Tuning advice for Aprilia SR 125 2T

Just need to borrow the brains of all you tuning magicians out there for a few minutes.
I've never tuned a scooter before and have no previous experience with mechanics (apart from downhill mountain bike repair/servicing) so tuning is a bit like another language to me. Lol
So to cut to the point. I've got a Aprilia SR 125 2 stroke.
Everything on the scooter is original meaning it's had no upgrades. Everything is factory standard.
If I wanted to convert said scooter into a 172cc Malossi what do I need.?
I know I need air filter, piston kit, exhaust, carb, rollers.
I just don't know sizes and what parts are compatible with what if that makes sense.
If someone could take the time to do me a step by step of what they would do themselves it would be much appreciated.!!
Thanks in advance for any reply's

Also. How do people take the engine shroud off and polish up the engine casing?
Wouldn't the removal of the engine shroud effect engine cooling etc.?

 

Polishing i can help here.

alloy will oxidize , that oxidizing coating left will protect the alloy under it. when you polish alloy ( most scooter engines will be alloy) you are removing that oxidizing layer and buffing the alloy to a shine, problem is right away the alloy starts to oxidize again , there really is no way to stop it unless you spray the shiney engine with a clearcoat thats heat proof.

you can however stay ontop of the oxidizing by constantly re-polishing the engine, the problem is that can take a lotta hours and you need to get into every nook and cranny.

to polish you will use a brass brush or likes to remove the oxidizing layer, then you will use a polishing agent, like a metal finishing compound on a cotton wheel, this is used to cut away a very fine layer and give you that shine.
amatuer wise you can make mistakes by polishing one spot to much, heat build up and your area starts to blue with heat, then you have to start again with the cutting/finishing compound. if you have a dremmel you sometimes get a little pot of polish compound with them, pop on a cotton pad to the screw awl, set your speed to around 2-3 and run the wheel up touch it lightly onto the compound to coat the pad.

now grab something you wish to shine up , a dirty coin works well here something like a 2p or a dirty 50p , DO NOT PRESS HARD, just let the weight of the tool rest on the coin and slowly shine the coin, you will want to stop now and again to allow the coin to cool down ( friction produces heat and its gonna get darn hot to, so you learn what happens to a larger chunk of metal like a motor case ) , once your done you should notice the cotton buff pad is now a dirty'ish black, thats all the crud you have cut off the coin ie dirt and a very fine layer of metal. and you should end up with a nice shiney coin in the end.

polishing takes time and a lot of practice work , but once you get something mirror like finished you will not be able to stop and will hunt for things to polish up. there are differnet compounds for different metals and finishes to, red rouge is a common finishing compound used , when you take your wedding ring to be polished it tends to be done with red rouge compound

removing shroud is not ideal as its aiding in the cooling of the engine head. you would normaly polish the likes of the side casing and the crank casing leaving the cylinder/head and the shroud to do its job fully. there are some produces that delay the re-oxidizing of alloy but most would just repolish or use a product like carnuba wax to help protect the finished work.

 

thanks for that. It's brilliant post!
Great for future reference for anyone who visits the forum in the future too.
The only reason I ask is because every 2T scooter I see that's had a 172 conversion done, has had the engine shroud and box air filter removed and the casing is polished.
Just wanted to know if that's something you do yourself or if it's better getting it done professionally.
You've definitely cleared it up for me and to be honest it sounds like far too much work just for a bit of shine. Lol
I'll give the polished engine casing a miss but the 172cc conversion is still a maybe.
Thanks for the reply!

 

Tuning is how far do you want to go and how much do you want to spend? A 172cc top end will work great on the std upjetted carb, std exhuast. This set up will want to wheelie off the throttle but will suffer top end, so a 180 gear kit will tame it and give a little more top speed. I have a typhoon with this set up and it's quiet, loads of torque with a good top speed ! If your young and daft (I was once) then a PM 52 pipe, race crank, 25mm carb would set you back possibly £1000 ! It's whatever you want it to be. Also is it an everyday scooter or toy?
HAPPY NEW YEAR!!

 

Just planning on making something up that is fast but not stupid. I don't want to have constant maintenance so a setup that is still good for getting around would be what I'm aiming for, I don't mind general maintenance costs.
another 10mph on top of the 65 I get already would be more than enough.
Thanks for reply too. Great advice.

 

Oh and happy new year!!

 

A 172 barrel and gear kit then, good for every day use. p.s, it will do bugger all to the gallon with a 172 kit!

 

So I need a full 172cc piston and cylinder kit and a 180cc gear ratio kit.
Would I not need to upgrade the carburettor, air filter or exhaust??

 

It will run fine on the std carb/exhuast etc, just upjet to 90/92 main jet and make sure the oil pump is a tad on the rich side.

 

100% going to go for it as soon as I've got some money to spend.
I'm still due the payment from my other scooter that got written off so as soon as that money comes through I'll be online purchasing a few parts.
I'm looking forward to it.

 

Highly unlikely that the police would be able to determine wether the scoot had been upgraded or not without a full inspection of the bike.
I understand what you're saying but most 2T scooters you see around now days have been upgraded some way or another.
In the event of an accident my voluntary excess should cover any damage to third party vehicles.