Modern Vespa

Hi guys. I live in Indonesia, and I recently got a 183cc Malossi 183cc kit and an Aracer Mini X installed, on which I monitor the engine temp.

It's usually around 30 degrees here; today, I was driving on the highway, and I noticed the engine was going all the way up to 120 Celcius. (The mechanic told me a maximum of 115 degrees for these kits)

He recommended I remove my DB killer, which is not in my best interest, as it will become noticeably louder.

As an air-cooled Vespa sprint, I wanted to ask what could be done.

Setup:

- Arrow exhaust + 3" pipe
- Malossi 183cc + Aracer (Fully dyno tuned to 14 hp)
- Ported header
- Polini Hi-Speed vario (+12,5g rollers)
- Drilled flywheel
- Polini Airfilter

Installing an Air scoop could also be possible, but I wonder if these have an effect.

I really appreciate any help you can provide.

Sounds very lean. What was done to richen the fuel mix in response to the mods?

pull the plug and put up a pic of it

what was the temperature it operated at before you put all the stuff on it? You're talking about a minor difference between what the mechanic says it should be and what it is. But you need to know the temperature it operated at before you did all the work.

What's the air fuel ratio you saw when you put it on the dyno? What sort of air filter? What's a ported header?

If the list is everything you've done to the bike, you might want to look at a set of rear end gears to lower the rpms at the speeds you now ride. And 15-50 synthetic motor oil is a must with a setup like this.

Well, the Aracer has an auto-tuning program. Basically, the computer does it, and then I dynoed it for 4-6 runs. Thats all I know

There you go:

I unfortunately don't know too much about the capability of this Aracer computer (yet), and I don't even think it's possible to see the engine temp without this computer (which is connected to an app on my iPhone), so I couldn't give an answer of previous air to fuel mix or engine temp.

You mention that 15-50 synthetic oil is a must; I've been recommended Motul 5w-40 Power Le.

I don't love the look of that plug, but it's not too awful. how's it look further on the insulator? which plug is that? it's obviously not a projected tip.

I'd be running 15-50 in that environment with that setup.

where is the temp sensor located?
what do you mean by "drilled flywheel"?
have you modified any of the stock forced air induction cooling set up?

Due to the engine running hot yesterday, he advised me to set the engine timing to -3 in the Aracer settings, which should make the engine less hot; that might be the reason.

Would you recommend this type of oil? (Motul 3100 Gold 4T 15W50 0.8L)

https://www.tokopedia.com/partsuniverse/oli-motul-3100-gold-4t-15w50-0-8l-oli-motor-original

From my understanding, they make holes in the flywheel to give it faster acceleration. (instead of buying Polini, for example.

retarding the timing generally results in a hotter running engine.

partially from hotter exhaust temperatures and partially from needing additional fuel to maintain the same power level.

anything is worth a shot, I guess.

I'll give the air scoop a go and update everyone on the temperature difference afterward.

The mechanic just told me the compression is set at 11.4:1, and he would like to try to lower it to 10.8, so I might do that when it's time for an oil change in 500 km.

How?

base gasket, most likely

Now would be a good time for an octane thread.

you have caused me to make my displeased face.

With all the mods that you have done, and the lack of sensors that would provide the ECU the data needed to adjust, I would not trust any "automatic tuning". Also, I could not find any Aracer that was compatible with the 2023 iGet. Support stops at 2020.

So having suggested you don't go bigger that 62mm (171cc) which would have could have been 11.2 compression and having talked to Timmy from Indonesia (30C+), you went 63mm and 11.4 and it doesn't work properly.

Is this about right?

From the looks of that plug, you're probably in the 14.7-15.5 to one ratio range, or even higher.
You need to figure out what the air fuel ratio is when you are riding, and adjust the box so it's in the high twelves, low 13s to one ratio. Malossi and a lot of other companies, make devices that give you real time information about the air fuel ratio. This will cool the engine down.
The downside to air cooled big bore kits is that they remove a lot of the cooling material to make room for the bigger piston, so you need to set them up right or you will find parts of your piston where the electrode from the spark plug used to be.
The Malossi kit is 11.15/1 compression, so I'm not sure what your mechanic did to boost it to 11.4/1, but it's likely not something that can be undone. 62mm or 63mm bore isn't going to make as much difference as the quality of the components, and you're fine there.
If you and the mechanic have done anything to the airbox besides putting an aftermarket filter in the stock box, undo that. More air is not your friend until you get the rest of this build sorted.

I have a sneaking suspicion that the factory forced air cooling system has been modified in some way for looks.

that in combination with the higher compression and likely lean condition, again due to some other type of modification is pushing cylinder temps up.

get the mix fat, stabilize the temp and then see where you can make an improvement. it's ragged edge now, and at the point of not if but when things are gonna go brown and round on you.

Hey Mike! Thanks for the help last time!

I spoke with a lot of people about this! Timmy recommended this Malossi 183cc kit to me, and everyone says it's the most durable kit you can get.

Balitalia wouldn't install anything for me because, due to company policy, all the parts had to be ordered through them. Unfortunately, the Aracer ECU was out of stock with their supplier until March.

I ended up ordering myself from Tokopedia, and getting it installed at Zanket Moto in Ubud (Popular guy for tuning; search on YT)

Zanket told me that 11.4 should be the most safe for daily use.

For now, I switched the spark ignition back to 0 from -3, and looked at the spark plug again this morning.

The engine is still running quite warm (around 110 Celsius); I ordered an Airscoop, which I will install later this week.

Zanket Moto persists that I have to remove my dB killer and says that is the cause of overheating and the spark plug.

What is your take on that?

It's called an Aracer mini x; it supports the IGET. Anyway, the tuner hasn't mentioned anything about combability.

I have faith he would have told me if this device isn't compatible.

Hello mate! Thanks for the thorough explanation. Im still a beginner in this field.

Besides putting the Polini filter inside, the box has remained the same.

I just recorded a ride around the neighborhood where I was "riding it as I stole it."

The temperature is stable around 90 degrees Celcius when I'm on the gas, with much variation on the throttle.

It is mainly a heat issue when I'm in traffic, and traffic in Canggu can be terrible (bonus: the heat is 30-35 degrees).

You see in the video "AFR_WBO2", I'm pretty sure that air-fuel ratio, but! Does that have to be multiplied by something?

I just looked at the video from Aracer themselves:

https://www.youtube.com/watch?v=uFTIRXJSGOU

Link to the recording of the ride
https://screencasts.lucasnygaard.com/recordings/J7lq6shfrJ04RvuMm2eL

Many thank you for ALL of your help!

Does Aracer alter the idle speed? Needs to be higher than 1,800 ± 50 rpm. To keep the cooling air flowing.

A GY6 scoop. I stuck one on my Honda.


I don't notice any significant difference by the "seat of the pants' method. I also installed an oil cooler.

You better hope it isn't.

Let me check! I think its around 18-1900 rpm in idle now.

Hmm, interesting; I ordered everything; gonna test and see through the app what it does.

Last thing I want to do is a oil cooler