Mastermind Meets The Echo CST-610EVL

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
I got all four of the av bushings squared away and checked port timing and squish. Both jugs are spot on.....

EX: 109
TR 121
SQ .021
 
I got all four of the av bushings squared away and checked port timing and squish. Both jugs are spot on.....

EX: 109
TR 121
SQ .021

Well, that is a lot of transfer duration on a 30`ish cc cylinder! :msp_ohmy: As I remember from the times I used to port a lot of string trimmers, 127* to 130* depending on port withs, would be more like it on a 30 cc cylinder. :msp_thumbup:
 
Those are some crazy numbers. Only 12° of blowdown!

I agree.

It has a domed piston crown as well. I've figured out how to cut the squish in those though. I intend to take enough out to allow me to raise the exhaust, still have good solid compression, and gain some blowdown.

I'm not planning on going over 170 on compression on this one though. A crankshaft weakness has been mentioned before and there are no decompression valves.
 
I agree.

It has a domed piston crown as well. I've figured out how to cut the squish in those though. I intend to take enough out to allow me to raise the exhaust, still have good solid compression, and gain some blowdown.

I'm not planning on going over 170 on compression on this one though. A crankshaft weakness has been mentioned before and there are no decompression valves.

Those small cylinders are very easy to overport because of small volume to wall area relationship.
 
Wow that's one heck of a project. I am quite interested to see how you do. I have one of those 610 POS's and I can't stand using it, for its lack of power. If this one turns out good you will be seeing another in the near future.

To respond to an earlier post, the pistons move in exactly the opposite direction of each other, thus cancelling each others motions out. The crank needs no counter balancing. Because they fire at the same time, they can be run with one carburetor and one coil. A very smooth running saw.
 
Wow that's one heck of a project. I am quite interested to see how you do. I have one of those 610 POS's and I can't stand using it, for its lack of power. If this one turns out good you will be seeing another in the near future.

To respond to an earlier post, the pistons move in exactly the opposite direction of each other, thus cancelling each others motions out. The crank needs no counter balancing. Because they fire at the same time, they can be run with one carburetor and one coil. A very smooth running saw.

I'm thinking it should be much better......I do wish I could have used it enough to get a "feel" for what was lacking.....
 

Latest posts

Back
Top