Warming Up

[ggavin]

Hey guys,

Just wondering how long do your bikes take to warm up when the engine is cold? My 35 takes a good 10 mins ! Is that normal?

Full choke while warming up and idles just above 1k revs when started, goes to about 1.5 when it's warm. I use to rush it when I'm in a hurry by playing with idle adjuster, but have realised it is very bad for my baby so I stopped doing that .


Cheers!!

[johnnie5]

what do you define as warm up ?

warm up is as long as it takes to put the helmet and gloves on

then ride it gently

vehicles warm up quicker when used rather than left to idle

[magg]

Agree with johnnie5, long idle warmup period is considered by some in the auto industry to be detremental to long engine life. Gentle ride off soon after start up results in quick warm up which keeps the acid/water levels, generated during the combusion process, at the lowest levels.

[Neosophist]

Agree with johnnie5, long idle warmup period is considered by some in the auto industry to be detremental to long engine life. Gentle ride off soon after start up results in quick warm up which keeps the acid/water levels, generated during the combusion process, at the lowest levels.

Im with this approach.

Always start the bike up on full choke, no throttle.

Put the helemt and gloves on and ride away and turn the choke off.

You should have better oil pressure with the engine underload.

But remember, the bike will respond poorly with a cold engine so you need to take it easier and becareful not to stall.

its not difficult at all but takes a little pratice if your not used it it.

Running it at idle with excessive choke will just dirty up the fuel system and waste gas.

[speedy231278]

I start the bike on full choke and wait for the revs to pick up, which normally takes between a few seconds if the weather and bike are warm to maybe a minute if both are cold, put the choke back in and ride off shortly after. I don't like riding off immediately after starting, but at the same time I agree completely that leaving the bike for ages will more than likely do more harm than good. I won't ride off until the bike will idle without choke, however. In addition, the first four or five miles are taken sedately, and I keep the revs and throttle opening down for at least that long, and won't go much above say 7K and half throttle until the temperature gauge has started moving. No risk of me thrashing a cold engine, for sure!

[ggavin]

I posted this thread right before my exam and checked it after while I was warming my bike up ready to go home. I gave it a go, didn't let it sit for long at all, rode it delicately and my god it ran a lot smoother than I thought!!

I seem to have been very misinformed since the beginning. This has been my routine for a very long time and holy shit I thought I doing a good thing for my bike

Thanks guys your replies have all been very reliable!!


EDIT: What I use to do was turn on the choke and wait. Eventually (that's where the whole 10minute thing is from), the revs will rise quickly to about 3k, then I'd turn the choke off and ride away! I use to think that was the bike telling me it's ready

[benny]

My NC30 idles about 4-4.5k revs with the choke on, this is the process I use (Which is how I think Alex showed me!):
* Start engine with full choke, wait for revs to rise and stop about 4-4.5k
* Reduce choke by about 3rd wait for revs to be stable about 3-3.5k
* Reduce choke further, wait for revs to stable about 2.5k
* close choke, wait for revs to be stable and temp gauge to be in the blue.
If cuts out then raise by a third.

[ggavin]

Hey guys,


Did the same thing again this morning; choke on, start bike, put gear on and as soon as i put it in first the bike lunged forward a bit and cut out. I started it again in gear (clutch in start), and it ran fine. Should I be worried?

@Benny. On a cold start my bike would idle just above 1k with choke on, without choke it wont start. Unless I turn the choke on when the bike is hot I wont reach those idles. Not sure if the warming up routine is different with the 30s and 35s.

Cheers all!!

EDIT: Also I should add that the choke was still on when I put it in first, was planning to turn it off as soon as I exit the driveway. Is this incorrect?

[Ben_OB1]

Hi Gavin,

To answer your question it is probably easiest if you understand what the choke is actually doing. The carburettor is designed and set up to provide the correct air-fuel mixture during normal engine operation across varying engine load and speed conditions. When the carburettor (and engine) are cold, this is all upset as the fuel is cooler (affecting its vaporisation) and the precision mechanical elements of the carburettor are cold, making orifices smaller than when they are at design temperature. As a result the various ports/jets/venturi nozzles that meter the fuel are not correctly sized when cold to make sure that a suitable air-fuel mixture will be delivered to the engine... usually the result is a very lean mixture.

Different carburettors have different systems for delivering the "choke" effect, but essentially the choke introduces additional fuel into the inlet airstream.

The NC30/35 demands the use of the choke when starting, if you try to open the throttle too soon after starting you will find that the engine stutters and wants to stall. This is the affect of introducing more air before the carburettor is able to match the additional air with additional fuel (leaning out the mixture).

So, to answer your question, you need to have the choke on only long enough for the carburettor to warm sufficiently that the engine will respond to throttle inputs. As it warms on the choke the engine will gradually accelerate, once it has reached 4k revs or so, it will start to respond to throttle inputs. I would normally turn the choke completely off at this point, test the throttle response, and monitor the idle.

You may want to leave partial choke on to improve throttle response for the first few minutes on the road until everything is up to temperature if you can't wait for it to warm thoroughly before you head off.

Just remember that the additional fuel introduced by the choke will cause the bike to run rich after it has warmed up. Be careful that you don't leave the choke on too long (especially when left idling) as it may cause your spark plugs to foul.

Ben.

[ggavin]

Hey Ben, thanks for such a detailed reply, much appreciated !!

That routine is how I use to warm my bike up, however, it takes my bike about 10 mins in order for

So, to answer your question, you need to have the choke on only long enough for the carburettor to warm sufficiently that the engine will respond to throttle inputs. As it warms on the choke the engine will gradually accelerate, once it has reached 4k revs or so, it will start to respond to throttle inputs. I would normally turn the choke completely off at this point, test the throttle response, and monitor the idle.

that to happen. Now I am a bit confused since I'm getting different answers. Am I suppose to let it sit and wait til the revs jump? Or ride delicately until it warms up? Which is the correct routine?

Thanks all!!