My DIY porting progress

So after 3 hours in the decarboniser at work and a was in a dishwasher () I started to poilish the top of the chamber and valves heads and de-burr the intake and exhaust ports
Top of chamber and valve heads

Intake port

Exhaust port (needs polishing)


Next is to polish the exhaust port and start on the other head

Aren't intake ports supposed to be rough to aid swirl and fuel/air mixing?

Originally Posted by Razor

Aren't intake ports supposed to be rough to aid swirl and fuel/air mixing?

Yeah, i'm going to leave them as they are, its a 40 grit finish. The exhaust ports will be alot smoother

Don't forget to match the exhaust port opening to the exhaust pipe. There is a horrible mismatch there with the port being 5-6mm smaller than the pipe size !!!!! I see you thinned out the exhaust web too.

Don't get hung up on making it shiny, just get the shape right. You can also remove the tiny ridge around each valve seat in the combustion chamber. These are made by the valve cutters and most likely aren't there on purpose.

Don't expect big gains, the exhaust port matching will help the most, too much metal removal or increases in cross section will hurt velocity.

I couldn't leave mine alone either. I reccommend the cam swap while your in there,.. it will make a difference.

[northwind]

He's already done the cam swap

Originally Posted by KAYAKER43

Don't forget to match the exhaust port opening to the exhaust pipe. There is a horrible mismatch there with the port being 5-6mm smaller than the pipe size !!!!! I see you thinned out the exhaust web too.

I thought the ports are miss matched on purpose to stop exhaust back swirl going back into the chamber EDIT: i found out this doesn't matter to much on a 4 stroke engine

Originally Posted by KAYAKER43

Don't get hung up on making it shiny, just get the shape right. You can also remove the tiny ridge around each valve seat in the combustion chamber. These are made by the valve cutters and most likely aren't there on purpose.

I'll polish the exhaust port as planned (to help stop carbon build up) and i'm planning on lapping in the valves when it time to reassemble. I think the ridges are the to give a bit more adjustment when grinding...if you know what i mean

Originally Posted by KAYAKER43

Don't expect big gains, the exhaust port matching will help the most, too much metal removal or increases in cross section will hurt velocity.

I've done to much to my SV over the years to know not to expect to much when i've finished a mod But i am interested in the exhaust port matching now

Originally Posted by KAYAKER43

I recommend the cam swap while your in there,.. it will make a difference.

I recommend it too

For comparison, i thought i'd post up pics of my other head after cleaning in a decarb. The mould lines and burrs are what i'm taking out plus the bump on the bottom of the intake and on the exhaust side i'm matching the port to the copper gasket thats in there