RD 350 transfer port cleanup

[Dvsrd]

Gents,
I have a spare set of stock RD 350 cylinders, still at stock bore, that I am considering having bored to +.25 or +.50 mm, as well as converting them to RD400 head gaskets and fitting dowels to locate heads.
Is it worthwhile having a local 2 stroke shop clean up the transfer ports first. Just removing any steps and casting flaws in the upper part of the transfer ducts and the ports. And maybe cutting the boost ports a bit deeper as well. No plans for more exhaust port duration, however.

[1976RD400C]

If you have an air compressor you could buy a die grinder at Harbor Freight and clean up the ports yourself.

[m in sc]

if you local shop has a porting tool, then yeah its not  bad idea, the roofs of those ports shaped and cleaned up can def help.

[Dvsrd]

I do have straight die grinder, a Dremel etc, but no right angle handpiece. And since those are pretty expensive, I am looking at having this done by a somewhat local shop. I can easily deal with intake and exhaust ports myself, but do not intend to change timing, maybe just improve the exhaust port finish to slow down carbon buildup.

[automan]

Sand blast

[sav0r (CL MotoTech)]

Reducing and removing the ledge is basically the first thing you do. Matching the sleeve at the divider is common. I see a lot of knife edged cylinders there. Knife edging is easy but it's old school. Nice rounded and blended ports are preferred. Then clean up and set port timing.

[IR8D8R]

I picked up a Chinese Vevor Foredom knockoff flex-shaft grinder and a right angle attachment on Amazon for ~$150. That's really the setup you want for port grinding cylinders. Dremels don't have enough power. I've used air die grinders on cast iron ports and they're so noisy and really require a big compressor tank and 2 cylinder compressor head. My 20 Gallon 5hp Sears compressor won't keep up so I have 2 compressors feeding the same air line. Super noisy with all that running in my shop.

A real Foredom is almost $300 without the right angle handpiece which is almost as much as the tool. I'm pretty happy with the Vevor even though I'm not fond of sending my money to China. My only complaint is that the foot switch is not variable speed. Just on/off.

IR8D8R