Who warms up the engines?

[Gary1234]

Idle ???? ... What's that ???

I never let my saw idle ... idle speed is bad for any engine (my own motto) ... an engine is better stopped and cooling off than building up heat during idle. I also turn the saw off if I put it down for more than 10 seconds. From my own experience, idling tends to wear the engine needlessly.

 

[Lakeside53]

I never let my saw idle ... idle speed is bad for any engine (my own motto) ... an engine is better stopped and cooling off than building up heat during idle. I also turn the saw off if I put it down for more than 10 seconds. From my own experience, idling tends to wear the engine needlessly.

The flywheel fan from the idling engine cools the saw. It's important to idle the saw for a short time after hard use to remove the excess heat...

 

[Gravely Grinch]

I always warm them up before cutting and idle them after a cut to let the engine temp stabilize before shut down. 200 RPS is hard on a cold engine.

 

[Diesel JD]

I didn't use to woarm up except to get teh saw to respond well tot throttle as some otehrs have stated, but after I found AS I started idlling it for about 30 sec. to a minute before I cut anything. I figure it is qualitatively different from a liquid cooled engine which needs some gentle driving at least(especially my diesel) before it will begin to warm...with an air cooled there will be less to stop the combustion chamber from warming, plus a chainsaw is only a small 12 cylinder engine, which means less surface to heat up. Just my 2 bits.
J.D>

 

[Freakingstang]

I have a ZIMA carb on my 55 and have no problems with it. Ken

Nothing wrong with the Zama's, as most are a Walbro knock off. I have two 55's that both have been modded and the Zama is fine. It was just a design flaw on the 365's. Husky put too small of a carb on them to try to stop the HP potential of them.

 

[Lakeside53]

It was just a design flaw on the 365's. Husky put too small of a carb on them to try to stop the HP potential of them.

oh no.... not Husky too... Being on this site for the past year lead me to believe only the Evil Stihl did such things.. I'm shattered...

 

[04ultra]

We always warm um up for about 30 seconds ..They run great and haven't let us down yet..

 

[dingo]

I suppose it doesn't make much difference, but the saws have needle bearings and the vehicle engines have inserted bearings, As soon as the saw gets a good throttle response we throw the cobs to them.

 

[THALL10326]

I suppose it doesn't make much difference, but the saws have needle bearings and the vehicle engines have inserted bearings, As soon as the saw gets a good throttle response we throw the cobs to them.

Warming up brings up a interesting question based on what I got a chance to see. I had the liberty of walking through the Stihl factory down at Va Beach a few years back. In one section they were in the process of manufacturing some MS250's. Each saw goes into a test cell and is runned. The engine is brand spanking new and it runned wide open throttle 5 seconds after it goes in the test cell. Though these motors are at house temp. they aren't warmed up at all before hitting full throttle. I myself always let my saws warm up before giving them the dickens but at the factory they letem rip right off the assembly line.

 

[madmax]

That is because it isn't getting enough fuel at Low circuit. It must have a Zama carb. If you want to fix it, get a Walbro off of a 372. Been down that road a couple times. If yours is one of the lucky ones with a Wlabro, richen the low jet a little. Should solve it. If you keep the settings where it is at, it will continue to get worse are small particles make there way into the carb in the form of Dirt.

I put Walbros on both of mine. No off idle hesitation, Husky eventually switched to the Walbros, but mine were old enough to have the Zama's. I just don't know what year they did.



Steve

Cool trick, Have two p-42 pioneers that I always had to let warm before they would even start to cut, both have walbro carbs, richened the low jet like posted above, and they will both run like they were hot when u hit the first cut, thanx. (Still gonna let them warm up though)

 

[JohnL]

I warm them up, same with cars/trucks. The wear on metal is faster when it is cold.

 

[madmax]

Do the rings being cold vs expanded make any difference worth being mentioned?

 

[hydro2]

I always let mine warm up for a minute or so. Don't know if I am wasting my time or not, but often wondered.

 

[Gary1234]

Shut it off ...

My opinion (for what it's worth) is that idling the saw will somehow dissipate more heat than shutting it off ... is a myth. With a 4 cycle engine there is some truth to idling after a wide open throttle run ... some red hot valves would be left open and uncooled ... not so with most 2 cycles.

As for starting a 2 cycle, no need to let oil pressure build so why idle? Engine failure is most likely to occur from metal fatigue and high temperature ... the result of long periods of WOT operation. Under what theory would readers think that running a cold engine at WOT would cause early engine failure?

 

[sawn_penn]

I agree that there's little point idling-down an air cooled two stroke.

On the warming up side of things, metal expands when heated. While an engine is warming up there is a very uneven distribution of heat, so the moving parts are slightly different sizes and shapes than they would be when the engine is fully warm. Placing significant load on the engine when it is mainly cold causes more wear than if the load was applied to a fully warmed engine.

However....

A two stroke engine is a pretty dumb bit of technology. These engines are cheap. I doubt it's worth your time + fuel standing around waiting for a saw to warm up to save a bit of time between overhauls.

People get paid for getting the job done, not for making a saw last 20 years.




(that said, I don't earn my living cutting wood...)

 

[Sprig]

That isn't under load though, they just want to see if anything breaks!
I've always done as gypo does, give her a sec or two and have at it, after all, they are air cooled, what does it actually take to warm a saw up? At the most I figure about 1-2 minutes at idle, biggest prob would be really cold and the chain oil is too thick lol. My little Sthil is ready in about 2mins, wot is no prob from there, that is what they are made to do after all.

 

[DeanBrown3D]

My opinion (for what it's worth) is that idling the saw will somehow dissipate more heat than shutting it off ... is a myth.

But it does say to do this in the Stihl manuals.

 

[v8titan]

My opinion (for what it's worth) is that idling the saw will somehow dissipate more heat than shutting it off ... is a myth. With a 4 cycle engine there is some truth to idling after a wide open throttle run ... some red hot valves would be left open and uncooled ... not so with most 2 cycles.

I do think there is some merit to a short idle cool down after high load / full throttle running of any engine. Keep in mind that most modern 2 stroke engines are aluminum alloys with high Tc (coefficient of thermal expansion). Some areas of the motor will be extremely hot, like the area near the exhaust port and some cooler eg. near the intake. This drastic temp difference is maximum when the motor is running full throttle under load. If you shut down immediately after full load service I would think the risk of introducing stress or even warpage into the cylinder is a possibility. A brief cool down idle (30 seconds or so), allows the fan to cool the hottest surfaces near the exhaust outlet more uniformly. Just thinking about this from a materials standpoint.

I own an Echo back blower that warns that a 1 minute cool down before shutting the engine off is necessary.

That's my $0.02.

 

[WadePatton]

Just think of the value of all that warm up/down time. Time (those of us that do) we get to enjoy nature, pick our teeth/nose, allow the earplugs to fully expand, take a whizz...stuff that other folks just don't have time to do.

Life's too short.

 

[buck futter]

I leave the saw on fast idle for 10-15 seconds and then knock it down. If it is real cold and you knock it down to fast it seems like it just dies out. After the fast idle I'll let her idle a few more seconds and I'm ready to cut wood in a minute. As far as the cold motor no having lube two things contradict that, anytime I have opened up a two stroke there is always some oil residue in there, also as long as its getting fuel it is getting oil ( lube ). Listen to the saw and take it easy until shes hot wet and ready to rock. I also think it makes sense to let the saw cool down by idling if you have been doing some significant bucking. if you have just trimmed a few limbs then the saw probably doesn't have the same amount of heat in it.

Buck