What would be your choice to pep up a 357xp? One or the other. A 47mm big bore kit or a higher comp piston.
Joe
Joe
Up the compression or big bore
- Thread starter Joseph W Santora
- Start date
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Ryan'smilling
Addicted to ArboristSite
higher comp might require higher octane fuel depending on how high the comp would be.
If you want to have a go at porting it yourself get the 47mm kit and port it.
This way if it doesn't run better than stock you can put the 357 cylinder back on it or send it out to be ported.
This way if it doesn't run better than stock you can put the 357 cylinder back on it or send it out to be ported.
cuinrearview
Red saw lover
As stated, if a muffler mod, base gasket delete, and timing advance don't have you where you want to be with it it's time to send it out to a professional for porting.
Hey, Joe, this question, from another Joe. No opinion on your plans. I understand tweaking an engine to run better and more efficient. I have an MS 290 truck saw. It stays on the back of my truck 24-7. If it ever dies I plan on putting a 390 jug on it because I hear it really works well. It just won’t die. I’ve always lived by, if I need a bigger saw, I just buy one. If I need a longer bar, I buy a new saw with a longer bar. Hence I have 3 super 1050’s with 3 different bars. But, I was in the tree business, and it seemed every time a guy had to change bars, he tied the crew up for a half hour. So I made more money just having what was needed ready. Again, no judging or criticism, just curious. Do you like to make factory stock stuff work better, no room in the budget for an expensive saw? Why do you want to take this one apart? If you are like me, it might never get put back together. You should see my work bench.
If you port and or bore and do a muffler mod, seems a bigger carb would be in order so more air can flow through. Seems if you open up the back end, you would need to also open up the front end as well.
cuinrearview
Red saw lover
The 199 is fine for all but a race port.
I know nothing about hopping up chainsaws. But it seems a 2 stroke would benefit with and expansion chamber on the muffler. Dirt bikes use them and I have seen some race saws with them as well. I guess it may get in the way on a normal saw. Maybe an expansion chamber would require a reed valve set up on the intake side. Like I said I know nothing about hopping up a chainsaw. I'm sure my questions clearly show that.
cus_deluxe
Commie Satan turd
ive seen saws with pretty crazy compression that run just fine on pump gas. this to me is an overblown concern on the relatively small chainsaw combustion chambers.
seen 50cc saws blowing 240 psi run just fine on 87-89 octane.
D
Deleted member 117362
Guest
How tight was that squish?
In the motocross world 50cc bikes with high compression run race fuel up to 110 octane. Just thought it may cross over to the 50cc chainsaw world. I have ran VP U4.4 (105 octane) in my saws and have noticed an increase in power and torque over 93 pump gas, in a stock saw. Quicker revs and it doesn't bog as much under a load ether.
cus_deluxe
Commie Satan turd
.020 ish. big long cuts would starve it a little bit. my only point is that the octane thing gets talked about a lot, and ive yet to see a saw that truly benefits from high octane fuel.
edit: i think people get carried away thinking that lots of compression means a corresponding direct increase in power. i think thats true to a certain point, but pumping losses are a real thing, and a worksaw doesnt need massive compression in order to make power.
cus_deluxe
Commie Satan turd
unless its running on methanol of course
cus_deluxe
Commie Satan turd
ive seen time after time, vids of people disproving the idea that “race gas makes a stock engine faster”. seat of the pants feel is not a replacement for a stopwatch.
Then why is it when I run 105 in my stock saw can I bear down way more on a full cut in big wood and it not bog down to a stop as easy as it does on pump fuel?
cus_deluxe
Commie Satan turd
must be magic, cuz that sure doesnt jive with the science. now maybe on a saw that comes from the factory with higher than “normal” compression (typical with some dolmars it seems) then you MAY see a slight increase in “power”. but id bet the farm that you wouldnt notice anything significant running hi octane fuel.
cus_deluxe
Commie Satan turd
cus_deluxe
Commie Satan turd
theres a guy around me that races a 3 cube solo, no machine work, running on methanol. now that saw probly had the ex raised a bit from stock, which means less than stock compression. so how can a “low compression” engine run 110 octane methanol? because static and dynamic compression are two different things. at 18k rpms, that little thing is making plenty of cylinder pressure to detonate gasoline. point being, theres a lot more that goes i to it than just pouring race gas in ur saw and it goes vroom vroom.
cuinrearview
Red saw lover
I saw a saw on alcohol AND a pipe once. Dunno what the compression was tho.
