Here's a pic of a good 066 port (worksaw)

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Mr.

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Tell me what you think.

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Fred
 
Fred, that's so pretty it brings a tear to my eye. Nice!!

What Senior' Rotten asked, what are you using to grind it, and what to polish it.

Mark
 
Fred, what did you use to get that port that smooth???


I have had good luck with the abrasive impregnated rubber buffers...........but never got that shine!!!

I only used a double cut bit, sanding disk, a little square I cut off a scotchbrite pad, and felt/rouge. I used the same arbor for the felt and the scotchbrite.

Main thing is to have a steady and slow hand. If you make a mark it will be real tough to get it out.

Fred
 
The finish looks good and I commend you on that because I know how hard it is to get that much of a quality look. Now for the real question did your rais or lower the port? Doesn't look like you widened it by much there is still alot of material you could have removed to make a rounder port that would flow a little better. I wouldn't raise the exhaust at all because I think the bbs are lacking in the torque department from the get go. lowereing won't gain you anything either. It does look nice though.
 
Tell me what you think.

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Fred
Too "rectangular", the finish is nice but inconsequential. Don't touch the intake, just deburr the casting ridge. Don't touch the transfer ports!!!.The exhaust port should measure 56.50mm from the base when you are done on this saw. To gain more effective intake duration, take 0.080" from the intake side of the piston skirt. Machine 0.010" off the piston crown but only cross-feed 0.375" on your lathe, next throw away your base gasket, you will now have 0.020" clearance between the top of the combustion chamber and the piston at TDC. Seal with Permatex Ultra-Grey. Remove the muffler, cut the basket open with a die-grinder using a 1/32" X 3" Walter slitting wheel, don't leave any burrs that may come loose. Install the hi-flow exhaust casing but cut an extra hole 7/8" in diameter and install an exhaust outlet from a 288 Husq. PN 503 0783-01. Remove limiter cap on hi-speed needle, adjust to 1-1/8, leave the low-speed alone. Now you are in the ball-park. Simon.
 
Seal with Permatex Ultra-Grey. Remove the muffler said:
Why permatex Ultra-Grey and not DIRKO? When removing the baffles out of the muffler I have found the easiest way is cut with a small air body saw the points where the baffles attach to the top of the muffler body. Then take a center punch and punch a mark in each spot weld that is in the baffles (you will probably have to get a light and look for them sometimes there hard to see) there will be either two or four most likely four. This is all assuming you have a new enough muffler with the baffles if not then don't pay any attention to me.:givebeer:
 
I have tried several products. Loctite used to make a 2-part system that worked well. Ultra-grey has given me the best results in the last two years and last 344 modded saws. Cheers.
 
Don't touch the transfer ports!!!. Simon.

I agree Simon. Beginners should not touch the transfers.

As far as being too rectangular............... if you know how to bevel for a squareish roof then there are no problems. If you don't........... you'll stuff a ring land every time.

Everything must work in concert.

Fred
 
A couple of questions concerning what has been stated in the thread.

1) Having a nice "finish" on the exhaust port will not help flow to much but does reduce carbon build up. Is not this important too in a working saw?

2) How does shaving the piston effect engine balance? Should the counter weight on the crank be trimed a bit too? For that matter does anyone bother to balance modded saws?

2a) Concerning question 2 above how close in weight are aftermarket/big bore pistions to NOS pistons? Has anyone looked at this?

P.S. Have not done much saw porting but quite a bit of work on moto-cross bikes. I think many of the same principles apply but you are looking for a different power curve................

P.P.S. Thanks for your insights!!!
 
First, quantify #1. Just because tuners that don't want to do extra work have said it and people accept it does NOT make it true.

I polished it because it didn't take much extra effort because of a steady hand with a porting tool. You don't have to do it, but WTF.

The aftermarket kits are all over the board. Balancing is quite linear with a single stroke engine.................

Fred
 
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