582 smoother idle!?

[Olle1975]

Hello,

has anybody an idea for a smoother idle?
My engine is shaking at 2000 rpm, by 2800-3000 rpm or more it runs very smooth. Has anybody else this situation or a idea to get smoother, may be changing Idle jet?

Olaf

[Dusty]

First thing is to check your rpm is correct ,the factory tachometer is only a general guide!
Sync your carbs, preferably using the vacuum test.
I run 35 idle jets and have a smoother idle than the 55's
Warmup is still best around 2500rpm but when warm 2000 is ok
The box will start to growl around 1700!
Your idle stop screws may end up screwed right out,so check the throttle slides aren't left hanging(they should both give a dull thunk noise when closed)
You will also notice your EGT'swill be better on finals around 950 rather than flatlined off he scale,it's good to know there is a healthy fire up front if full power is needed in a hurry!

[Av8r_Sed]

What prop are you using? If it has a high mass moment of inertia it'll be tough to get it idling smoothly.

[Olle1975]

Thanks for comments!

I additionally use Tiny Tach for rpm.
The carbs are sync mechanic and pneumatic.
I use the GSC prop, it's not older than 2 years with round about 120hrs.

I run 35 idle jets and have a smoother idle than the 55's
Is the 35 idle smaller than the 55 and the Idle gets leaner? I suspect the idle has to get richer for smoother idle?

You will also notice your EGT'swill be better on finals around 950 rather than flatlined off he scale,it's good to know there is a healthy fire up front if full power is needed in a hurry!
How do you hold up your EGT during Idle in final?

Olaf

[Dusty]

Leaner for a smoother idle and higher EGT.
Rotax seems to set rich at idle, possibly to minimise the risk of getting lean if the prop is driven on descent.
This doesn't seem to be a problem with a 582 in a kitfox but maybe in another application this may change.
Be aware on your first few flights 1200EGT game over!
Also bear in mind an oil injected engine will be getting oil on a lean descent,
Premix will need some oil,so occasional throttle will be prudent

[napierm]

2nd that on the idle jets. I ran the #45 idle jets on the 582. That's with a 3-blade GSC prop on a 3:1 "C" gearbox. Engine would load up and quit on final before that. Same with extended idle on ground. Another help was switching to the iridium tipped spark plugs. The fine wire runs hotter and doesn't foul easily.

[Av8r_Sed]

The GSC prop is pretty light and shouldn't cause any problem idling. +1 on what Napierm and Dusty have said. I have a clutch on mine, so no load at idle. I had to file my carb slides and go to a 35 idle jet.

[Olle1975]

Hello,

to switch on 45 or 35 might be a good idea, thanks!

minimise the risk of getting lean if the prop is driven on descent

If you drive your prop on descent your idlejet hasn't got any task, if you would like to minimize your egt in this situation, you have to change the main jet during full throttle or the setting up the needle during 1/2-3/4 throttle.

first few flights 1200EGT game over

1200 is maximum and ok but 1150 will be better, watch at your sparks.

Premix will need some oil,so occasional throttle will be prudent

Yes, oilinjection is the better way for idle during descent. I have round about 120 hrs on my engine, it runs great by more than 3000 rpm. I will check to change my idlejet to get a smoother idle, thanks.

Olaf

[Dusty]

Maybe start with 45 jets if you are unsure.
At throttle closed it is still possible to rise the EGT by driving the prop but is unlikely to get dangerous ,with 35's I havn't seen above 1000F
I agree 1200F may be ok but the gauges we use aren't precision instruments,
A plug colour test is a good way to be sure (yours look good 1150 -1200?)
Changing your idle jets effects the lower end of the mid range jetting by a surprising amount!
By changing to 35 idle jets we are deviating a long way from factory settings
Sometimes throwing the text book out the window isn't such a bad thing

[Olle1975]

Hi Dusty,

My last sparks, works 25 hrs during winter and spring....




Yes we haven't precision instruments, my rpm gauge shows more than Tiny Tach, I hope the egt has the same behavior :-)

In which altitude do you start and fly, my airstrip has only 200ft msl?

I think, first I will srew out my idle-mixture-screw, so I get a leaner mixture too.

Olaf