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Message started by MnSpring on 06/17/14 at 17:13:56

Title: Start Low RPM/ Hot High RPM ?
Post by MnSpring on 06/17/14 at 17:13:56

OK, Know, idle should be above 1000 RPM,
(For Correct Oil Flow)

When starting cold, (Ambient Temp, about 60-70 F)
Idle is 800-900.
(Have a little shim I just insert to pick up idle)

When it is warm, (First Stop sign about 3 miles)
Idle is up at 1050 +/-

Any tips/tricks, ???

Or just keep doing the, 'shim', on start up ?

Title: Re: Start Low RPM/ Hot High RPM ?
Post by Serowbot on 06/17/14 at 18:12:38

Use the choke?...

Title: Re: Start Low RPM/ Hot High RPM ?
Post by Dave on 06/18/14 at 05:13:06

Yep, they always idle a few rpm lower when cold. The oil is thick, the fuel is not atomizing well, fuel is condensing on the cool intake port....etc. This is not a fuel injection system with a mass air flow sensor, oxygen sensor and a computer to adjust idle speed....it is a primitive carb.

You can pull the Enrrichent know out a notch - or just use your throttle hand to keep the idle up a bit. I start my bike, keep the idle up around 2,000 rpm until the cylinder head reaches 100 degress (30-40 seconds), then let it idle down and click it into gear and ride away very gently for the first mile or two. There is no reason to sit and idle for long periods, and there is no reason to open the throttle fully until the engine has properly warmed up. Clutches tend to slip when the oil is still cold and thick.

Title: Re: Start Low RPM/ Hot High RPM ?
Post by doctorpc on 06/18/14 at 06:02:44

My 06 S40 idles bout 1250 too high? i was always told higher is better than lower

Title: Re: Start Low RPM/ Hot High RPM ?
Post by Dave on 06/18/14 at 06:57:12

That is not horribly high. You will have better oil flow at those speeds. The only downside is if you ride in 95 degree stop and go traffic and spend a lot of time sitting still.....a higher idle will make more heat.

Title: Re: Start Low RPM/ Hot High RPM ?
Post by MnSpring on 06/18/14 at 07:30:37

5244534E56434E55210 wrote:

Use the choke?...

In Minn, 60-70 F is plenty warm. and ICE's do not need a choke or fuel enrichment. (Besides, the choke does not raise the idle speed 300 RPM).
I'll just keep using a shim.

Almost bought a place in Ajo AZ, Great in the winter.
Couple of years ago, went their in the summer,
(last week July, first week Aug).
And 120 is 120, I don't Care that it is a 'dry' heat. ;D
http://tomradde.com/az/page0/files/page0_1.gif

Title: Re: Start Low RPM/ Hot High RPM ?
Post by justin_o_guy2 on 06/18/14 at 08:43:32

I always played w/ the idle adjust to compensate for that. Id fire it up & run on choke, then 1/2 choke & be off the choke in a few miles. Then at a stop Id reach down & twist the knob & jack the idle up till it sounded right. At each stop Id adjust it down as it warmed up. Usually it was finished changing in under 15 minutes,, But, a "right" cold idle = ( for mine) a way high warmed up idle. & Keeping the "warmed up" idle setting meant a dangerously low cold idle, so, I messed with it,, Part of the charm of these bikes, I never was bothered by it at all.,

Title: Re: Start, Low RPM/ Hot, High RPM ?
Post by MnSpring on 06/18/14 at 15:32:43

Well I did a very, 'Hi Teck' mod.

Took a bit of, aluminum out of the junk box.
Cut a piece about 1"x1/2", ( It's 1/8" thick)
Drilled a little hole in it. Attached a bit of, 'string'.
(Rather substantial, 100# test braided fishing line)
Looped it around, the gas line.
(No Mom, it won't cut the gas line)

Now, to start the bike, Turn the throttle,
insert the, 'shim', turn the key, and start.
While it is warming up, (at a higher idle)
(It's at about 1250-1300)

{Don't need no sticking choke when it is 70F} ;)

Put on the helmet, jacket, go down the gravel drive slow,
(don't move the throttle, about 11 MPH)
Then hit the tar, turn the throttle,
and the little shim just drops out, and hangs their.
One way it's 3 miles to a stop sign, Idle is just fine.
the other way is about 1.5 to a stop.
A 'little' throttle if I have to wait. and then it perfect.

I have set it at about 1050 - 1080 RPM

Title: Re: Start Low RPM/ Hot High RPM ?
Post by Tocsik on 06/18/14 at 16:10:07

I'm glad you posted this, MnSpring. Mine acts the same way where cold start rpm's are too low, even on choke. But, if I adjust the idle speed to compensate, it's too high once it's warmed up.
Makes it hard to keep the oil circulating unless you keep a hand on the throttle while gearing-up.

I may have to copy your idea of the throttle shim or some variant.

Title: Re: Start Low RPM/ Hot High RPM ?
Post by MnSpring on 07/17/14 at 08:17:11

Hi Tocsik,

Sorry it took so long, but here is a photo,
of my, 'High Teck' mod.

As soon as I turn on the throttle,
it just falls off and hangs their.

I would adjust the idle to where you want it, when the engine is warm.
Then start with a 'shim', that is to thick, and just sand/file it down to what you want.

Make sure you secure it, with something substantial.

Title: Re: Start Low RPM/ Hot High RPM ?
Post by Serowbot on 07/17/14 at 08:30:42

Congratulations,.. you just reinvented the "enrichment valve", or what we commonly refer to as the choke...

Title: Re: Start Low RPM/ Hot High RPM ?
Post by MnSpring on 07/17/14 at 10:05:14

Well, pulling out the choke, did increase the RPM's
but not as much as I felt was needed.
And the engine, just did not, 'sound', the same.
as it did when, 'just', increasing the RPM's
not changing the air/fuel mix.
But, perhaps their is something, that is not, adjusted correctly.

And this little, gismo, just raises the rpm,
not change the air/gas ratio mix.

Used to be, one had a, 'choke',
and a, throttle cable. (Extra, to a foot or hand operated one)
So I guess I am just applying old learning.
Think, Tractor, Truck, Combine (that was a pull type and had it's own ICE), and lawn mowers, garden tillers, snow blowers, chain saws, log splitters.

To start, all those items. Choke, (when it was needed)
by temporary changing the air/fuel mix.
When started, increase the throttle, and push in the choke.

Of course their are exceptions.
I have a 'Pro-Line' out front Toro lawn mower.
(a 16 hp Kawasaki). It starts, Every Time, with 2 pulls.
(But only with choke on, no matter what the ambient temp is)
Choke on, pull slow, then rewind, pull fast, and it starts.
But, if I, try to start it, with NO choke, even when it is 100F,
it may take 30 pulls. Soon as it is running, choke off, throttle up.

And when it is 0, and I start the Log Splitter,
As soon as it starts, (5.5 hp Brigs, 3-5 pulls)
I have to, 'feather' off the choke, while increasing the throttle.

Seeing as how, I didn't need any choke, (on this S-40)
and didn't want to keep my hand on the throttle.
I do this. Put the shim in, turn gas/key on, start.
(two revolutions it starts), put on a helmet, and jacket,
Coast down the drive. (rough gravel go slow), Then hit the Tar.
At the Tar, I have taken over the RPM adjustment with my hand.

On the little XT-225, choking, (even when it starts without it, when above 50F)
Significantly raises the idle speed.
So with that one, it's gas/key on, choke out,
Then when I hit the Tar, choke off.

Title: Re: Start Low RPM/ Hot High RPM ?
Post by justin_o_guy2 on 07/17/14 at 19:26:19

It's alawnmower motor.. Jack the idle up and slowly drop it AS it warms up. It took me at least 10_12 minutes of riding to get it right. It's not a problem or a bother, really. The adjustment is easy to do without even looking.

Title: Re: Start Low RPM/ Hot High RPM ?
Post by Dave on 07/18/14 at 05:10:36

I get my helmet, gloves and all my gear on, then I start up the bike. Mine takes the choke to start when cold - then within 10 seconds the choke comes off and I use my throttle hand to keep the idle up around 2,000 rpm for about 30 seconds to get the oil moving and help the bike warm up. Then I let the engine idle back, click it in gear, and ride off slowly. The first 2 miles of my ride are back roads and I ride calmly as I let the engine oil, clutch, piston and cylinder warm up and get ready for the ride. By the time I reach the highway my bike is warmed up and ready to go....there is really no reason that my bike needs to sit and idle when cold. In my mind it is better to ride off calmly and let the engine warm up slowly...than it is to let the engine idle at low rpms and low oil pressure while sitting on the kick stand.

Dave