big_daddy234
ArboristSite Operative
Say you have .030 squish with gasket and .020 without, will it run better without? Does it improve timings or is it only compression that gets improved?
benefit of deleting base gasket?
- Thread starter big_daddy234
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I will let someone more knowledgeable comment on the timing. But deleting the gasket will improve compression and the "effective" stroke. The actual stroke will not change, but the piston travel past the ports will be increased.
fearofpavement
Trying them all
Whether the timing benefits is depending on what it was with the base gasket installed. Deleting the gasket will always increase compression but not necessarily benefit other parameters.
Are there any Stihl models that shouldn't have the base gasket removed?
jughead500
Sasquatch
Without cutting the squish i have ran into the 026,028,036.all were .015-.018.had to get the .5mm gasket.
most of the 066's I have done could NOT be run baseless.
most 460's need some gasket height as well.
Always check your squish not matter what the saw though...you'd be surprised what you find out.
Well, I have done this simple mod to three huskies I own, all with favorable results. It raised compression 30 to 40+ psi.
Which is fine, except..
I have one saw that went from 165 psi (before) to 210+ psi. Although I love the increased torque it now makes, it also generates a lot of heat. Which means (besides a switch to colder plug - no biggie), I have to feed it 93 octane. Otherwise, on warms days and/or long runs it starts to detonate. It also means, for the sake of convenience I now use more expensive gas in all my equipment :~\
Which is fine, except..
I have one saw that went from 165 psi (before) to 210+ psi. Although I love the increased torque it now makes, it also generates a lot of heat. Which means (besides a switch to colder plug - no biggie), I have to feed it 93 octane. Otherwise, on warms days and/or long runs it starts to detonate. It also means, for the sake of convenience I now use more expensive gas in all my equipment :~\
Jug, do U make those 5 mm gaskets, or R they available?
HuskStihl
Chairin'em for the sound
sunfish
Fish Head
With 6 modified saws I've never experienced more heat with higher comp. Colder plug? No help there. Never had any detonation either? Run 91 now, but no problem with 87 either?
nmurph
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...and I've done hundreds of base gasket deletions and never gained more than 15psi, and the typical gain is 7-10psi. Gains of 30-40psi require machine work.
well then maybe you need to "mod" yer compression gauge !!!!
everybody else gets hunnerds a PSI's extra
You guys may be using different oil ratios, that will effect octane. More oil is like running higher octane, it does not ignite as easily as gas.
I don't know who is correct in this debate, but I always run high test fuel because I hear that the saw runs cooler with it, and that should help it last longer.
It likely will not make any difference except in extreme circumstances, like a very hot saw on a very hot day, or milling, etc.
I don't know who is correct in this debate, but I always run high test fuel because I hear that the saw runs cooler with it, and that should help it last longer.
It likely will not make any difference except in extreme circumstances, like a very hot saw on a very hot day, or milling, etc.
I tested running 110 with saws in the 170 lbs of static compression and they slowed down 10% for double the cost of the gas. I haven't done timed tests with 87 and 93 yet but treemonkey says 87 makes the most power even with saws running 230 lbs of compression.
sunfish
Fish Head
I found the same thing with my saws (170-200 psi) and 100+ octane.
HuskStihl
Chairin'em for the sound
I have done literally three base gasket delete's. 385 went from 150 to 175, 350 went from 145 to 170, and my supermike 288 blows 200 with a gasket, and ballpark (right arm limited) 230 without. Granted the last one has a cut band.
sunfish
Fish Head
I have two 357s' blowing 190 & 195 with just a base gasket delete.
Jon, your saw must be defective. Give it to me ;~]
Discovering the issue was hard for me since the way most of us can tell is we hear engine metal ringing at 6.5khz; kinda tough when the saw is screaming. My hearing ain't so great anyway. There are many variables at play here: Maybe my saw's ignition timing is too aggressive. Plus, you can have detonation going-on and never know, never have problems. Especially part throttle. That is not a flame. I don't want to start a flame war. As for the cooler plug, no, it is not a fix for detonation, per se', rather it is a hedge against detonation*induced* pre-ignition.
jughead500
Sasquatch
From the stihl dealer.they have 2 part numbers 1 for .5mm and 1 for 1mm
