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I am certainly no expert on porting 2 cycle motors but have done a fair amount of engine modifications on other stuff. In other words I do have a reasonably good background and understanding of how flow characteristics affect engine performance.
So, this concerns a Jonsered 630 SuperII and this is what I have done. Picked up a meteor piston which is a windowed piston. I worked the piston over inside cleaning up casting flaws and eliminating or radiusing any sharp edges, opened the windows a little, all the while studying the stock piston and trying to get as much if not more flow out of the new one.
Then I moved on to the exhaust port and widened it by perhaps 3/32 on each side maintaining the stock roof height and nice radiused corners and straight sides. Worked it smooth and opened the port the whole way to the muffler as much as seemed right. Also eased the transfers and smoothed them as well but did nothing to the ports in the combustion chamber themselves. I also matched the intakes and did alittle opening and smoothing but not very much. Then opened up the muffler a bit and changed the exit from the stock toothed style to more like the Husky style. Set the squish to 0.022" with no gasket.
Sorry no pics as I know fully well that a pic IS worth a 1000 words in this situation. But posting pics is another thing I have to take some time and practice.
Now my question. I tune my stock saws by ear. Peak them out and then richen until I get a good steady 4 stroke and richen just a whisker more to be sure. Well I used the same formular to tune this motor and PB showed up at my shop with his tach. Stock 630 is supposed to be set to 13,000 WOT no load. We tuned his stock 630 to around 12,500 I think he said. I put the tach on mine that I have already tuned as per above. When I spooled her up she went to a little over 14,200 and sounded good. I richened her up to bring the rpm to 13,000 it smoked and sounded poor. So I started leaning out until it sounded better and didn't smoke but I was still up around 13,600 or better. Is this OK? Normal for a modded saw? I don't want to ruin the saw but it just wants to spin up more than the specs say it should.
It does a good job in the cut, 4 strokes a bit and pulls steady and hard.
Also noticed it went through fuel faster than PBs stock 630.
So I know there are a pretty good number of you that do a lot of porting and modding saws what do you think is my saw OK or did I over do something? This is the first saw that I have taken this much time and thought to improve and I have read threads on here until I'm cross eyed on more than one occasion. So I haven't done this blindly just not sure of my results. Thanks.
So, this concerns a Jonsered 630 SuperII and this is what I have done. Picked up a meteor piston which is a windowed piston. I worked the piston over inside cleaning up casting flaws and eliminating or radiusing any sharp edges, opened the windows a little, all the while studying the stock piston and trying to get as much if not more flow out of the new one.
Then I moved on to the exhaust port and widened it by perhaps 3/32 on each side maintaining the stock roof height and nice radiused corners and straight sides. Worked it smooth and opened the port the whole way to the muffler as much as seemed right. Also eased the transfers and smoothed them as well but did nothing to the ports in the combustion chamber themselves. I also matched the intakes and did alittle opening and smoothing but not very much. Then opened up the muffler a bit and changed the exit from the stock toothed style to more like the Husky style. Set the squish to 0.022" with no gasket.
Sorry no pics as I know fully well that a pic IS worth a 1000 words in this situation. But posting pics is another thing I have to take some time and practice.
Now my question. I tune my stock saws by ear. Peak them out and then richen until I get a good steady 4 stroke and richen just a whisker more to be sure. Well I used the same formular to tune this motor and PB showed up at my shop with his tach. Stock 630 is supposed to be set to 13,000 WOT no load. We tuned his stock 630 to around 12,500 I think he said. I put the tach on mine that I have already tuned as per above. When I spooled her up she went to a little over 14,200 and sounded good. I richened her up to bring the rpm to 13,000 it smoked and sounded poor. So I started leaning out until it sounded better and didn't smoke but I was still up around 13,600 or better. Is this OK? Normal for a modded saw? I don't want to ruin the saw but it just wants to spin up more than the specs say it should.
It does a good job in the cut, 4 strokes a bit and pulls steady and hard.
Also noticed it went through fuel faster than PBs stock 630.
So I know there are a pretty good number of you that do a lot of porting and modding saws what do you think is my saw OK or did I over do something? This is the first saw that I have taken this much time and thought to improve and I have read threads on here until I'm cross eyed on more than one occasion. So I haven't done this blindly just not sure of my results. Thanks.
