low speed usually equates to poor low end performance with possible temp spikes and a very high idling that pushes you through the corner .

high speed usually equates to an out of balance feel when running and and much less engine life due to low lubrication flow on throttle .

:blush:

or just look at post #1 ;):weird:

so it's more damaging to an engine with a lean HSN than a lean LSN...:sweat:

thats what i said in this post ;)http://www.rctech.net/forum/6090701-post77.html

Hahaha, i forgot what thread i was in! :)

newbie
 

hi guys

ive just got my frist buggy and me knowing nothing about tuning i'd thought ill ask what will happen if the car is

lean on bottom and what will the car do???
rich on bottom " "
lean on top " "
rich on top " "

or what should i look for.

as i really dont wanna stuff my motor


cheers

i bought a losi 8ight 2.0 rtr buggy when they first came out and i have been racing it for a month and half. i still have the stock losi 350 engine in it and has great power and seems to run great.

my problem is when it flames out or runs out of fuel, it is nealy impossible to get it to restart until it sits for a while. it temps at about 250 when its 90 outside. i'm wondering if the metal carb could be causing vapor lock because it does not seem to be insulated from the block. thanks for the help.

speed freak your too lean on bottom when you flame out hot and its hard to start there is not enough fuel richen your l/s an hour or two and you will find it better

rich will burble lean will hesitate then quit engine should idle smoothly and return to idle after throttle snap. If engine continues to rev after idle snap it is too lean richen the l/s needle if engine bogs and burbles after snap it is too rich on bottom. If engine idles but won't rev has lots of smoke and burbles it is rich on high speed needle if hesitates and revs to a screaming pich it is lean may even stall just quick pointers I recoomend getting someone with experience to help you at local track or hobby shop.

after a high speed pass, my engine will idle slightly higher; however if i blip the throttle, it'll return to normal idle.
if i don't blip my throttle, it'll return to normal idle after about 5s.
my guess is the LSN still abit lean? :weird:

No, actually it's a bit rich....
Lean it a bit, and lower your idle....

Because of the rich LSN, you had to set a high idle setting, after a high speed pass, the engine is fully cleaned out, and then running a high idle until it loads up again....

+1

Lean it out a touch and re-set your idle!

In this method it mentions that if you blip the throttle and the engine idles high for a few seconds then drops (which my engine does) then you should lean out the LSN until it idles high for 20 seconds, then change the idle screw appropriately. I'm going to assume screwing in the idle screw opens the carb more (which my carb does do from my observation) and hence if i want to decrease idle i should close the carb ie undo the screw. Let me know if this is right philosophy please

Also, after changing the idle screw via this process... do you keep the LSN as is? or do you readjust the LSN depending on smoke/performance again, now that the idle is set properly...

I'm a total novice to RC so yeah... please help out a young'un :)

Cheers

Hi

Run the engine for a tank of feul to get everything hot. refuel the tanks and do a high speed pass come back in and check the lsn by listening to the idle if it idles high and then drops you have a rich botoom end and should lean the LSN by 1 hour turning it in (Clockwise).

Do another full speed pass bring the car in and listen to the idle again you will notice that it still high idles but not for a long. Keep doing Full speed passes and continue to lean the LSN until the idle stays high.

now with the engine still running turn the idle screw to the left (Counter Clockwise) you will notice the idle speed drops. Set it so the idle is nice and smooth and sounds constant the clutch should not be engaging.

once you have done this the LSN and idle is tuned and you dont need to touch them.

last of all check the HSN and tune accordingly beause your rich bottom end could be hiding a lean top end

Hope that helps

Ben

so the ideal case is that after a high speed pass when you bring the car in, the engine should drop to normal idle immediately?

yes the idle will always stay the same no rise no drop

Thank you for the info BenXB8ec. Really appreciate it mate !

just bought a rossi .21 and broke it in.. i'm having trouble understanding the damn thing (i can't find the lsn)... let alone running it.. anyone know where i could find some pictures or videos?:confused:

Rossi or Novarossi? Both have extensive information about the engines on their websites.In both engines, the low-speed needle is in the end of the slide valve, nearest where the throttle linkage attaches.

Here is a VERY good video:

http://www.youtube.com/watch?v=oSmMz...eature=related

According to that, if you will leave the engine idle more than 20 sec it will stall?!

One other very important factor that has been overlooked is a NS coated cylinder has a specific texture which acts as a surface to hold oil which allows less ring contact with the hard surface, similar to cross hatches on a cast iron cylinder.It acts like a skimboard..(layterms) Keeping the rings from touching the cylinder as much.Lubrication is the key.

Hi All,

PLEASE HELP ME :-)

I have excatly the same "issue" on my engien (O.S. V-Spec blue head).

Two things you must know before I describe the issue:

When I come in to fuel, I do this only with a 1/4 throttle because it is quite difficult to get in our pit lane. And the pit lane is really narrow.
That means the engine has normal idle and it is close to stop.

But when I stop the car at the track after a high speed pass it has a higher idle.
If I blip the throttle it returns to normal idle.
If I do not blip my throttle it takes 5s to 10s to go down to normal idle.

I understand that you all recommend to lean the LSN as M7H has done:
I have done this so that the higher idle stands for 15s to 20s.
And I lowered the idle.
It feels perfect after a high speed pass.
But if I blip the throttle it lowers the idle and it's really close to stop or it stops.
Same when I come in to fuel with 1/4 throttle the idle is really low and after 1 to 5 sec it stops.

Some of my colleagues told me I am to slow I shall race a bit faster this solves my issues :-)
but I hope you can recommend something better.

Thanks a lot
racer_hh

Hi.

Try a hotter plug and retune. What plug do you use now, and how much nitro?

Have you added or removed shims in the top?

Cheers

:lol:
very good suggestion... :D

Well actually, what you just described is quite normal and as suggested by Lille-bror, try to put in a hotter plug (go from 7 to 6, or from 6 to 5)
When driving 1/4 throttle through the narrow pitlane, your engine will load-up...
Maybe you can also just set idle a bit higher...

The plug I am using is a O.S. P3 (turbo - ultra hot) And yes I have added 1 shim to the head (the one delivered with the engine).

But if you tell me it is normal I give it try to use instead of 1/4 throttle short full throttle impulses.
Do you think this improves the behavior?

And I will set up the LSN like this:
The idle is for 15 to 20sec in "higher" idle before it falls down to the lower idle after a high speed ride.
This is the way you set up your idle?

Thanks in advance - come back to you when I tested it.

The plug is perfect.
How much nitro do you use? If it is 25% you should remove the extra shim and retune (you'll have to set the hsn a little richer). The removed shim will set the timing correct (not ignite too late), and your engine will become easier to tune.

The 15 - 20 sec. depends on the fuel level in the tank. If you checked it with 3/4 full tank (and when the engine was race-warm), it should be perfect.

Back to M7H: He is the champ :nod:

Cheers

:blush:

But as racer stated he's using an ultra hot plug, I'm leaning to the idea that the plug actually is to hot....
But maybe he already needs this plug to compensate for a worn engine....
It's always difficult to judge over an internet forum...

You are right it is difficult over the internet forum, not seen the engine and with a lot of ???.
But the engine is not worn. The P3 ultra hot is the standard plug for an OS V-SPEC engine. I have seen that a lot of other OS V-Spec engines have this behavior. But when you race faster the engine is mostly hot and you bump not into my issues.

And as you said it is normal - if I am using 1/4 throttle.
I will try next weekend to lean the LSN a bit as described above and to come in with short blip full throttle so that the engine is not loading up (At the moment I am on a business trip.)

Thanks a lot for you help - and even though it is difficult you have tried it and that's great.

I will post my feedback

racer_hh

When it comes to load up at low RPM range, I've some knowledge from my plane engines.

Plane engines often come with a simple muffler. These mufflers can made too much backpressure, and make the engines run too rich in the low and mid range. A solution to that is a tuned pipe which have less backpressure, and therefore makes the engines runs perfect (and of course a big power improvement).

If nothing else helps, you could try another pipe.

As M7H suggested try to set the LSN as lean as possible (just before it goes ding-ding-ding) and see what happens.

An engine should not load up.

In theory, before I put my car on the track, on the starter box, I lean the bottom (LSN) of my engines to the point they start "bogging" and then 1 step back. The top (HSN) needs to sound just a bit rich, but on the track it will be perfect. Ofcourse you first have to maybe run the car for 3 minutes or so, to get it to fully operating temperatures, but then this setting gives very good bottom response and power....
If you use your gas throttle as an on/off switch, the bottom (LSN) should be set a bit richer, but if you have a smooth throttle finger, this setting gives better engine response...

Hi, may I know this method for all type engine? I am running STS cheapo engine :D:D:D

Another question is, may I know if we run LSN on lean side and HSN a little rich side, can cause damage engine ? Thanks.

If you look at the carb in a schematic way, the HSN actually is the "main valve" of the engine. so the HSN also infects the bottom of the engine.
A Lean bottom with a rich top end, is more save then the other way around, unless you lean the top end again, but probably the engine will start bogging then....

Thanks. By the way, may I know "In theory, before I put my car on the track, on the starter box, I lean the bottom (LSN) of my engines to the point they start "bogging" and then 1 step back. The top (HSN) needs to sound just a bit rich, but on the track it will be perfect." will work on all type of engine? Thanks again.

In my experience, yes.
But always be sure the engine is warmed up completely, including the chassis of the car.....

my engine stumbles when i fully engage the throttle from idle what could this be high end rich or low end rich or lean?

Sounds like your LSN is to rich.

Let the engine warm up, then rev the engine up a couple of times to clean out any excess fuel in the crankcase. Put the car up on pit wall (if you're at the track) or on a car stand, then pinch the fuel line. If the engine stalls in less than 6 seconds the low-speed needle is too lean. If it takes longer than 8 seconds, it's too rich. If the mixture is too rich, you may also experience a considerable increase in engine rpm (hence the reason for getting the wheels off the ground), which tells you that the idle speed is too high. So, if the engine runs on for a long time after pinching the fuel line, lean the low-speed needle and reduce the idle speed. You want the engine to run 7-8 seconds after pinching the fuel line, and without a major change in engine idlle speed. It will rev up some, but not a lot, if the low-speed needle and the idle speed are set correctly.

help
 

hi i have a ofna force .26 2 needle carb and i have a problem with it stalling from idle when i hit the gas it blows a lot of smoke and then dies and is the needle opposite the slide the low speed or mid range theres no needle on the slide itself so please help

Be sure the engine is up to running temperature, then pinch the fuel line and count how many seconds it takes for the engine to stall, and also note how much the engine RPM increases. If it takes longer than 8 seconds to stall, and the rpm increases dramatically, then the low-speed mixture is too rich, and the idle speed is too high. If it takes too long to stall, gradually lean the low-speed mixture and adjust the idle speed as needed to maintain a reasonable idle speed. The clutch should not engage or even drag at idle speed. The idea is to have the engine stall in 6 to 8 seconds after pinching the fuel line.

If the engine dies faster than 6 seconds, the low-speed needle it too lean. Richen the mixture a little at a time (1 hour to 1/8 turns max) and recheck. You may need to adjust the idle speed upward a little to compensate for the richer fuel mixture.