Gt200

[Micah / AF1 Racing]

Not sure which came first, blown coolant out-pipe from the head, blown head gasket or failed water pump. I do know that the result was only a warped head and a seized piston though, far less damage than I expected. Owner said he saw temp gauge reading higher then normal, then miles down the highway later it was fully at the top of the temp scale, then a few miles later ot was flashing a warning and radically loosing power? At this point it was ridden about 2 miles further yet to a safe place to get off the highway. I assume coolant/head temps went over 250-300f.

It will be very interesting to see just what can be had of a creative mix of all OEM parts. His bike should run pretty shit-hot, with all the civility of stock and getting really good fuel efficiency too, while staying whisper quiet.

Fun project. I cannot for your new Malossi cyli der head to arrive. Of course it will get the normal supersport porting job before final assembly. For your bike I have been looking at carb options in case we find that the stock carb is limiting the fun factor!

[Micah / AF1 Racing]

BTW, sincere thanks, on the offer of your old head if we need it. I want to try my repaired head but if it is a failure I will take you up on your offer. The stock cam is far from pussy btw, just something I noticed. I guess with micro valves they decided to give it as much cam as they could on the 250cc Vespa gts.

[jrflanne]

Well, they expect the head "any day now". I'll just donate the old head to you guys since I have no use for it. Malossi has a 34mm carb kit in Europe but I don't know if it can be sourced in the USA. Power. I need more.

[Micah / AF1 Racing]

FCR32-34mm FlatSlide! Big K&N pod filter, loud and proud. I know we can find one of those in the USA! Even a decent 34mm CV Card repurposed from a street bike built a decade back would make a radical improvement in intake airflow!

One step at a time. It shall end up wicked!

[Micah / AF1 Racing]

So I have noticed something interesting on the 250cc motor at least, there APPEARS to be a 2lb removable flywheel weight on the stator end of the crank...hmmm, that seems like it might fall off on your motor Jack, that much extra flywheel mass on a 250cc single will make a difference you can feel for sure both in terms of motor response and acceleration! Anyone know if the the 200-300cc motors have been modded by removing this weight before?

[Micah / AF1 Racing]

This is the stock head from the GT200, GTS/GTV 250/300. Look at how small the valve pocket is compared to the total bore area. On this motor a 72mm piston was working with these tiny valves to fill the volume it swept, a recipe for low power! Jack I simply cannot wait to get your motor apart and back together with the serious Malossi kit parts! This head is dead stock and has about 8k miles on it.

[Micah / AF1 Racing]

This head I decided to fix, deck and see what sort of power gains one might be able to make with the stock head and cam since the obvious power limitation of the motor is the port size/shape and valve area.

I think it came out pretty nice. No, it is far from a Malossi head but the idea for the build of this motor was "parts bin" and "cheap" so a modded stock head was used along with a piston/cylinder kit from an Aprilia SportCity 250cc which offer higher compression.

The last pic is just food for thought you power hungry Vespisti!

[jrflanne]

So, I wonder what kinds of stuff you can do to one of those motors before the bottom end takes a shit?

[Micah / AF1 Racing]

We shall see I guess? The rods are very two stroke like, needle bearings on the big end. I bet Carillo could make something truly sick in forged steel of any strength required. Bottom end looks tough.

[jrflanne]

You are out to build the Vespa from hell, aren't you. Turbo, nitrous, it's madness! Fuckit, i'm in. Can't wait for the doggone head to arrive. In the meantime, I think I'll lurk Modern Vespa.com and see what those fuckers are up to.

[Micah / AF1 Racing]

I just want to make them live, reliably, up to their potential. They are so satisfying to work on, on superbikes gaining 20-40% in power is neigh impossible but on scooters and cruisers there is a sime roadmap to progress. For me, seeing and feeling real results are the fun parts. Making a Vespa even more fun To ride is a big plus too!

[slowmike]

I would be worried about unnaturally short belt life with that much power. But if it works, I do love my little vespa....

[jrflanne]

If the powertrain becomes the weak link, strengthen it. They run 300+hp snowmobiles on belts so it can be done.

[jrflanne]

Glory be! The head has arrived in the states, to be shipped to AF1 today. Of course, I'm going on a vacation so a bit further delay.

One thing is I have the Bitubo front suspension dialed in. It is still pretty stiff but 1000% better than the crap/shot stocker. Definitely worth the money for those who might want to upgrade their scooter.

[Micah / AF1 Racing]

Awesome news Jack! Since you are going on vacation I will just install all that stuff on my new Vespa! Glad to hear the shocks make it handle so much better, cannot wait to try out your scooter on the road with your new suspenders. The extra power will be mega-bitchin' too!

As far as belt life goes I figure it is sort of an exponential relationship. If you double the power the belt probably lasts about 25% as long. We shall see for something wicked this way comes!