MS462 timing numbers

[Tim Gordon]

I’m sure someone has seen and/or done this lol
but I’m porting my ms462, it being the first mtronic/auto tune type saw I’ve ported and timed
I’ve zeroed them degree wheel
With no base gasket and squish of .020 I’m getting
98° on the exhaust
120° on the transfers
But it’s the intake that surprised me
84° On the intake (I know 160° Duration Is the preferred)
The piston skirt on the intake side is notched out already from factory so I’m wondering being that it’s an mtronic the carb, it is calibrated to limit the fuel to a certain extent no matter the intake duration
It’s a new piston from the dealer, and it’s the correct one
I hope someone can reassure me
On this
Thanx for now

 

[mattr66]

Remember that you have 2 sources of air to the system. One to the crankcase and one directly to the transfers.

Sent from my motorola edge plus using Tapatalk

 

[Tim Gordon]

Yea you’re right I forgot about that system totally
I’m just trying to visualize the inner workings of that style air/fuel delivery and it’s making a bit for sense now
Complete oversight on that “strato” system

 

[huskihl]

Without lathe work there’s not much to do. You could flatten the upper transfers. I wouldn’t raise the exhaust though.

 

[drf255]

Remember that you have 2 sources of air to the system. One to the crankcase and one directly to the transfers.

Sent from my motorola edge plus using Tapatalk

Bingo

Dont touch that intake port, even if you lathe it. There is a balance there that the factory figured out. If you open the intake more the saw will suck less air through the stratos and vica versa.

The tiny transfer opening is another head scratcher, but again, it’s carrying half the charge.

They improve with porting, but not as much as other models. The factory did its homework with them.

 

[Tim Gordon]

Wow guys thank you!!
exactly the answers I was looking for
I know when it comes to timing numbers, when someone else is doing it you have to take it with a grain of salt and assume that it is zeroed properly
Like drf255 said that the factory has kinda figured it out with the porting of the saws now a days, not saying you can’t do better just a little more calculations may be necessary

 

[drf255]

They have more time and money than anyone else to make their products marketable. Their products must be fuel efficient, emissions friendly, quiet and durable/reliable amongst other attributes.

We cannot beat their R&D. Anyone who thinks they can figure out a better way than the OEM can in their garage with some tools is a fool.

We simply aren’t bound by the same restrictions that they are and trade one of the above attributes for more performance.

 

[064AV]

I raised the exhaust a little on my 462 and it brought the rpms in the cut up, and I'm thrilled with the result in 24-34 inch tamarack! It out cuts a mildly ported MS460 and stock MS461 by an appreciable margin, so tomorrow I'm attacking my 046 to see if I can get it to beat the 462. I can't give numbers for the 462 because I didn't have a degree wheel when I worked on it, but I have one now so I'll know how I'm changing the numbers.