Cold wheather harm on my engine

[250X_project]

What kind of effect does colder weather put on an engine. I know they will not run to peak performance when still cold, but does it harm it any? Is the oil flow restricted? I know start-up itself is harmful, but is it worse in cold temps? This is just a question I have always had. Thank you

[†2005 400ex†]

as an engine warms up the aluminum or watever the engine is made out of expands, revving up an engine when it is cold is BAD because it causes the metal to expand too fast and can lead to it actually cracking, as long as you do not ride the bike hard untill the engine is up to peak operating temp, you will be fine and it is no harder on the engine than it would be in normal temperatures

[†2005 400ex†]

The other reason you need to let the engine warm up is because by the time the engine is warmed up, oil has had time to get to the head, if you rev the engine before this its very harmful, as an engine sits the oil drains down and sits at the lowest point it can find due to basic laws of gravity, it takes time for the engine to circulate oil back to the highest point in the engine which happens to be the head

[250X_project]

That's true, but is the oil thickened enough to resrict flow in the bore? Yet the head should be oiled under a minute or the cam would be gone.

[cmpearce]

on my old 250x and 250x/350x quad and now my predator.i ran 5w30 oil in the winter.(30 to below 0 degrees)and it was recomended by a really good honda mecanic.just let it warm up for about 5 minutes then take it easy untill the engine starts to warm up.

[†2005 400ex†]

yes, in colder temperatures try running a "thinner" oil

[250X_project]

bump for Wilkin

[wilkin250r]

Some answer are discussing problems when the engine itself is cold, like when you first start it. Sure, there are dangers there, but I don't think that's what the original question was about.

Is it harder on your engine to ride in winter when the outside air is cold? There are a few issues, but most of them aren't actually severe enough to become "dangers".

Some will say that your jetting gets leaner, because cold air is more dense. Yes, this is technically true, but it's not a real big problem, I've never seen anybody actually have a lean seizure because of cold weather messing up their mixture. I wouldn't even worry about it.

Cold temperatures require more warm-up time. Not simply because the engine is colder, but because the OIL is colder, and it takes longer to heat it up and thin it out. Engine oil simply doesn't circulate well until it warms up. This only affects you when you first start up your quad, not while out riding.

Extremely cold temperatures could have an impact and a real honest danger. I've only heard about it, I've never actually seen it. If it is REALLY cold outside, and you are constantly moving, the cold air hitting the front of the engine can actually prevent the cases from warming up, and this keeps the engine oil cold. Like I said above, cold oil doesn't circulate, it's too thick. This prevents your engine from getting proper lubrication. But this is only a danger in REALLY cold temps, and a simple shield in front of the engine to act as a wind-break can fix this issue.

Aside from that, no problems. Your engine produces it's own heat, so the outside air temps generally doesn't affect it very much.

[250X_project]

Good post, Wilkin. Thank you.