Whats a "good" idle??

[Phins Fan]

Associated 4.6


Just tryin to get a solid tune going as I have leaned out my lsn to what I feel is pretty good and the hsn seems to still have a solid top end with good smoke and temp (240ish). My newest issue is trying to hit some type of a continual idle. Any thoughts??? I just replaced the flywheel and while apart "sealed" the engine with high temp rtv. She is used to running pretty rich on Odonnells 20% and has had a smidge less than a gallon thru her. Any thoughts would be appreciated

 

[2revo1maxx]

A good idle is one that can sustain itself for at least 20 seconds, and you'll notice the engine cooling down.

After 10 seconds you should be able to nail the throttle and have it launch hard with no hesitation or bogging.

It also has to be low enough to keep the clutch from trying to engage.

 

[Rolex]

A good idle would be slow enough where the car doesn't creep and doesn't spit raw fuel. If you hold your finger near the exhaust you should get a light misting of oil.
While it's idling to warm up, occasional blips on the trigger will keep the system clean. It should idle without stalling out. When it's warmed up and you punch the trigger it should respond with a good launch...no sputtering or shutting off.
Your temp sounds good. The idle screw and the LSN work together on the idle. Once that's right the HSN will still need some tweaking to account for humidity and ambient temps outside.

 

[Phins Fan]

So should I attempt to go leaner with the lsn? When started it will idle without issue. Once I've run about a tank of fuel and hit the brakes for a temp check is where she will give me idle issues and I have to keep bliping her so she wont stall. It almost seems erratic and "sputtering" but I dont think thats the right verbage as she will get up and go once I give her a squeeze of the trigger.

 

[moe7404]

i was told by a realy good racer. a good idel is when it idels for at least 3 hours to 6 hours. with out dieing.

 

[MotoGod]

Who is going to test their idle by letting it idle for 3-6 hours? lol I mean seriously....

Yes, a good idle should keep the car running as long as their is fuel in the tank. This means your tune is spot on or very close to it, but timing is irrelevant. If it dies after 10 seconds....it's off. If it dies after 30 seconds....it's off. If it dies at all....it's off. From a racing perspective. If you are bashing, you typically want a richer tune anyway so it may only idle for 20-30 seconds before loading up and needing to be cleared out with a throttle blip.

 

[MotoGod]

I don't know if this video will help, but it's my Buggy idling on the box at a fairly good idle.

[ame="http://www.youtube.com/watch?v=mlwA2_On_kU"]Ptm f850 at idle - YouTube[/ame]

 

[2revo1maxx]

I'd have to think that maybe Moe meant seconds or minutes.
Moto's buggy is doing what's known as a 4 cycle idle. It's fine as long as it works on your particular engine. Some engines need a higher idle than that but you should always shoot for the lowest possible while retaining good idle and throttle response characteristics.
If it stays idling at temp AND responds well after 10-20 seconds then you're doing good.

 

[MotoGod]

I'd have to think that maybe Moe meant seconds or minutes.
Moto's buggy is doing what's known as a 4 cycle idle. It's fine as long as it works on your particular engine. Some engines need a higher idle than that but you should always shoot for the lowest possible while retaining good idle and throttle response characteristics.
If it stays idling at temp AND responds well after 10-20 seconds then you're doing good.

I think it's actually the tone of the pipe you hear It's got a distinct tone for sure....

 

[moe7404]

the guy that told me 3 hour and 6 hour, is a very good racer. at one race he won some of the first heat races. he got bored and ran the last two heat races with a electronic truck BACK WARDS, and won. i am sure one or two hours would get a good outcome. he was SURE a few minuets isnt enough.

 

[2revo1maxx]

I think it's actually the tone of the pipe you hear It's got a distinct tone for sure....

Not doubting your skills at all buddy, it's just what mine sound like when they 4 cycle idle. My os 18 does that and it responds very well.....I can't get it to idle reliably any other way.

 

[MotoGod]

Not doubting your skills at all buddy, it's just what mine sound like when they 4 cycle idle. My os 18 does that and it responds very well.....I can't get it to idle reliably any other way.

What skills? I'm a hack with a screwdriver! haha

 

[TRXaddict]

A good idle is a constant smooth idle thats not hoping up and down or sounding rough. You want an idle that just has a very solid rpm and sounds like it can idle forever not to low but not to high..

I recommend just messing with that idle screw.. when you car is sitting and you hear the throttle/brake servo buzzing. you wanna adjust your th trim untill the buzzing goes away. after that you want to only touch the idle screw. And if you want that good start up off the line from idle the lean that low speed till your engine starts cutting out then very slightly make richer adjustments to the screw and youll have a spot on running vehicle.

 

[2revo1maxx]

Leave the throttle trim at 0 and adjust the linkage first. Once the linkage is set right you can fine tune with the throttle trim.

The low needle and idle screw work together. If you touch one you'll most likely have to touch the other.

 

[MotoGod]

The low speed needle and the idle screw have 2 completely separate purposes. 1 adjusts fuel/air mixture...the other adjusts the carb opening when no throttle is applied. So they both work to achieve a good idle, but they don't really work together (technically).

As you lean the engine, yes the idle will increase and in turn you will need to adjust it back down....but I rarely ever touch my idle screw once my base tune is set.

 

[TRXaddict]

Low speed doesn't typically determine idle, it will if you lean the crap out of it or richen the crap out of it but fine tuning it should just help it when there is that first amount of opening on that carb to keep from bogging from idling to wide open conditions.

If anyone is tunning the low speed for idle conditions its not the thing you should mess with. Its strictly for accelerating or launching off the line to get up to speed. when adjusting idle i just mess with the th trim and the Idle screw. sometimes the HSN because that determines over all how much fuel is going to the carb in the first place. but my personal advice is when your throttle servo is buzzing your trim needs to be adjusted to where its not buzzing anymore then adjust the the idle if needed.

 

[2revo1maxx]

That's true they have seperate purposes....but chances are you will need to adjust both to get a proper idle.

 

[HPI-Killer]

If you hold one eye open and put it in front of your exhaust stinger while its idleing, and it burns like a son of a bit**, you have a great idle,

 

[MotoGod]

If you hold one eye open and put it in front of your exhaust stinger while its idleing, and it burns like a son of a bit**, you have a great idle,

hahaha

 

[HPI-Killer]

^^ I did that by mistake on my GT2 today, and yeah it burned like a son of a bit**...

Then took a mouthfull of nitro trying to clean the lines, that poop makes ur mouth tingly and numb haha