GV250 upgrade kit

[griffon_j9]

Good day to all

Just wondering if anyone here has purchased 300cc upgrade kit and installed it on there gv?? and if you did was there and improvements?  Just curious as I have been doing lots of web search surfing lately on scooters

thanks

[griffon_j9]

weeelllll by the response I got from this I am assuming either no one has tried it orrrr it is just a bad idea to replace the cylinder..... orrrr you have no idea what I am talking about and think I am crazy lol

so here is the link (hope this works)

http://scootertronics.com/ky250cyup30.html

maybe this will help shed some light.

thanks again

[Urbestfriend]

Urbestfriend agrees that this option may not be popular.  To say that it produces performance equal
to a Burgman could use a little data backing up.  What is the % hp. increase.  Do you need a new exhaust,
jets, tuning.  Knowing what we do.  $300.00 for an extra 50cc's is questionable.  Then again,  this could
be a more recent option on the market.   I've been more than happy with 250cc.   Being that most of
the fellow forum members have new bikes,  maybe they just don't plain have the money.  However...
I too would be willing to entertain comments on this package in the future.

[jprestonian]

Wow... I reckon there ARE more differences in the GV250 and the P250 than just the routing of the exhaust. That seems really inefficient to build two different 250cc engines.
.

[axy]

Wow... I reckon there ARE more differences in the GV250 and the P250 than just the routing of the exhaust. That seems really inefficient to build two different 250cc engines.
.

My mechanic told me that engines in Grand Dink 250, your People 250 and my 250 S are different.
Allegedly, S gives the highest output.

He also said what the differences are (bore, stroke, camshaft, valves etc.)

[zodiac927]

The old saying goes: If it aren’t broke don’t fix it.    Could be more trouble than it's worth. 

Rubber side down.
Zodaic 

[OldGuy]

My mechanic told me that engines in Grand Dink 250, your People 250 and my 250 S are different.
Allegedly, S gives the highest output.

He also said what the differences are (bore, stroke, camshaft, valves etc.)

According to KYMCO bore and stroke are the same. Go here:

http://www.wantfacts.com/clients/kymco/index.php?ProdType=MOT&TrimId=26445

and use the comparison feature to prove it to yourself. (Yes, can compare Kymco to Kymco.)

Camshaft, valves, etc. may be different although I doubt it. Any changes would require that each engine type would have to be EPA certified separately. A costly process when you consider the number of markets the 250 is sold in. Final gearing is most certainly different since the GV has 12" wheels and the People 250's have 16's. It may not fit the People simply due to space considerations.

As for the additional 50cc's being a big improvement, it is possible. As an example, back in the '60's it was discovered that over boring the Corvair engine by .030" had almost no effect while .035" of over bore made a huge difference. The reason was that the smaller bore left the valves shrouded by the cylinder walls. The extra .005 improved valve flow and turbulence. Weather that's the case here, I wouldn't know.

Another thing to consider. Reading the ad, I notice that they recommend changing the cam ($90.00) and the exhaust ($430.00) on top of the $230.00 for the over bore kit and this gets kinda pricey.

My last comment is an old engine builders quote, "The faster they go, the faster they blow."

My vote? Unless your Grandvista is just a sometimes short haul toy:Not Recommended!  Not Recommended!  Not Recommended!  Not Recommended!  Not Recommended!

[jprestonian]

Comparing the specs, I knew the S 250 had a little more horsepower, but am still not sure how it was achieved. I would have thought Kymco would have only made one 250cc engine, but that's apparently not the case (even though I don't know what the exact differences are between the bikes... I know there's a performance pipe available for the S 250 and the GV that are claimed to not work with the P250, but I had assumed that was only due to the bend in the exhaust prior to the muffler).
.

[garibaldi]

I recently installed the 300cc upgrade. But my scooter came to me broken, frozen rings, scored cylinder, blown head gasket, etc. I figured it would be about the same price to upgrade, rather than boring and hunting for the right piston, etc. So I don't know if it improved performance, as I didn't get to ride it before the upgrade. My searching showed no differences in the kymco 250 engines that I could find. Mine says "KHE7", and from what I could tell, parts are parts... I had bent valves too... just ordered parts for "kymco 250 khe7". Everything fit perfect. External stuff like exhaust pipe and air filters, etc. might be different due to body style alterations, but everything I looked at before doing this showed all the engines are the same internally.

The 300cc kit was a perfect swap out, nothing extra needing done. I can tell my carb needs some minor attention, but I fiddled with all the screws while it was apart, so that's expected. Don't know what to say beyond that. I haven't taken it past 45mph yet. I'm new to 2 wheels, and it's still a bit spooky when the wind gusts hit. lol. Wish I had another 250 to compare it with.

[zombie]

Not to bust you're thread. picking up an extra 50cc is a lot to a guy that rides a 50cc scoot. If I had a nickel for every mod. I made, I would be less broke!!!

[garibaldi]

I wouldn't have done this mod if the engine wasn't so toasted already... now a whole string of mods are screaming for my money! A better intake is needed to make use of this extra 50cc, which means new jetting, and then the exhaust HAS to be upgraded to get rid of all the extra air. Then there's the racing cam to take full advantage of this extra capacity. And of course a new CDI...  And I'm having hot dogs and ramen noodles for dinner tonight... poverty prevents stupidity at this time.

Fortunately this 300cc upgrade was a stand-alone bolt on scenario. The other mods can all be done later, if so desired, and as cash is available. And each one will bring significant improvements I'm sure.

[zombie]

I for one agree, if there is a quality after market string of parts that will open up options vs a plain jane rubuild, at the same cost... For me there would be no hesitation! Bigger is better.

[wordslinger]

Not to bust you're thread. picking up an extra 50cc is a lot to a guy that rides a 50cc scoot. If I had a nickel for every mod. I made, I would be less broke!!!

...i'd give my left cajone for another 50cc, so i would...

 

[drifter]

Installed a polini 300cc kit on myGV before, improved acceleration and top speed. Reached 153kph but with other performance parts installed, w/o the kit my top was around 140-145kph. Btw i am 6'2 and 240lbs

[zombie]

There are PLENTY of good kits for Kymco's. I love making something better...