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down-shifting / coasting

Posted: Thu Jul 01, 2010 11:49 pm
by ScootLemont
if this has been covered in another thread, feel free to point me there but I did not find (using search) that answered this question clearly (or is there a clear answer?)
Again... if this is a redundant post, sorry

I live in a VERY hilly town and I am going up or down a hill abut 1/2 the time so that means I am coasting abut 25% of the time I am riding.

Should I be down-shifting or coasting in gear on my 2T Stella?
My thought is that when doing either of those, the engine is running on compression & not gas right?
& if that is the case, no oil right?
& that cant be good right?

Any thoughts on this?

Posted: Thu Jul 01, 2010 11:55 pm
by jmkjr72
on an old premix set up when you were coasting or going down hill under compression you used to be oil starved as there was no fuel flowing


but the stella is oil injected and the injector runs off the crank so if the crank is spinning oil is being pumped

depending upon the hill some times i just like to pull the clutch in

Posted: Fri Jul 02, 2010 12:48 am
by ScootLemont
thanks - you are becoming my "shell answer man" for newbie Stella questions

Just for kicks I ran the "My Tracks" app on my Android while picking up a pizza for dinner tonight.
I rode 2.28 miles (one way) and my elevation changed 121 feet (& I didnt even go downtown)
I sucked to ride a bike in this town as a kid.

Posted: Fri Jul 02, 2010 4:22 am
by Howardr
jmkjr72 wrote:on an old premix set up when you were coasting or going down hill under compression you used to be oil starved as there was no fuel flowing


but the stella is oil injected and the injector runs off the crank so if the crank is spinning oil is being pumped

depending upon the hill some times i just like to pull the clutch in
I understand the theory here, but it hasn't worked for me in practice. Here in Tucson, it is possible to ride/coast/glide downhill for many miles at a time. There has been a couple of occasions when I was doing just that when I started smelling something burning, something oil-like. Immediately after giving Stella little bit of gas (while coasting) the smell went away.

It was explained to me that if you are idling (as when going down a long hill or sitting at a very long stoplight) then there isn;t enough oil being pumped. You have to rev the throttle just a bit from time to time.

That being said, I don't know that you will ever have to worry about coasting for 5-10 miles at a time in Wisconsin.

Have a nice day. :D

Howard

Posted: Fri Jul 02, 2010 1:50 pm
by ScootLemont
yeah... the hills I am talking about are maybe 100 or 200 yards long at the most.
My thought at this point is not to worry about the smaller hills & leave it in gear (if I will be accelerating at the bottom or turning with out stopping)
But on the longer hills (like the one my house is on) I will pull in the clutch or shift into neutral for the ride down

Now... if I can just remember to use the foot brake!

Posted: Fri Jul 02, 2010 4:35 pm
by Anachronism
It is easy to clutch in for downhill sections, and safer for your engine. 2 strokes and engine braking can be a tricky situation.

I descended some 5000+ vertical feet over 20 miles with the clutch in when riding Trail Ridge Road in Rocky Mountain NP, and was never in any danger of overheating my brakes.

Posted: Wed Sep 01, 2010 1:47 pm
by JoshWED
Anachro- Can you explain the relationship between downhill, engine breaking, and 2 strokes? I stalled out last night going down a pretty significant hill in 3rd gear. Haven't been able to start her back up as of this morning...just fits and starts which I think have more to do with some vacuum issues but would like to hear what you have to say.

I'll be posting the vacuum issues under separate cover/thread...but like I said, if there's something about engine breaking and two strokes, I'd love to know. Ta!

Posted: Wed Sep 01, 2010 4:53 pm
by illnoise
A 2-stroke engine is lubricated by oil mixed with the gas. I've always been told to give the engine a little gas occasionally when coasting down big/long hills in neutral. Whether premix or injected, I don't think that'd make a difference, even with the oil injector, the oil metering is linked to the throttle, so you might not be getting enough oil at idle.

then again, i've never understood why you'd need extra oil in your top end if you're basically idling in neutral, even though you're moving faster than usual. The transmission is in an oil bath, it doesn't care.

If you're IN GEAR and using the engine to hold your speed downhill, then yeah, you'd want more oil in the cylinder for sure, though you'd want to be careful not to rev too fast.

Either way, i don't think premix vs. autolube would make a difference, since, as I said, the oil's linked to the throttle.

Bb.

Posted: Wed Sep 01, 2010 5:00 pm
by JoshWED
Thanks Ill