Losi 8 427 Engine Trouble

[Nitro New Guy]

Ok So I am not brand new to the nitro thing but new to the Big Block Nitro thing ( 1/8 Scale ) I am having a heck of a time getting the engine not to flame out when I pull full throttle. I have leaned it out, richened it out, I have changed the glow plug, i have changed from 15% to 20% nitro and still does the same thing I am getting to the point where I am to frustrated to even try to get it correct.

I funny part is if I ease the throttle to full it does not bog out ! go figure LOL if anyone can help I would really appreciate it

 

[Alexander_0_1]

* Set your needles back to factory settings, if it bogs while full throttle, then the HSN is way too lean, and your running the risk of damaging that engine, this might be the reason for the erratic idle/tune you seem to be chasing, since there is too much air and not enough fuel in the mixture, example: have you ever run a nitro out of fuel, while its happening haven't you noticed the RPM skyrocket, this is what you've tuned your engine to do constantly. Since the engine is starving for fuel it struggles through the power band, causing the bog/hesitation

* The slow throttle movement you've been using is cheating the tune with maual input, you shouldn't have to cheat the carb to keep the engine running/perfoming.

* If the engine bogs/floods/stalls when you let off the throttle, and won't start right off, then its usually one of two things. A) your LSN is too set too rich. B) your carb-slider closes off the air.

* BB carb-sliders are normally set to .5mm-1mm gap, or from fully closing off.

* Remember a BB will sound different (less RPM) than a SB, since SBs almost always rev higher (higher RPM). If you've been listening to primarily SBs, then you just have to teach your ears what a true BB sounds like.

 

[Nitro New Guy]

I will be setting all needles back to Factory and following your suggestions I will get back to you and tell you how things go. Thank you for the fast reply to my Problem !

 

[Alexander_0_1]

Sure, just keep in mind were not out of the woods yet!, let us all know what happens next. We'll go again from there.

 

[Nitro New Guy]

Ok Guys here is the update ! I have reset the needles to Stock positions and now she will not start! what am I doing wrong here ? I have saved and wrote down the previous setting cause it atleast Idled pretty good. What would your next step be ?

 

[Rolex]

Lean the LSN the equivalent of one hour on a clock dial and try again. Make sure your ignitor is fully charged and your glow plug is good.
If, after several attempts nothing changes, lean the LSN another hour and repeat.
At some point it should start to sputter and try and that means you're getting close.
When it DOES start, let it idle till it gets fully warmed up. You might have to adjust the idle screw at this time. Start to give it a little trigger with the nose pressed up against something. Do the final tweaking and blip the trigger till it responds well. That's when the LSN is set.
Now move on to the HSN and start to drive it and lean it for WOT.
On a regular basis you'll have to make small adjustments to the HSN for humidity and ambient temps, but the LSN should be good.

NOTE:
The needles are like water faucets. Open is richer, closing leans them.
Turning the idle screw IN raises the idle and opens the gap.

 

[Alexander_0_1]

I'd check to see if its flooding, then a fresh glow plug is what I'd try next. Then I suppose I'd check the igniter battery strength. Adjust your throttle trim to open your carb slightly, or pull the trigger slightly while trying to start the engine.


Better yet what he said!

 

[Nitro New Guy]

Very awesome help there thank you I will start doing just that little at a time see when it fires up.

 

[Nitro Nerd]

I too am fairly new to the BB thing (well, the nitro in general) but have had this happen a few times as well. There are a number of things that can cause this, below are some things that fixed it for me:
1. Tune. Are you certain you have it back to stock? I ask because have seen documentation that is incorrect when it comes to stock settings (specifically with the Mach engines). Perhaps if you have a picture of it new you can reconcile that against the manual?

2. Tune (again). How long before it dies? Does it happen every time you go WOT...or after the engine is warmed up? Ensure your HSN is not too lean. Also...when you set everything back to stock settings, did you include the idle-stop? That could be the problem for it flaming out...and now that you've richened it up also the problem it is not starting. Try opening it 1/2 turn.

3. Fuel. It happened to me once with new fuel. Unsure if it was bad, improperly stored or what, but i tried same brand/% from another bottle--problem solved

4. Fuel lines. Ensure there is no pinching or holes. Are you running stock lines? If so make sure the inside diameter is not too small.

5. Tank. Check the cap seal on it, clean out the clunk, etc. This was the most common reason for me.

I imagine it is your tune...as noted, be sure to also open your idle gap some when going to stock...this could solve all your problems. Of course when re-tuning it you'll want to lay down the idle. Finally, I know you are getting conflicting information, but I kind of do the opposite of Rolex in that the LSN/Idle stop is what I tweak most often...where the HSN is very rarely. Just saying if the engine needs it, don't be afraid to modify any of it.

Out of curiosity, what else do you run. You're profile says you are sponsored by Losi (or were). Good to have more racers on here. ;-)

 

[Reddog]

Just out of curiosity, have you checked for a bad O-Ring or a leak in a fuel line? Little things cause big problems with these engines, so before making any adjustments I always check that I do not have any leaks- fuel or air. Shaun

 

[Nitro New Guy]

Ok what I found out is this, My motor is hanging up ! I have found that one of the clutch shoes was hanging up. Can this be causing all that problem ? Just asking . . .

 

[Alexander_0_1]

hanging up? Like it was still touching the clutch bell when it was stopped? If "yes" then it should have stalled out you engine when you let off the throttle, since the engine would have slowed to a stop along with you driveline/tires.

 

[Nitro New Guy]

hanging up? Like it was still touching the clutch bell when it was stopped? If "yes" then it should have stalled out you engine when you let off the throttle, since the engine would have slowed to a stop along with you driveline/tires.

Yes its slows down but does not stall all the time. will hold an idle and then not hold an idle its frustrating.

 

[Alexander_0_1]

I would change them out to see if it stops the issue, but I would also do the C.B bearings, and the clutch shoes , you must be generating heat from having a clutch shoe in constain contact with your C.B, no to mention the power loss.

 

[Reddog]

Another thought.. You may want to check the front engine bearing as well. As Alexander mentioned you must be generating extra heat. That may have caused a negative reaction there as well. If this bearing is bad or leaking air your engine may be hard to tune. Shaun

 

[Nitro Nerd]

Perhaps some background would also help..is it a new engine? What clutch setup? How did you verify that a single shoe is engaging at neutral? This vehicle doesn't run that crappy Losi 2-shoe, does it? If so, Does the engine start easily?is the exahust emitting unbirned fue? It would look like it pissed in front of you. I would just hate to see you incur expenses in the event it is simply your tune.Assuming you feel on you ARE ALSO confident in your fuel delivery system (including the fuel)? it can do some funny things. Not dismissing the fact it could be your clutch (they do funny things too if not setup correctly/maintained) but I've run in to this a lot and it was always either the tune or (more common) the tank, the clunk, the fuel lines. In fact, it's become a maintenance item for me. I'll put on a fuel delivery system two gallons--minimum. It's like changing bearings....it will work without cleaning them, but damn there is a difference when it's like new. ;-) I see guys on here go gallons without changing clutch bearings, fuel lines, etc.

Sorry for so many questions, but this helps me learn as well so curious how you validated this. Assuming you have a vented bell and/or see something deformed in the clutch setup?

 

[Nitro New Guy]

Just out of curiosity, have you checked for a bad O-Ring or a leak in a fuel line? Little things cause big problems with these engines, so before making any adjustments I always check that I do not have any leaks- fuel or air. Shaun

Checked And All good on the rings

 

[Nitro New Guy]

Its Ok All the questions are for the greater good in help so Your answeres are below. If you have anymore questions I mean any I am willing to answer !


..is it a new engine?
No its not a new engine its been with me for a while.

What clutch setup?
Its an Aluminium Fly Wheel ( BLUE ) 4 shoe clutch, 2 Composite ( Gold Springs ), 2 Aluminium lightened Blue ( Black Springs )

How did you verify that a single shoe is engaging at neutral?
I found one shoe ( Composite ) was melted

Does the engine start easily?
It takes a little effort to starte it ! Some work but it will fire up.

The exahust emitting unbirned fue?
Its spits A decent amount of raw fuel when at Idle.

(more common) The tank, the clunk, the fuel lines. In fact, it's become a maintenance item for me.
The tank is Solid and the seal is good. ( Checked by Submeged testing ) The Clunk Its New now. Fuel Lines are brand new. As you said these things are regular maintenance for sure.