changing down a gear at high rpm the bike was smoother (and less likely to lock the rear end in the wet)?

I've ended up with an AIS block off plate and gasket. Did you put that one when you got your work done? I got told about recirculating exhaust gasses and emmission control and rear cylinder getting too hot blah blah blah. I ordered a 'kit' that turned out to be a cheap plate and gasket. I dont know what I was thinking cause I could have made one myself but didnt get it fitted when I got the jets done. Forgot to bring it up in fact. I guess its not required?

Did you?

Iain