Modern Vespa

This bike has become my go-to ride for quick runarounds. It's fun to ride and it's loud when I get in the throttle. If I drive slowly (just barely beating cars off lights) it's only a bit louder than before but twist the throttle and the exhaust makes itself known. It also has a delicious backfire that I rather like.

November is getting closer and that's when the engine work can get started. Almost tempted to not change anything as it's so fast already...but I MUST see what this head will do.

Malossi head sent off to be machined today. As soon as it's back this project can move forward to the next step.

what machining is being done?

I followed the thread over on the Aprilia forum where Micah from AF1 in Austin took a Malossi 4v head and opened it up to flow even more. I asked him to do the same work for me.

This projects been dormant a while Had a few hours today so decided today was as good as any to begin.

And the motor as is prior to taking off the old cylinder and head.

Polini 294cc or Malossi 282 cc?

Malossi 269. It's a 250. Got a lot more done tonight. One of the dowels is stuck in the cylinder so I'll be ordering that and a few other parts I'll need to get this thing back together. So far so good. Fun work after my day job.

What scissor lift are you using under the frame? It's a lot more compact than mine.

Extreme Max 5001.5044 5001.5044... https://www.amazon.com/dp/B0196PAZ1S?ref=ppx_pop_mob_ap_share

Taking my time as I wait for my parts to get here. Dowel supposed to arrive Saturday. It's small, skinny, and I gave up trying to pull it out of the old cylinder. It's the only part that by messing up has halted progress. Fits between the cylinder and the block so I can't even get that first piece on. In the meantime here are all the small parts from the head and a couple other places.

Killer. There is something about a quick scooter that is satisfying in many ways that cant be replicated. I think its partially "underdog scenario" mixed with the fact that it's more fun to operate a slower thing fast than a fast thing slow. I have scoots and bikes, my most proficient bike is an RSV4 which see's mostly track service; it can be operated on the road but when it comes time to grab something and go, the decision is 90% scoot.

Full agreement there. These bikes are already super quick off the line. I can't wait to see how much quicker this one becomes.

While I wait for my parts I've turned to figuring out where to mount my adjustable fuel pressure regulator to get my fp up from 2.5 to 3.5 bar. I want plumb it in and have realized that fuel injection line is different from regular fuel line and I don't know what size line to buy nor can I get the fittings I need for the fpr. Anyone know the size of the fuel delivery and return lines on a GTS250?

Thanks. Ordered one.

Good buy! You'll be happy with that lift.

Ok so for the first time ever both Amazon and FedEx came early on a Saturday. Delivered the dowel I needed and my assembly lube. $7.49 at the local auto parts vs $5.99 on Prime meant I'd wait the 2 days and save $1.50.

Put in the dowel and assembled the cylinder and piston.

Next I put on the head and reinstalled the cam and rocker arms.

Spent extra time trying to get the timing chain perfectly aligned. Here's what the gear ended up looking like.

And the view from the sight hole to see the mark on the crank.

We have success 8)

Did everything I could to get this sucker back together before sunset. Still have to go back and finish up some odd and ends but I couldn't go to sleep tonight without firing it up today. Turned the key and in under 2 seconds it fired up. Took a 3-4 mile joyride and now it's back in the garage. I'm sure there will be bugs to work out but I'm pleased with where things are. A fun bike to ride is suddenly a lot more fun.

Great work on this GTS. I like the subtle aesthetic bits you've selected.

The motor work is exciting as well. I'm guessing the headwork done on the Malossi V4 head was a polish and port job...should help a bit.

I have the same PM Tuning exhaust on my GTS and my reaction to it is the same as yours...rather quiet unless you crack the throttle open aggessively and the small backfire when closing the throttle and decelerating is a bit of fun.

Thanks CrazyCarl
This was a lot of fun. Yeah it was some light port work, taking what Malossi did and making it better.

You hit the nail on the head about the PM exhaust and the deceleration popping. I even throttle up and coast to hear the tone it makes as it coasts down. Great conversation starter on group rides too.

Did you put the little o-rings around the studs before you put the head on? I'm just wondering. Just had to pull my head a second time 'cause I missed that step. Fortunately, I didn't start the engine. I bled a bunch of coolant into the oil pan and on the ground overnight, so I knew something was wrong.

Yes I put on the o-rings. They actually came with the new head in the bag of gaskets.

When you put them on make sure you cut a piece of plastic about 2X2" to cover the threads. Grease the o-rings up and they'll slip right over the plastic and threads onto the smooth part of the studs.

I ordered my head and cylinder base gaskets ala carte, and didn't think to replace the o-rings, even though they were 13 years old and clearly were dried out and cut up from pulling the head and cylinder.

I saw the plastic bag trick on one of Robot's videos when I was trying to figure out what I did wrong.

Nice looking project. I also just used the lift you recommended. Worked like a charm.

Old thread, but it's mine so I'll keep it going. Bikes been parked for a while ever since my garage fiasco when this one ran over me and caused my 300 to fall off the platform it was on. Whole other story, told somewhere on MV.
Anyhoo, now that I've got my '17 300 back on the road my sights have settled on this one. It's got the Malossi cylinder and head and for a while was my favorite to ride.
Put a new battery in and tried to start her up. No sound from the fuel pump. Turned the key at least 50 times, beat on the gas tank, nothing but clicks, fuel pump is DOA.

Have a new fuel pump on the way so took out the tank tonight. Couldn't believe what I found.


Thick black ooz in the tank

Horrible nasty thick tar goop in the tank

Fuel pump looks like it's been through hell

Dumped in a few cups of Superclean to degrease and after some work with a toothbrush and a long wooden skewer, followed up with some scraping with a flathead screwdriver I had it clean


This stuff was thick!

Self explanatory

Clean as I can get it

Tank will dry out now. It's Wednesday, new pump should arrive by Friday and we'll see where that gets me. I'm ready to get this beast back on the road. This is my fastest Vespa with the malossi head and PM68 ear popping exhaust
Future plans for this bike is I want to get away from the red. I want a color that matches it's sound and power, like a bright yellow or orange. Like a badass Vette or Lamborghini.
It's got a new dent from its garage mishap and I want to fix all of that. Hard to believe it's been almost 4 years since I bought this thing. Got my eyes on another 300, a 2012 that I want to make into a second beast.

After trying to resurrect the old pump I gave up and bought a new one. Reassembled everything and it works like a charm. Also put the dB killer back into the PM 68. Purring like a kitten but roars when it gets gas. This setup will be more pleasant when motoring around.

Hey there! Love your 250. I recently inherited one almost identical, and am looking to start on some beginner mods. Could I ask where you got the black trim? I'm having trouble as a beginner finding parts for that year.

I'd love to put some black bars on it as well but don't know where to look, or if any even exist! Maybe I'd need to get em powder coated I don't know.

Keep reading on this forum and you'll quickly figure out where to get all the things you like. ScooterPartsCo and Scooterwest are two really good places to start. When I'm shopping I use both as well as SIP but they're across the pond and the shipping can get expensive but they have LOTS of stuff.

You're gonna love your new bike.