Want to up my Vino to 70CC

[jonnyrocket]

Thank you so much!

[jonnyrocket]

I did it! 3 weeks later and a lot of money cuz I had to buy and learn to weld (pipe.)
It's all good, except now I have to learn to tune it. It sounds a little pingy and I am guessing here it's lean. I went from a 64 to 70 main jet and didn't touch any needles. I have never been good at tuning, but I did put a chat gauge on it. It idles about 3K and revs on the road to 5800. I am trying to be careful as I am breaking it in. Got a lot of oil in it as scooterpartco recommended.

[aeroxbud]

That's about a 9% increase, so should be fine as it's not an expansion chamber type exhaust.
They can sound a bit like that when new.
Check your plug colour.

[Zino]

What temps are you running at when you zip around town going street light to street light .
Mid to high 200's would be in range. This is the needle mostly
What temps does it level off at on long wide open Under 350 is a upper limit alot of people use .
This tests the main

The street pipes don't need much if any jetting change if the exhaust is bolted up leak free .
you can check this with the scooter running take a wet rag and plug exhaust if it kills quick you are good if it keeps running you have a exhaust leak .

I have run with a 70 to 75 mikuni jets on my vinos
What I needed to do the most is lowering the clip to richen up the needle .

Try lowering the clip one notch if you have similar throttle response as you do now mid throttle go down one more clip .
Take the needle position that feels most responsive from 1/4 to 3/4 throttle if 2 positions feel similar take the richer one .

[jonnyrocket]

I haven't seen it higher than ~270, but I haven't been riding it long at a time. I will try the needle. The 0 - 1/4 throttle is not so good. Flubbers like rich. AT 1/4 to full "feels" good, but yeah, I live in Arizona and don't want it too hot/lean in the summer.

Thanks!

[Zino]

After you get the needle where it feels best you can clean up the 0 to 1/4 throttle part with the idle mixture screw try a 1/4 turn to the left at a time to see what feels the snappiest

To make sure you are on the rich enough end with the idle jet
With the scooter well warmed up
Let it idle and note the idle speed

Blip the throttle. A couple of times
If the rpm rise above normal idle you are too lean
If it comes back to regular idle almost immediately that is good
If it drops below normal rpm and then cleans and raises up to regular idle that is on the rich end

[jonnyrocket]

This is with the clip 1 step from center in the rich direction. It was centered. Goes faster now.

I also covered the exhaust outlet and it kept running. New gasket and the bolts are tight. I found oil though on the bottom of the pipe. Upon closer examination, I found that my patch job of where I accidentally burned through the pipe welding is not sealed all the way. It idles about 300 rpm slower now. Blipping results in quicker drop in RPM after letting go.
I am going to drop the clip to the last notch towards rich and re-evaluate. This is fun!

I also bought an expensive back-saver from Harbor Frt on Saturday... It's definitely a game changer!

[jonnyrocket]

Apr 4, 2024 8:04:38 GMT -5 Zino said:

What temps are you running at when you zip around town going street light to street light .
Mid to high 200's would be in range. This is the needle mostly
What temps does it level off at on long wide open Under 350 is a upper limit alot of people use .
This tests the main

The street pipes don't need much if any jetting change if the exhaust is bolted up leak free .
you can check this with the scooter running take a wet rag and plug exhaust if it kills quick you are good if it keeps running you have a exhaust leak .

I have run with a 70 to 75 mikuni jets on my vinos
What I needed to do the most is lowering the clip to richen up the needle .

Try lowering the clip one notch if you have similar throttle response as you do now mid throttle go down one more clip .
Take the needle position that feels most responsive from 1/4 to 3/4 throttle if 2 positions feel similar take the richer one .

So I put the clip on the richest notch today. It went from idling from 3K to 1400. It also hangs out before lowering the RPM after letting go of the throttle. Alibiet it does seem a little faster.

What effect does back pressure from the pipe have on the overall performance?


Thanks!

[Zino]

2 stroke pipes need some back pressure from the sound waves to both suck exhaust out of the cylinder and then jam extra mixture in to improve the performance
Think just like how a turbo works

[jonnyrocket]

Thanks Zino!

I'm pretty happy with how it turned out! Thanks to you and the time you put into your journey on this site! I am still tweaking it. It's kinda weak on the start then once it hit the powerband it takes off. Sometimes the speedometer goes off the scale, and sometimes seems like 37 is the fastest. My CVT is all stock though too. I tried some 7 or 8 grams I got cheap but that was really bad. Maybe CVT next?

[Zino]

put in your signature line what scoot you have and what parts over stock

you just may need a refresh in the cvt
stiffer clutch springs medium or light will have you starting closer to the beginning of the power band

what you want is when you hit the throttle wide open you jump off the line with power if you roll slow for 30 yards and then pick up speed try stiffer clutch springs .

When you add kits and pipes they tend to move the power bands to narrower and higher .
you usually need to stay the same or go lighter on variator weights so you shift at a higher rpm

heavier weights have you start out in a higher gear and so you struggle on take off and then catch up as you eventually spin up in power band