Does outside temperature effect performance of engine?

[Tree94]

I live in Arizona where it gets 100+ degrees.
Sometimes I have a tough time starting my saws and blower.

My helper says its, "vapor lock". he says the fuel is so hot its just, "vaporizing" in the engine.
Im not too sure how I feel about that.

Any thoughts on this?

Thanks.

 

[KYsawman]

Temperature does affect engines in that the mixture changes with temperatures and altitude.I grew up in Alaska riding and racing snowmobles, you would have to tune for temperatures and altitude. The manufacturers had recommended jet charts to follow. It is the same for outdoor power equipment.

 

[Deets066]

I noticed it more in my snowmobile, the colder it gets the more dense the air- more oxygen. 2 strokes run leaner the colder it gets.

 

[Terry Syd]

https://wahiduddin.net/calc/calc_hp_dp.htm

Its not 'vapour lock' - its because your engine is running much richer.

 

[GrassGuerilla]

Yep, that's why I really get miffed about tamper resistant carb adjustment screws. They're a license to rob a guy that runs 2-strokes year round.

 

[Tree94]

So in my case, a simple carb adjustment is all that is needed?

Thanks for the replies guys

 

[Ronaldo]

Could be. They definitely need some tuning when going from warm temps to cold, and some saws are a bit more touchy than others.
Example: my 371XP is very sensitive to temp changes and my Jons. 2152 is not.

 

[Festus]

My basic understanding is the percentage of oxygen stays the same. About 20.9%. However air density changes with temperature and/or altitude. I had an old Evenrude outboard that had little levers (or knobs) on the carb adjustments, with a flip down door for easy access. Not likely to every see that again.

 

[Rx7man]

They'd much rather have carbs that never run quite perfect than one a feller can tune easily... That's what I liked about the old Homelites with the extra long mixture screws that came out on the side of the case.. didn't need a special screwdriver to get to them... My ported saws are more finnicky about tune than my stock ones... any significant change in temperature or elevation requires a tweak of the mixture screws to either prevent them from bogging or chugging at the top end.

 

[ChoppyChoppy]

For the vast majority of OPE users, fiddling with the adjustments is a recipe for failure.
Have had probably a dozen saws come in this year "won't run", and was just from the carb being adjusted way out of wack by someone with no clue.

I have no idea about 100*, I don't normally cut wood right near the woodstove (haha), but if I have a saw running nice at 65*, it usually needs a little adjustment at -10*.

 

[Tree94]

For the vast majority of OPE users, fiddling with the adjustments is a recipe for failure.
Have had probably a dozen saws come in this year "won't run", and was just from the carb being adjusted way out of wack by someone with no clue.

I have no idea about 100*, I don't normally cut wood right near the woodstove (haha), but if I have a saw running nice at 65*, it usually needs a little adjustment at -10*.

So whats the secret to learning how to properly adjust the carb? Is it just practice or something I could research and teach myself?

 

[1Alpha1]

Outside temp. absolutely does effect the performance of OPE.

So much so, that if it's too damn hot or cold out, I don't cut.

 

[Ironworker]

So whats the secret to learning how to properly adjust the carb? Is it just practice or something I could research and teach myself?

There's plenty of info on here, the web and YouTube along with some expierience should be all one needs. Madsens is good.
http://www.madsens1.com/saw_carb_tune.htm

 

[Tree94]

There's plenty of info on here, the web and YouTube along with some expierience should be all one needs. Madsens is good.
http://www.madsens1.com/saw_carb_tune.htm

Thanks man

 

[blsnelling]

So whats the secret to learning how to properly adjust the carb? Is it just practice or something I could research and teach myself?

Check out the link in my sig.

 

[Tree94]

Check out the link in my sig.

Nice! I'll be watching those later this evening

 

[Ronaldo]

Check out the link in my sig.

Brads here is one that I found most helpful when I was new to this tuning business!! Thanks

 

[AKDoug]

OPE that sits in hot temps can have issues other than tune. A saw fueled when it's cool will build tremendous amounts of pressure when sitting in the heat. Just take a look at what happens to unvented gas jugs. The tank "vent" on a piece of modern OPE is not really a "vent", it is a one way check valve that allows air INTO the tank when vacuum is applied. If pressure is applied, through expansion of the liquid in the tank, it will not let that pressure to bleed off. The mega amount of pressure is released when you try and start the piece of OPE, often flooding it. I see it all the time when saws are brought into my shop in the winter. Saw topped off at -10F, and then brought into the 70F shop. I always remove the fuel cap to relieve pressure after the saw has warmed up.

If the saws are giving you problems even after pressure is neutralized, then it's a tune issue. You need to lean for warmer temps, but you HAVE to remember to richen them back up for cooler temps.

 

[Deets066]

At 100* would it be to his advantage to run a plug with a hotter heat range?

 

[AKDoug]

At 100* would it be to his advantage to run a plug with a hotter heat range?

No clue at 100* I melt and die.