Starting and RPMs

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NovaMan

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When I start a car (which I realize is waaaay different than a chainsaw), I don't rev it to its redline right away; I let it warm up first. With my BR420, I can control the choke and throttle independently, so I'm able to start that without it revving very high. But with my 026 and its Master Control Lever, it pretty much revs to max rpm for a couple seconds when I start it if it's warm out. Is this bad?
 
It ain't gonna hurt it. It's a 2 stroke mang! No oil pump to worry about gettin' oil to the bearings... it's already in there.

Gary

Also, with a 4 stroke your oil will be be thicker when cold which means it moves slower. With the oil mixed on the 2 stroke that isn't an issue, just start-r-up and hold on tight.:chainsawguy:
 
if its getting gas, it's getting oil, so it is well lubricated. It might not be ideal to run it wide open like that until it's warmed up so everything can expand and such, but it's not going to have oil starvation issues.
 
Warm It Up

Upon first starting, I run mine at idle for three minutes then start cuttin'.

Check this out: http://www.charlesriverrc.org/articles/flying/michaelkuper_2strokewarmup.htm

and this: http://www.smellofdeath.com/lloydy/piston_diag_guide.htm

FOUR-CORNER SEIZURE
piston21.jpg


This piston has vertical seizure marks at four equally spaced points around the circumference. A four-corner seizure is caused when the piston expands faster than the cylinder and the clearance between the piston and cylinder is reduced. Another common problem of this type is a single point seizure on the center of the exhaust side of the piston. However this occurs only on cylinders with bridged exhaust ports. The main causes for this problem are too quick warm-up, too lean carb jetting (main jet), or too hot of a spark plug range.
 
it wont rev that high on start up if you hit the throttle... BUT 2-stroke should ALWAYS be warmed up before reving it high...
 
My 036 will do this if I am not onto the choke lever thing immediately. I've gotten to where I can hit it almost perfectly to stop it...that's touchy since the hand that needs to flip the lever is the hand pulling the cord to start. It may or may not be much factor in engine-part wear, but it is built in to my psyche to prevent such stuff as much as possible. Far as I am concerned, no cold engine needs to be run flat out at start if it can be avoided.
 
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My snowmobile "cold seized" a couple of years ago. One piston caught the top lip of the exhaust port, and it wasn't the bridges kind. It was started, pulled off the trailer and left to sit idling for about 10-20 seconds before I shut it off. We had made it half way around the lake (going only about 40mph) when it popped. This cc engine was notorious for that, so finding a new piston/jug wasn't easy. It should have been mostly warmed up by then. Bottom line is, some engines are more susceptible to it that others, adequate warming is important, and letting it hit max rpm without a load on it are bad. The saws wouldn't put it at 1/2-3/4 throttle when you choke it if the manufacturer thought it would detonate the engine.
 
My 036 will do this if I am not onto the choke lever thing immediately. I've gotten to where I can hit it almost perfectly to stop it...that's touchy since the hand that needs to flip the lever is the hand pulling the cord to start.
That's exactly it. I get to the lever as fast as possible, but I guess I just need to jerk it up rather than flipping it up to the next notch and then squeezing the trigger to get it to pop into the regular running position. Maybe I'll try that tonight.
 
Warm it up. I don't use the high idle on my saws. when they pop on choke, I squeeze the trigger to kick it off high idle, and then start it. I then let it idle for several seconds before use.

Metal expands with heat. The piston gets hot quicker than the cylinder does, so the piston "grows" a few thousandths inside the cylinder. There should enough clearance to allow for this, but if there is not the friction between the piston skirt and cylinder will cause damage. "cold sieze". Once the cylinder warms up, the clearances return to normal. Snowmobiles are known for it, saws are not as bad, but it is still a 2 stroke engine.
 
If you are starting it by the book it won't run that high of an RPM. The manual suggests that you place the chain brake on before setting the choke. When it pops you move the lever up one notch to "fast idle" and with the chain brake ON it won't sound like the cold engine is going to the moon.

Funny thing them manuals, they can ususally tell you most of what you need to know about a saw.
 
The manual says "...the engine must be returned to idling speed immediately to avoid damage to the engine and chain drive (clutch, chain brake)."
The advantage of having the brake on is I get to smoke my clutch instead of the engine, which I guess is the better option. But I'd really rather not damage the saw at all. I guess I just don't like the master control lever: I'm intelligent and experienced enough to operate a throttle and a choke.
 
The manual says "...the engine must be returned to idling speed immediately to avoid damage to the engine and chain drive (clutch, chain brake)."
The advantage of having the brake on is I get to smoke my clutch instead of the engine, which I guess is the better option. But I'd really rather not damage the saw at all. I guess I just don't like the master control lever: I'm intelligent and experienced enough to operate a throttle and a choke.

I don't care the procedure much myself, but it does seem to be a compromise. You would be surprised at the number of people that have never heard of engageing a chain brake when starting a saw.

I've tried about every way of starting a Stihl and this seems to be the best, to me. I would rather replace a clutch and or drum after a thousand starts than a piston.
 
I am aware that the manuals say engage the brake before starting, but I never do it. If you know what you are doing with a saw, why induce unnecessary wear on a part? Don't forget that high idle isn't WOT. How long does it really take you to fire up a saw, blip the trigger and return it to idle... 3 seconds is SLOW if you really think about it.
 
I prefer the single level myself, never liked separate switches/levers/rods. My saws don't hit WOT on the high idle position, probably somewhere between 1/2 & 3/4 throttle. I personally defer to the experts who R&D'd and produced my saws that they might have known a little bit about what they're doing. Plus, I've got thirty year old saws with this setup and original P/Cs still in serviceable condition. I can live that kind of service life. But if you don't like, or prefer not to use, just do like Troutfisher; push to full choke till you get the pop then put lever to normal operation position. Nothing wrong with options. I do not start with the brake on, that's safety (CYA) thing. Not for protecting the saw, but protecting operator from injury and thus the manufacturer from liability. I have never replaced a clutch on one of my original saws, on fixer-uppers and company saws but not my own. I do start mine using the high idle position and think nothing of it, but only leave it there long enough to even out(few seconds) then kick it down. I don't do extensive warm ups either, 20-30 seconds then let 'er rip. Saw engines don't require extensive warm up like four strokers or diesels. My .03 cents. I may be way wrong but have yet to fry a properly maintained saw in over 25 years of operating.:monkey:
 
OK, I worked at a place that did a monday check on all their saws. It was not uncommon for guys to start the saws and then hold them WOT for over a minute. In 20 years, I never saw a cold seizure, and some of the saws were there when I started.

Now, I don't recommend treating saws like that, but can't see where a very few seconds of high idle would be harmful to a saw. Remember the stepped high idles on carburetors that could not be kicked down till the engine reached a certain temp? That was on a 4 stroker.

If you think that the master control lever is a slap at your intelligence, I can't help you with that.
 
I tried it with full choke and then run and it worked pretty well, so I guess I'll just use that method. Even if it's completely harmless to the saw, I just can't stand to wing it up so much immediately upon starting it.

Thanks for all the advice and info, as usual. :)
 

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