weenieroaster
ArboristSite Operative
Possibly the best builders are those with the most self discipline. Restraint is a much overlooked quality when it comes to making things, both applying to one's self, and the object at hand. 
Biggest perpetuated Myths about Modded Saws.
- Thread starter Mr.
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Danger Dan
ArboristSite Guru
Possibly the best builders are those with the most self discipline. Restraint is a much overlooked quality when it comes to making things, both applying to one's self, and the object at hand.
Possibly :smoking:
husq2100
Addicted to ArboristSite
as i have said many times, I AM A NOVICE!
i spectated at the first races that i have ever been to on sat at Crowsnest
you and Fred know alot more than me, so i guess you could decide for yourselves how much room to leave for expantion and such under full heat and rpm, but i bet you want to get that piston as close as you safely can when building a worksaw
your post is quite funny as this has been my point all along re Fred not proving his thoughts but rather getting people to disprove them, and i have said many times im new and modding my first saw, but im guessing you already know this ...... : )
some guys here are very sneeky..hahaha
just not me, im to loud for that
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drmiller100
ArboristSite Guru
most of us are no further along then you are.
i've modded a grand total of exactly one saw. i'm pretty happy with it, and working on starting the next project.
i've modded and been around a bunch of snowmobile mods. I am also blessed to have as one of my buddies a guy who has taught me a lot about 2 strokes and why stuff works.
sometimes i think folks state what they believe to be true, then someone comes along and questions it, and it turns personal.
I try to not let it turn personal, but rather to use the opportunity to question my "facts", and find gains.
i've modded a grand total of exactly one saw. i'm pretty happy with it, and working on starting the next project.
i've modded and been around a bunch of snowmobile mods. I am also blessed to have as one of my buddies a guy who has taught me a lot about 2 strokes and why stuff works.
sometimes i think folks state what they believe to be true, then someone comes along and questions it, and it turns personal.
I try to not let it turn personal, but rather to use the opportunity to question my "facts", and find gains.
husq2100
Addicted to ArboristSite
drmiller, good to hear.
well i have no modding or engine background, im a carpenter and just like things that move.
yep we all can take stuff personal, but i guess that can depend on how something has been said to.
i for one know that im terrible at explaining myself, and even worse when i have to write it out.....
im just here to have a go...
cheers, Serg
well i have no modding or engine background, im a carpenter and just like things that move.
yep we all can take stuff personal, but i guess that can depend on how something has been said to.
i for one know that im terrible at explaining myself, and even worse when i have to write it out.....
im just here to have a go...
cheers, Serg
Serg,
Now you've said something I would like to comment on. "Closer" isn't always better.
On a worksaw, there really isn't much we haven't discussed.
For a racesaw, there is alot more to be discussed, but as you pointed out--- this is a worksaws forum. HEHEHE Hint--make a new thread and we'll all jump in.
Fred
weenieroaster
ArboristSite Operative
I know one thing- a difference of .010" in the squish of my 281 with the stock combustion chamber sure made it a lot harder to start.
Personally, I have not had any starting issues come up as a result of raising compression. I have found that low speed carb adjustments become more sensitive, in terms of the best position for idling and spool-up.....maybe starting. I think I might want to look for carb issues as the culprit, more than compression. I have read where other people have said this, higher compression=bad start, so I could be wrong.
drmiller100
ArboristSite Guru
i had the opportunity to run a saw in hood river 2 weeks ago.
it was really easy to start.
retard the timing 10 degrees, drill a decomp hole between intake and combustion chamber, and the saws start right up!!!
it was really easy to start.
retard the timing 10 degrees, drill a decomp hole between intake and combustion chamber, and the saws start right up!!!
weenieroaster said:
My tired old arms and hands complain anymore when forced to pull over a high compression engine. 15-18 years ago it was not a problem. I still like the performance of a high-compression motor so I'll just live with it.
weenieroaster
ArboristSite Operative
Oh, your starting difficulty referred to pulling it over. Sorry, I thought the engine wouldn't start easily. That's how I get too, after frequently starting my 076 that has no de-comp.
Crofter
Addicted to ArboristSite
Compression could be getting the bad rap for issues that are the result of other changes in the process of getting the higher compression. Common methods of jacking compression often result in too long intake duration and resulting lower base compression. Blowback from carb etc that makes carb adjustment harder for idle and make it difficult to get both good idle and midrange mixture (spoolup)
weenieroaster
ArboristSite Operative
Throw in a small leak from the metering seat, that wasn't problematical before the higher compression work was done, now given the richer low speed setting, flooding resulting in poor starting might become more a factor.
Crofter
Addicted to ArboristSite
I am not sure I follow how the leaking metering needle condition would be affected. IF the base compression is affected it does change the fuel mixture curve. The same amount of compression change, (if it was made without affecting base compression) would affect carburetion much less.
There is often confusion between squish velocity and combustion chamber pressure. They are not the same thing, though in a fixed head cylinder they are usually tied together. When you start machining the fixed squish band and piston surfaces you could get high compression with low squish or vice verse.
There is often confusion between squish velocity and combustion chamber pressure. They are not the same thing, though in a fixed head cylinder they are usually tied together. When you start machining the fixed squish band and piston surfaces you could get high compression with low squish or vice verse.
weenieroaster
ArboristSite Operative
Referring to the leaking, it's just an assumption based upon a recent situation with a modded saw. I can't describe it with much definition, other than to say that the best idle setting was different from the best spool-up one, and the idle was uneven, chain wanted to very slowly jerk around with it. I did some pop-off adjustments, and the setting became more consistent, but along with it was a tendency to flood. I found that the needle seat was bad, and after replacing it, everything smoothed out, starting is better too. I just figured that being a modded saw was a factor, possibly more demand on the carb with regard to more finely tuned settings. Longer intake duration on the saw compared to stock.
Crofter
Addicted to ArboristSite
Ok, I can see how perhaps if you had to lower popoff spring pressure to get a richer mixture, that it would worsen any needle to seat leakage condition. Intake duration is a double edged sword.
opcorn:
weenieroaster
ArboristSite Operative
I think another myth;
Modded chainsaws (woods ported), are harder to start. I'd say it can be the opposite, if the carb is dialed in correctly.
Modded chainsaws (woods ported), are harder to start. I'd say it can be the opposite, if the carb is dialed in correctly.
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romeo
Addicted to ArboristSite
LOL, that was my best subject, next to beer drinking and puking
OMG we went to different shcools togeather!
