Mods thread: Hyosung GT250R

[WarlockNZ]

Go to JFK in Manakau .. they do an awesome job.

Here's how it works. and having had it done to my old Hyosung i know what i'm talking about.

If you open the exhaust, the bike will start to run really lean, this is of course where you get more power, the leaner you run the quicker you go until the engine explodes.

In order to compensate for this, you have to increase fuel flo to bring it back to normal, of course if you increase the fuel, you have to also increase the air flo.

Make sense ?? .. good ...

The boys at JFK did my old bike and it made a massive difference, 10HP in fact, and they have tried all sorts of combos on a dyno to get it right.

I'm not going to tell you what the combo is, because JFK deserve the business, i would say, get it done by the pro's, they know what they are doing and it's not that expensive, if you already have the open flow exhaust, it's only about $140 i think.

On a side note, has anyone bought my old Hyo yet ???? hmmmm .. LOL

Oh and i still have an open pipe for a gtr if anyone wants it, not open enough that you have to re-jet, but open enough to sound shit hot

[Weaver]

i'm leaving mine to the pro's with the proper tools.

I'm leaving mine till I sell it and own a 600.
I had looked at doing some of the stuff that people here are talking about. But then again I only intend on having the bike for another year. I'd more rather put that $500 plus towards getting a bigger bike.

But Hubba Gubba is right. If you get your local bike shop to rejet it, it'll run well. But if you get it rejetted on a dyno, then it'll run at its best.

[Filter_nz]

Generally I agree with all the advice.
The jet kit I purchased includes the air filter and instructions for the air box modification. It also includes various tools and instructions to de-baffle the stock exhaust. The seller says it took ages to perfect the combination and will not tell anyone what jets etc he's gone with. I checked with other customers who can't rave enough... so fingers crossed. I'm pretty savvy with working on car engines and have most of the tools so shouldn't be a prob.
I'll photo document the kit and the install for anyone interested..... unless it blows my bike up and totally running like rubbish, in which case I will lie to you all and say how awesome it to avoid the "I told you so's"

[Gubb]

So you bought a jet kit without knowing the specs of it?

Good luck mate, hope you don't get too burnt.

[Filter_nz]

Ok time to update.. It took me about 4 hours to do but it's done.
On the GT250R..

Had to take the ferrings off and remove the carbs altogether. The instructions say you don't need to remove them but IF you don't you'll strip the screw heads trying to get the carbs apart.

Here is a summary of the upgrade:

1) Upgraded pilot jets

2) Main jets
Front: 92 upgraded to 95
Rear: 95 upgraded to 97.5

3) Jet needles
Stock on position 2 (of a possible 3) Moved to position 3 which increases mid range flow. (actually sits lower the even position 3 with a spaced washer). Lowering the position effectively raises the needle out of the jet

4) Air filter
Modified the stock filter by removing the stupid tiny intake core, intake is now more than double the size


MODS ALREADY DONE

5) CDI retard wire removed

6) Screaming Demon free-flow exhaust


Thoughts:
The bike runs Noticeably better.
Smoother, faster power through the whole rev range, shifting down a gear is a LOT smoother and less likely to lock the rear tyre at high rpm. For some reason I am a little disappointed... but there is no question the bike is quicker, smoother and a lot more torque under 5,000rpm. Top end is also much nicer for passing in the 100km zone.
I am picking I've gone from the stock 28hp to around 35hp which I think is great considering I spent less than $400 for everything and only 5k for the bike (with 3000km on the clock).

If you already have a free-flow or debaffled muffler, modifiying the air box and raising the jet needles is an easy and CHEAP way to get some power. Changing the jets was a lot more tricky and requied a few extra tools.

[Hitcher]

Please keep this thread on topic and desist from the cheap personal attacks. They do you no credit.

Several off-topic posts have been relocated to the Pointless Drivel thread. If you want to continue that discussion, please do so there. In accordance, of course, with the site's rules, that I urge you to familiarise yourselves with.

Thank you.

[Donut]

Photo?

I have some red "neons" under mu 50cc scooter to piss off the boy racers

will try get a photo on when i fix the camera

[Paul_C]

Hey Filter,

Just put my order in for a Screaming Demon pipe and will be ordering a new air filter in a few days.

Just a quick question, how much did you pay for your rejetting kit? Obviously the kit you bought had the correct settings etc included?

How much did it cost?

Does anyone know how much it would cost to get rejetting done at a dealer?

Cheers for your help.
Paul

[Gubb]

Complete re-post, but I figured it's relevant in here too. For those that aren't aware, I recently had my first stack Only casualty was the Gear Lever, and Indicator.

Got bored in the Waitangi day sun. I figured everyone else was out riding, so I had to have a bike fix anyway.

Managed to pick up everything I needed at Bunnings.
I bought 4 washers, 2 nuts, 1 bolt, 1 piece of rubber tube (5cm), 1 piece of garden hose (5cm).

Drilled a hole in the actual lever, coloured everything black with a Sharpie first, as I at least wanted it to not look like a rangi-mod. Placed a washer onto the bolt, followed by the rubber tubing, then the rubber hose. I wanted to put something underneath the hose as it was too loose by itself. Cut these to length with the Missus' good kitchen knife. Luckily she wasn't home to see this, as I would have ended up wearing the knife. Slid another washer on over the end of the hose, nut, placed it through the lever, another washer, and the final lock nut, and Presto! instant Gear Lever.

Total cost, $2.60 and 15 minutes. Much cheaper than the $100 it would have cost me to buy from a dealer.

Tested it, and the clearance between the lever and the pedal is sweet, works just like a bought one.


Pics Here.

[nivram]

If I'm only fitting an SD Muffler why would I have to re jet? If I was doing the air filter as well then I would re jet.

[Gubb]

I have had no issues with the Muffler and not re-jetting, that was about 3000Km ago now, and no issues yet.

However I am planning on getting the Airbox done, and re-jetting at the same time.

[nivram]

Same I've been running SD muffler without an re jetting and the bike runs fine not too lean at all.

[Gubb]

I had mine checked after I put it on to see if it was running too lean, the Mechanic said it was sweet as, but as soon as you go and modify the air-flow, and don't re-jet, you will have problems.

[nivram]

Just removed the wire hope it resolves the flat spot, has to be the quickest easiest mod ever!

[Filter_nz]

Hey Filter,

Just put my order in for a Screaming Demon pipe and will be ordering a new air filter in a few days.

Just a quick question, how much did you pay for your rejetting kit? Obviously the kit you bought had the correct settings etc included?

How much did it cost?

Does anyone know how much it would cost to get rejetting done at a dealer?

Cheers for your help.
Paul

hmmm not sure I want to tell people, I want the fast Hyobag around town.
Seriously though, I got it for about $90nz inc shipping from EBAY.

It took me about 4 hours to do and unless you remove the carbs altogether you'll probally strip all the screws

If you take it to a mech they'll probally drop the jet needles down one position and call it a "rejet". And to be fair it'll work... doing that increases mid range fuel flow which is where you'll have the bike when curising... and so won't be running lean. Just dropping the needles is a cheap, easy and safe way to make sure your straight through and air filter don't lean you out. Will gain a bit of power too. You can do it youself if you want me to explain.

If I could to it all over again I wouldn't have bothered with the jets themselves.