Thread: PGO big max 50 project

PGO big max 50 project

Hello all I’ve been a member for a while on the forums but never had the time to really post anything yet, so here’s my post for my scooter hope youall like it.

For the moment I’m not aiming for a high standard scoot just enough for me to do my everyday errands hauling my butt to work and back and maybe sprint a few scoot fans along the road aswell.

Here’s some pix of my scooter before I really went into the tuning thing, the original colour was orange and it was a beaten up scoot (I bout it while the old owener had a sever accident with it and twisted the from fork into a rooted tree, also the frame suffered the handlebars were touching the seat.) but I don’t have pics of it in that shape this is when I just restored the scoot, took me about a months work non stop of torsioning the frame back to shape, refibering the front plasticwork and getting the engine back to working condition. the investment wasn’t that high as the only things I had to buy were the things I couldn’t create myself (the blue silencer pipe was the only thing I really bought).

here is the setup I made to it (please don’t laugh these parts were hell reliable on the scoot)

engine block: stock

pipe: direct out (yeah in case you ask it runs HOT, but makes a nice deep noise, I loved it at the time but it was ok for a normal pipe)

cylinder: kit 70 fonte KOSO X47′ AC tough sturdy steelcast kit bored to 47mm no port work whatsoever same as an original 40mm but just biger bore that’s all

carburetor: HM (17) with 80 mainjet

admission pipe: stock

air filter: KOSO Performance Air

clutch: tojours du KOSO X-gear (I have no idea if it’s even a real brand koso but the pickup is pretty good looks like a TNT standard clutch)

vario: toujours du KOSO Speed CAM

belt: mitsubishi bando VS belt 738

visual tuning:

dual xenon 100w lights I love these lights blinds out the oncomming traffic completely, I had to rewire a capacitor on the line to keep the battery from dying out, next I used an 12volt battery from my UPS system and it was perfect, handles way better than the original cheap 3amp scoot batteries.

painted her blue and matte black (pretty nice at the time)

performance wise the bike was pretty reactive but it never went over the 58kmh line, I didn’t mind much during the time since nothing was really tuned on the bike and I was just really happy it even ran at all after what the previous owner did to it.

after which I wanted to get a little more speed out of her, so I deciced to weld meself a pipe, I was searching on the net for info and such on how to nicely calculate the pipe length and expansion, I found a nice little app that I loved it was called cone3d you could draw one shapes/angle/size/taper and then print it out afterwards. also I tossed the KOSO x47 cylinder into by box of parts and bought two complete cylinders plus one already used yamaha 3KJ 50cc steel cylinders, I went over to various garage sales and found a broken vaccum cleaner rotor and some shaft wire (these were my tools for porting the steel cast cylinders), I was a noob and still am so I didn’t want to do much to the cylinder in fear of ending up with junk. I began by opening up the exhaust port of the cylinders (some were half cirlces since they are catalysed) I made them nice and round and also opend the exhaust by 2mm (I was scared as hell about thism since I had no previous experience with this porting thing before), I cleaned up the whole cylinder and made sure there was no bedris, took out some fine grit 800 paper and sanded them to a polished finish. hooked it up to the bike, went back to finish the pipe. once done I tested her up for a test run, I was speechless it worked I didn’t care even if it gained 1 or 2 kmh more but it worked, I rode the cylinder in for a solid month and then did a test WOT on a straight runway I got a spanking

67-70kmh out of her, but then something bad happend, I heard a bziiiiiiiiiiiip noise and then the whole bike locked up in the engine, I was scared I was sweating all over, I held the throttle wide open to help cool it off, I pulled the bike over. poped out the spark and I saw it was chalky white, real white. I was runing to lean. I pushed the bike home since I didn’t want to turn it on till I got some new mainjets for the carb.

Here is how she looked with the homeade pipe and slightly ported cylinder.

– bought a big sticker and put it on the front of the bike.

– also I loved the way the homemade pipe looked even the silencer was made of inox metal. it was pretty heavy for a pipe.

– polished my carter took me a whole night to scratch of the nasty black paint I had no paint thinners just my bare hand and sanding paper started with 180grit and moved up till I was at 1000 grit, then I just zexed the carter to give it a slight mirror shine.

– bout me some new shocks NCY gas rear shock with a red extender.

as I got more and more into how the scooter functions I was more addicted to how much these 2strokers can be so powerful. next up I bought

– hebo adjustable clutch. poped in the blue springs that came with it.

– I cut my rear bell so it became lighter and not heat up as much.

– designed a new pipe and bought a new blue silencer to go with it

– bought me a bigger carb mukinu 19 with 87.5 mainjet

– got me a TNT downhill bar and rod carbon look

– painted the bike white this time around ( I love it plain white)

– made me a new seat cover patterned after a BCD model I saw on the net

– drilled holes in my Koso vario to make it lighter and the wholes act as air vents to cool it down

– bought some DR pulley fadeless rollers 3.5 grams

– stared to go tune the KOSO x47 cylinder I used before, I widened the exhaust by 4mm and started to smooth out the bulky bits on the gills (boost ports I think they are called, we just tag them as gills)

– bought me a new spark cable from NGK the red rubber type

– bougt a ton of electrical wires since I had to redo the whole electrical part of the scootm, I had a short that burned my wires like cheese.

– bought me a new air filter, this time a Polini big blue evolution filter.

-back panel remodeled with fiber custom fit

-the tail light mono style

-front panel (also made external fixtures for the front panel bolted on )

-back panel redone to have the fin and mono tail light (always loved monospheric tail lights )

-electric wiring all changed

-no blinkers at all (never used/needed them anyhow)

-carter case cut and polished and added small filter on clutch side (not it pic will be posted later )

-starter switch ( race style)

-custom cut stickers (reflective)

-Stator (redone bobin core after it burned out) advanced timings by 2mm

-borred stock admisison pipe to 20mm

-TNT racing blue boost bottle

-TNT digital speedo (Koso model under the name of TNT really)

-NGK R 8 rating plug

-yellow Bitubo rear shock

-ducati ignition coil

after all of this was over with I went and tested the bike again. this time I got a new personal speed record

96-100(going from 0 to 68kmh was realy quick, then the scoot lags at 70

76 then it goes really fast to 80 and then takes some insane time to reach 100) I have flat spots in the scoot I can’t figure out where or what is causing it. I touched the vario weights and tuned the clutch somehow it was better but then when I get to 70 it makes a blurging sound (as if it’s running too rich), here’s how she looks with the above setup.

after tuning it out some more over the past few months I got her to go 115kmh for a very short period, she runs really hot and I have a feeling it’s the spark plug the bottleneck, the rest was still ok.

after some silence I decided to go for aluminum AC so I went over and ordered me some new parts (one of my biggest investments ever for the scoot thus far). I didn’t want a true race scooter, since I wouldn’t know how it worked to get a big increas in speed, I’m a real bookworm and I love to read up on how a certain things works the way it does, and also I would like to do the tuning myself and see how far I can push my limits and the bikes limits even if it’s not a world record or a beasty system I still ove the little performance I can squeeze out of it. here are the parts I ordered from a german scoot parts site.

– (5x) Hebo manston NG AC cylinders (manston replica it’s called in some places)

– (4x) Hebo piston rings

– (3x) complete Hebo gasket set

– (2x) BGM pro EVO racing crank (one is already mounted in the engine)

– (2x) sets of SSC bearrings set

– (4x) NGK BR9HS sparks

– (1x) Yasuni C20 pipe (already mounted on the scoot)

– (1x) BGM pro 21mm carb

– (1x) set of 4 carb main jets

– (1x) Polini carbon fiber sheets for reed (0.30mm blue)

– (1x) Doppler reverse intake filter

– (1x) Polini speed control

– (1x) Polini air speed varioplate

– (2x) sets of different weights for the vario

– (1x) Malossi X kevlar belt

– (1x) BGM Blade bell for clutch

– (1x) Keisler Subframe for Minareli horizontal engines

– (1x) Tassinari Quick action throttle (mighty fine looking )

– (1x) vredestein 130x90x10 tyre (so sexy )

– (2x) shock mounts

– (2x) BGM yellow fuel hose

– (1x) BGM circlips pliers

– (4x) Variomatik grease

– (1x) HQ copper grease

– (2x) Hight temp laquer (for the pipe and some other engine casings)

I AM SO HAPPY for these parts, I heard the manston replicas are the same as the real manstons xcept for the smaller gills and exhaust.

also placed an order for a dremel 400 kit and a slew of EZ lock head to go with it. since my vaccuum cleaner engine isn’t for precious kits it was solely meant to learn the functions of a 2stroker and where it can take me.

below are pictures of my bike now the paint needs to be redone completely but I’m still working on it, I prefer to tune the engine out then paint later.

I had to match the case to the new cylinder and I cleaned up as much as I could around all the areas I have touched, I hadn’t touched the cylinder yet since I’m a total new guy to sinic aluminum. The performance though i can clearly see it’s total (now I kinda get the feel of how a real pure drag bred engine might be ). I hope you all enjoy, sorry it’s a loooong post .

– also I would very much appreciate if someone can advise me on how to tune the aluminum cylinder, I am so afraid of breaking the Sinic on the cylinder, plus what to do first to gain a little performance out of the cylinder without sacrificing too much reliability?.

– what dremel heads to use to make sure the porting doesn’t go wrong? (what type of heads and waht sizes).


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