Expansion chamber exhaust

[goodkat]

My AF24 exhaust is shot, I am tempted to get one expansion chamber type exhaust. The engine is the same as on Dio AF18/25/27/28.

Current specs: new everything as on standard (50cc).

What exhaust should I get for it? In the future I'm going to push the cc to 72 or 80, mild, nothing extreme.

I am located in Europe. Also, if there is anyone in Europe selling one that fits, I am interested.

[190mech]

If youve got stock port timing,squish,etc there is no use in getting an expansion chamber,start modding it then yeah,its a needed item for sure..Sorry no brands were given as a pipe design is very specific to what the build is...

[ThaiGyro]

My Honda has similar, but not the same top end...and what 190mech says...If you are modifying it as a 50cc, there are few options, but some should be available in Europe.

If you are going to build a bigger displacement engine, you will need a chamber designed for that overall volume.

Sorry kat, no easy answer. However, you can make a specific plan...for example: You want a 70cc that can reach 10,500 rpm. OKAY! Make a pipe that gets close. Or, buy one that is advertised as such.

When you go bigger, nearly everything must be changed or modified or tuned. Change = money spend; modify = time and effort, maybe some money; tuned is normally just time, but toss in some CVT tuning and more money, surely.

Sorry, the answer is maybe not what you hoped for. The good news is that 1) YOU ASKED FIRST; 2) There are people here that have your engine, thus can give better detail/opinions.

[goodkat]

Thank you both for your answer, it really helps me to narrow my research and get an idea about what I want to do.

I was digging on internet and found about Tecnigas. They have a model that seems to be advertised for 50cc-70cc cylinders.

First of all it must feed the need of an exhaust since I got none at this moment. The performance is on the 2nd level for me right now.

Here it is the model I'm talking about (I hope it's ok if I put the link) : www.racing-planet.de/exhaust-tecnigas-next-r-for-kymco-sym-vertical-p-303-1.html

[Zino]

I can speak for the next r on a yamaha it is a mild upgrade it does work on a 50 cc stock engine and also a sport 70cc.
The port timings on the standard pipe starts pulling at 5000 rpms dies out at 8500 rpms and the next r power starts at 7000 rpms and dies out around 9300 rpms.

That required a total reset of the cvt
So you have the right take off so you will need to go up a tension on the clutch springs
You will know you are right if when you crack the throttle and you move right away if you roll slow for a few feet and the take off the clutch springs need to be harder tension .

You also will need light weights for your variator.
I would expect for you to buy a few sizes smaller and go one notch progressively lighter and make notes on how each weight feels for acceleration and make note of your top speed go with the weight that gets you highest top speed and your butt dyno likes best for acceleration.

[goodkat]

Thank you @zino18, valuable info you got me. So, Next R should be a good budget to performance mild upgrade that shoul fit my requirements.

As I said, I'm not looking to get a huge amount of performance out of my scoot, at least not at this moment.

I have everything standard so I can have a bottom line where I can start from the mild tuning.

This year I want to have it as a commuter until I finish my other bike. After that, will change the crank, cylinder, clutch and variator with something better than standard.

[ThaiGyro]

Good kat! 190mech and Zino have much more scoot-poot than me. I am a 125cc to OMG 750cc 2T guy, but the dynamics are the same or close.

You will find quite a lot of learning, but fun, in getting your pipe to bleed well. Do the engine tuning, slooooowly. I recommend head temp and rpm gauges, minimum. Cheap and informative. Record both at a few minute gaps. When stable, try some throttle glips. If not crisp and clean...Come back here.

Set your ignition to the factory spec. As near perfect as you can. Do the pipe and fire off, but warm up...do not go full crazy. Test carefully, and stop at any thing you cannot comprehend. It is not dumb...it is smart.

If you get close on tuning the carb and ignition...go to the CVT. You would be surprised at the difference that near perfect is versus stock.

[Zino]

Thaigyro makes some good points about rpm and temp gauges .
I have both on all my scoots help a ton with health and tuning .

One other thing you need with a expansion pipe is larger jets in your carb .
To make sure you are not lean at the higher rpms of your free flowing pipe .
A good go to is grab a jet 10 % larger than your current jet and a couple in between your current and that one .

Run down the road wide open with the largest jet and take notes of how it feels and top speed .
Go progressively smaller on the jets ,Ideally you will feel 2 close to the same with similar top speed Take the one with the bigger Jet.

[repherence2]

From what i have read on another forum, the Arrow pipe is said to be a good pipe. Most will use it on 70cc bores. From what i have read, people that have tried them on their 50cc set up liked it. It's quite pricey at $300. However, it's a good pipe if you want to upgrade to a big bore kit later. Gianelli makes the same pipe too. I have an Arrow and i have seen a chrome Gianelli at a shop, those pipes are identical.

Not many chamber pipes to choose from now for the vertical Honda engines.

There was a time when scooterswapshop had a Yasuni c16, 2fast4race pipe, and a Polini Corsa chamber pipe...those are not available now.

PG (Phongeer) short pipe might suit your wants. Do not get the PG long for your 50cc. From what i have read, a 50cc bore does not have enough volume to pressurize the PG long to get it "on pipe".

Look into the Arrow/Gianelli if you are in Europe.

[Zino]

here is apipe that worked real well for a honda build and a lot of the dio guys swear by them .
www.partsforscooters.com/190-50-Honda-Dio-Exhaust-Unfinished

here is a thread where we are talking about various honda builds .
49ccscoot.proboards.com/thread/26076/girlfriend-dragged-out-dumpster-literally

I am not a honda guy myself but I know how to build up a 2 stroke .
A buddy got a honda elite with the vertical motor for nothing and we threw on a polini corsa a v8 pipe took off like a rocket ,We gps at 58 mph
We did have up gears in there not sure the size .
If we just did the pipe and corsa kit breaking 50 would have been easy enough .

[goodkat]

You guys rock!!

Let's take it step by step:

repherence2 - being located in Europe, sometimes sucks, sometimes rocks. Mainly we are sticking to what is produced here or what is imported w/o taxes because otherwise, the shipping from Taiwan, US and Japan is rocketing sky-high.

I need to find out the model for the Arrow / Gianelli exhaust you are talking about. Tecnigas is affordable and also there were lots of Philiphine guys that were swearing for this pipe.

Thank you so much for all the support! You guys are awesome!!


@zino18 To be honest, If I would buy a scooter again, I would take something made in Italy, there are lots of parts for them around here. There are parts for Honda as well but not so many aftermarket parts available here.

[ThaiGyro]

Haha! What zino linked and repherence said...is the same pipe! The Phongeer shorty. I thinbk ugly, but on near stockers works very well. So you know, not Chinese, but from Taiwan. NOT the same...ask me if curious. Taiwan rocks!

Not a top end pipe, but easy to tune to... just looks like elephantitus of the sack...

[Zino]

Sorry did not pick up you being in Europe .
I spent some time in Italy and France .
Scooter Heaven as far as I was concerned they were everywhere .
I spent some time in Bologna Italy The home of Malossi parts .

Tecnigas pipes are good quality pipes .

[harleyracer59]

I have tried as bought and cut up a few of those 80$ fleebay dio chambers. ive even turned one into a side bleed. that added 500 rpm to the beginning and the end of the powerband for some reason. idk. ill take it though. they have a good performance upgrade to a 50cc and a sport cylinder 70cc. fleabay ships world wide. might be an option to check out. I like them and theyre cheap enough to cut up and experiment with. and they are thick enough gauge to last a few 100 miles. thought id throw out that suggestion.

[ThaiGyro]

What Harley refers to as "side bleed", is my stock. My trade. Bread and butter. I am now 63, but have been working "Center bleed", side or whatever, since 1975-ish.

They can be better balanced, if you get close the bleed port sweet spot. Even if off, they will self tune...but at a cost in rpm, torque, throttle response...You might not know, but it is just internal pipe flow dynamics.
When you pay crazy money for a big name pipe? Flow dynamics! You tune to it. More power? More sound? Better "feel"? They are all more quiet, due to internal wave balancing/neutering.

We did a dyno series on my '99 Mazda Miata. 1.8 liter, stock internals, except a programmable ECU. We did OEM exhaust, We did "sport headers". We put on a "Spec Miata" competition system to run SCCA. The results? Sound, primarily. So you know, the "spec Miata" headers, were IMO, sponsor money...lost 5 hp on the dyno to OEM stock. I did some flow research, and installed an OEM manifold header from a 2001 on my 1999. Plus 11.6 HP!

You must get the poo-gas out quickly and let it goooooo!
So play with your pipe by tuning to it...have fun!