Wrist pin

[ziptiejones]

Looking at a 70cc kit for an 04 vino. 10mm wrist pin, correct? I can't imagine it'd be 12 but I wanted to double check

[Zino]

10 mm is correct

[ziptiejones]

Sept 26, 2023 18:05:50 GMT -5 Zino said:

10 mm is correct

Awesome. Thank you. What kind of jets do I need? I googled but there's different ones that come when I search and I want to make sure I get the right ones.Also do I need to worry about changing the oil jet? I was told that they usually come pretty rich from the factory out of caution but I wanted to double check.

I've also seen "squish" and "port timing" thrown around a little. I think I understand squish, it's more or less a compression ratio thing, correct? Kinda like milling a head down to bump up CR. But what is port timing?

[Zino]

I run stock oil pumps in my vinos
The yamaha pump works fine up to 10k rpm plus builds

here is a post from my thread
Ordered Jets that would fit the stock carb Mikuni style from 67,70,72,75,77
From these guys
www.jetsrus.com/a_jet_kit_scooter/yamaha_50_vino.htm
Yamaha has a Mikuni style carb called a Teikie and different size jets for tuning are hard to come by .
So I ordered a range that should get me close .
In the past Mikuni #'s for my Zuma had to be 5-10% higher than the stock main Teikei Jets to give similar results

my vino thread pushed 50 mph with a sport pipe and malossi sport cylinder
49ccscoot.proboards.com/thread/26756/yamaha-vinos-stealthy-build

this is a extremely fast vino build by guti same cylinder faster pipe gears and bigger carb
49ccscoot.proboards.com/thread/27281/70mph-yamaha-vino

[Zino]

you are correct
Tightening up squish bumps compression up take it too far and you have to run higher octane gas because of detonation

Port Timing
The ports in your cylinder exhaust and intake have a peak filling and evacuating of the cylinder
The timing part is the Rpm that this happens at
Another way people refer to it is the power band

Depending on your goals and budget
Reliable Daily rider that pushes 45-50 mph You dont even have to worry about these and gets done for around 500 bucks

When you are trying to push port timing to higher rpms levels and run higher compression
You will need a bigger carb a better pipe that matches to the port timing of the cylinder and a better transmision
This gets expensive quick and you will be well over 1000 bucks

[ziptiejones]

That is awesome stuff Zino I really appreciate it. We had already ordered an Athena bbk, and tecnigas silent pro exhaust but that should still be pretty close to your malossi set up I assume. I saw on another thread you and another member recommended a polini or malossi variator set up. Is there a considerable difference in the two?

What is chamfering the ports?
Why or what benefit was there to going up a tire size on rear?
What do you use/how do you raise the exhaust port? Just stack gaskets or cut a stencil from a different material?
If I did want to increase squish, what is a reliable way to do that at home? Or should I just have a machine shop take like .5mm off?

I hope I'm not asking too much. I really appreciate the information you've supplied so far and I'm super excited to get all this put together.

*Edit* quick Google search taught me about chamfering.

[Zino]

Chamfering is just knocking the sharp edges off the cylinder
The same files that use for chamfering is what i use to raise the ports on a cast iron block.

Since you bought the athena and it is aluminum cylinder with Nicasil
You will not need to chamfer the ports the nicasil liner on that cylinder is already chamfered .
Unless you by special grinding tools raising the exhaust port is not easy if you chip the nicasil you might have made a paperweight

The athena comes with different size base gaskets so you can raise or lower port timing with the base gaskets.

With the athena
I have often just used copper spray only to get down close to the .9 squish they recommend in the cylinder instruction.
Anything close to 1 is good enough

I have run an athena and silent pro set up
the silent pro pipe makes power down low and runs out of steam in the mid 9's
Raising port timing would be a waste of time
So to set the athena to match it run the thinnest base gasket that gets you close to .9 squish.

I have run both variators they both work well
With the silent pro and athena it has a very wide power band so yo can run weights that are close to stock or up to 1 gram lighter

[ziptiejones]

So smallest base gasket(in-between cylinder and case)
Copper spray between head and cylinder

That's the route I want to go?

[Zino]

So smallest base gasket(in-between cylinder and case)
Copper spray between head and cylinder

That's the route I want to go?

Yes That has worked for me to get the tightest squish .
Measure squish to make sure .
Any where close to 1 will make a big difference compared to above 1.5 mm

You might be able to run the head gasket to stay in those ranges .

[aeroxbud]

The cylinder head has a o ring gasket, so no need for copper spray.

[ziptiejones]

How would I measure that to make sure?

[ziptiejones]

I haven't had a 2T apart before so if it'll be obvious when I get in there you can just say that 😂

[Zino]

the athena instructions tells you how to measure squish

with the cylinder assembled with smallest base gasket and copper head gasket tightened down to proper torque .
You just take a piece of solder bend it .
stick it in the spark plug hole and turn the engine over and then measure how thick the solder has been pressed down to .
If it is close to 1mm your done
If it it is above 1.5 mm
Try mocking it up without the head gasket copper spray only.

Athena Big Bore Cylinder Kit (70cc Bolt On) - 47.66mm Bore model number 070200 does not have a o-ring head so you use the copper gasket it is the sport model

[ziptiejones]

Okay word. Kinda like a plastigauge. I think that it was called. For assembling engines and measuring bearing clearances. But basically I'm just looking to see how close the top of the piston at TDC is to the spark plug, correct?

Also, thank you so much for all the advice and support here.

[Zino]

top of the piston to cylinder head is what you are measuring

here is a couple helpful posts from the directory on the left
49ccscoot.proboards.com/thread/345
49ccscoot.proboards.com/thread/556