Suggestions on porting ms 500i

[Hoolio]

Hi everyone.
Just asking for your thoughts.
I’m pretty keen to do some porting to my newish 500i

I’ve done some porting to a few saws in the past, I basically understand timing no’s but don’t have experience in modifying them and what they do, so a change in timing will just be a guess.

I will check squish but don’t think I can delete the base gasket on these saws. So it will be stock compression, stock timing.

My plan is to clean up any dags etc in the ports,

widen the exaust a little, ( I think the ring end limits this anyway) and polish it.
Most of the 500i builds I’ve seen have benefited from raising the exaust, but they’ve had the squish cut so I was thinking I should probably leave the port height alone.

Smooth out the lower transfers.

I’ve already done a mm.

What’s your opinions, Is it worth doing these things, am I likely to even notice a difference?

 

[Sierra_rider]

Unless you have access to a lathe, I'd just leave it. You can't do a base gasket delete on them. There isn't a whole lot you can do to the lower transfers. You can do some shaping on the upper transfers, but if you don't have a right angle handpiece and the knowledge of how to aim transfers, I'd leave them. I don't have nearly the experience of some of the porters on here, but I generally don't like raising the exhaust port unless I cut the squish band and deck the cylinder.

I'm currently experimenting on my personal 500i, using 660 pistons. However, it's really not a DIY project, as it requires use of both my lathe and my vertical milling slide.

 

[Hoolio]

Sounds like an interesting project!


Why do you cut the squish band AND deck the cylinder. Instead of just decking the cylinder to get your 020 squish?
Is it to lower your intake timing?
Could you not do that by grinding the port?

 

[Sierra_rider]

Sounds like an interesting project!


Why do you cut the squish band AND deck the cylinder. Instead of just decking the cylinder to get your 020 squish?
Is it to lower your intake timing?
Could you not do that by grinding the port?

I do that in order to shrink the volume of the combustion chamber and increase compression. The difference between what I'm shooting for and what the factory spec is on squish would be negligible. Plus, with a wider squish band(speaking of diameter,) it should also better fight detonation under load...I'm not going high enough on compression for me to really worry about detonation though.

 

[Hoolio]

Ok that makes a lot of sense. I’ve read ( haven’t checked mine yet) that 500i factory squish is 027, didn’t really think there would be much to be gained compression wise.
But I can understand better now, the change in timing would have to be factor too doing that.

 

[tripler]

Open up the lower transfers and cut the gasket to natch
Use the gasket to mark the case
Line the case with plastic and pack it with non hardening modeling clay then grind the case to match what you did to the cylinder lowers
Widen the intake don’t touch the floor just widen and square it up
Widen and raise the exhaust to 100*

 

[Hoolio]

Open up the lower transfers and cut the gasket to natch
Use the gasket to mark the case
Line the case with plastic and pack it with non hardening modeling clay then grind the case to match what you did to the cylinder lowers
Widen the intake don’t touch the floor just widen and square it up
Widen and raise the exhaust to 100*

Thanks is for this.
This is exactly what I’m after.

 

[Hman1024]

Thanks is for this.
This is exactly what I’m after.

Did you end up porting the 500i? If so, how did it turn out?

 

[Hoolio]

Did you end up porting the 500i? If so, how did it turn out?

I haven’t no.
I have bought it up on Facebook sites aswell. I’m still scouring for information.
Where I live, Australia if you ask most people about ported saws they ask “what is that?”
When you explain it they say “why don’t you just buy a bigger saw. “ no passion.
So it’s hard to get good info.
I now have access to a lathe too so my options are opened up, but need to learn how to use that.
I’ve read some porting 500i threads “snellerized 500i” etc where they give the port timing numbers. I’m not sure if I could just copy these like a recipe and make a good safe improvement in performance.