New guy questions

[Mistertwoo]

So I am new and have read and followed lots of tips on here so far but have a few questions. I have a HPI 4.6 Trophy Truggy, I have run 9 tanks of nitro through it, broke it in and believe the high speed screw is properly set. Every time I try to slow down the idle speed it kills the engine before reaching the point where the clutch is not engaged and then is un-startable until I either hold the throttle or increase idle speed. I don't really care if it has a high idle speed unless it will shorten engine life.

My biggest concern is that it is eating $8 glow plugs. The first went part way through tank 5 and I thought that might be due to the excessively rich factory settings used for break in. But another appears to be shot (does not light all the way to the end) after tank 8. One thing I did different after tank 8 was put after run oil in the cylinder. I am using 20% nitro.

How long should a glow plug last and any tips on making them last longer?

I also am curious if I can just refill the tank and run it again or do I need to let it cool off first?

 

[gavin28]

If you have a good tune, a good plug will last a while, I have 2 OS#8's that are over 2 gallons old and still going in 2 different engines.
Though when breaking an engine in it is common for plugs to blow early due to the rich tune etc.

If you can't get the engine to idle without the wheels spinning, you either have a lean tune on the LSN or you have a clutch problem such as broken shoe or weak spring(s).

I would recommend 25% nitro (VP Power master is my favourite) and OS#8's for that engine.

 

[bobaloohoo]

So I am new and have read and followed lots of tips on here so far but have a few questions. I have a HPI 4.6 Trophy Truggy, I have run 9 tanks of nitro through it, broke it in and believe the high speed screw is properly set. Every time I try to slow down the idle speed it kills the engine before reaching the point where the clutch is not engaged and then is un-startable until I either hold the throttle or increase idle speed. I don't really care if it has a high idle speed unless it will shorten engine life.

My biggest concern is that it is eating $8 glow plugs. The first went part way through tank 5 and I thought that might be due to the excessively rich factory settings used for break in. But another appears to be shot (does not light all the way to the end) after tank 8. One thing I did different after tank 8 was put after run oil in the cylinder. I am using 20% nitro.

How long should a glow plug last and any tips on making them last longer?

I also am curious if I can just refill the tank and run it again or do I need to let it cool off first?

I'm running 30% champinship blend nitro with 8% oil with OS8 cold plugs, this setup seems like it sticks to a tune a lot easier and likes to tune more easily. just switched to this setup yesterday and can already tell of a drastic power increase over 20% along with easier tuning. seems like the 4.6 favors 30%

---------- Post added at 3:28 PM ---------- Previous post was at 3:27 PM ----------

and it also sounds like you dont have any pinch left in your sleeve.. BUT, first try to lean your LSN a little to get it to start, it might try to be pumping too much fuel in when its not revving high

 

[Nitro Nerd]

It's normal to blow a plug or two during break in. Very normal. I say that so you don't start chasing rabbits, sealing your engine, buy a new engine, etc. etc. when it is most likely just your tune. ;-)

Do you mind walking us through how you tuned your engine (step-by-step)? It's really important to rule out your tune before doing anything else. And yes---you should mind if you have a high-idle..not for longevity but just don't settle. We can get you going with a nice tune. .

 

[WinnersCircle]

So I am new and have read and followed lots of tips on here so far but have a few questions. I have a HPI 4.6 Trophy Truggy, I have run 9 tanks of nitro through it, broke it in and believe the high speed screw is properly set. Every time I try to slow down the idle speed it kills the engine before reaching the point where the clutch is not engaged and then is un-startable until I either hold the throttle or increase idle speed. I don't really care if it has a high idle speed unless it will shorten engine life.

My biggest concern is that it is eating $8 glow plugs. The first went part way through tank 5 and I thought that might be due to the excessively rich factory settings used for break in. But another appears to be shot (does not light all the way to the end) after tank 8. One thing I did different after tank 8 was put after run oil in the cylinder. I am using 20% nitro.

How long should a glow plug last and any tips on making them last longer?

I also am curious if I can just refill the tank and run it again or do I need to let it cool off first?

Your glow plug should last a long time.

I think you have your top end mixture too lean and your low speed mixture too rich.

I always set my low speed mixture and idle speed before focusing on the high speed needle. Also, I recommend a HOT or MEDIUM plug because they are 1) easier to tune and 2) much more robust regarding long life.

Start your engine and let it warm up a bit. Then turn in your low speed mixture. After a few seconds the idle will probably speed up. Turn the idle speed down and then turn in the low speed mixture again. Continue this process until the engine shuts off. You know that you are now too lean on the bottom. Open the low speed mixture 1/2 turn and reset the idle speed and now it is time to put your vehicle on the ground and set the high speed.

If the car smokes a lot and won't go fast it is too rich and the high speed needs to be turned in 2 hours then re-run the car. When you get close on the mixture start making 1 hour adjustments.

If the car starts to accelerate ok and then bogs it is too lean. Turn the high speed mixture out 1 full turn and try again. If it smokes a lot and doesn't go fast then you need to start turning the high speed mixture in 1 to 2 hours at a time.

Be patient and you will get it.

Good luck,

Lee

 

[Mistertwoo]

Thanks for all the responses. I bought a gallon of 20% nitro! obviously it don't want to waste it. Should I just use the rest or is there something I can add to increase the nitro %?

The way it is tuned now is per the HPI book. Turned high speed 1/8 turn at a time taking engine temp until it reached 220 - 230 deg F. Not sure how many turns before I stopped. Then tried reduced idle to point engine shut off, and backed off a little so it would run again. Book recommended not touching low speed unless you knew what you were doing and were trying to get most power... So I did not touch it

As it is set now it smokes at full throttle, seems responsive at low speeds and fast at high speeds. Engine stays below 220 for about 7/8 of the tank with continuous on and off full throttle then is over 230. I am using a medium plug.

What is LSN? Low speed needle?
What is pinch in the sleeve?

 

[Nitro4910]

The LSN(idle circuit) is what you use to set the mix in the Idle circuit on the carb.

Pinch is the resistance you feel when you turn the flywheel over by hand, these engines do not have rings like your car engine does, the piston & sleeve are tapered & get tight at the top(the pinch) to create the compression.

When you here someone say their engine has no pinch left, that's what they are talking about.

 

[Nitro Nerd]

Thanks for all the responses. I bought a gallon of 20% nitro! obviously it don't want to waste it. Should I just use the rest or is there something I can add to increase the nitro %?

The way it is tuned now is per the HPI book. Turned high speed 1/8 turn at a time taking engine temp until it reached 220 - 230 deg F. Not sure how many turns before I stopped. Then tried reduced idle to point engine shut off, and backed off a little so it would run again. Book recommended not touching low speed unless you knew what you were doing and were trying to get most power... So I did not touch it

Keep your fuel. It's your tune. As winner's circle said you are lean on top rich on the bottom. Additionally, your gap is too smal. What book are you referencing where they said not to touch the LSN unless you know what you are doing? That makes little sense.

Start at 14:06 here. It's very basic but will give you and idea of the base tune for an engine.

I've run 20% in my F4.6 for four gallons. I've also run 25% and 30%. The fuel% is not your problem. You can go through your clutch, get new fuel, etc, but I'm telling hyou.

Do this:

1. Increase your idle stop via the screw 1/2 turn.
2. Lean your LSN 1/2 turn (assuming you have yet to touch it).

A nitro engines tune is all about LSN/Idle-gap.

Finally, your glow plug should indeed last a long time...but it's common...VERY common for one to go out during break in. I've broken in ~20 engines and lost about 5 plugs during that time. It freaked me out at first too. Now I change plugs after I break in.

Remember, LSN/idle gap. Once you have it running to where ti doesn't stall, don't touch a thing for at least one tank. Then you can tune your engine. Right now you are just trying to keep it running.

 

[Mistertwoo]

I am talking about the HPI manual that came in the box. I will be able to try these this tune tomorrow. While I am tuning should I be taking it easy or is ok to go full throttle?

Also should I let engine cool between tanks of fuel or just refill and go as long as temp is ok?

 

[WinnersCircle]

I am talking about the HPI manual that came in the box. I will be able to try these this tune tomorrow. While I am tuning should I be taking it easy or is ok to go full throttle?

Also should I let engine cool between tanks of fuel or just refill and go as long as temp is ok?

Go full throttle and it is not necessary to let the engine cool between tanks. Simply refill the tank with the engine running and continue with your tuning.

Once the low speed mixture is set I rarely ever have to change it but weather changes will require that the top end mixture be adjusted some but not much. I rarely have to change the high speed mixture more than about 2 hours.

Lee

 

[Punisher]

If you are eating plugs it's your tune = you are lean.

 

[Mistertwoo]

Ok I am fighting keeping it running. I increased the idle speed and leaned the LSN. the result was a very high idle so I tried to tune the LSN per the video looking for smooth strong acceleration with smoke. I leaned out the LSN until the engine died and then turned it back a hair to get it to run again. I did notice performance gains but idle was higher now than before. I slowed it down to the point engine stopped, increased it a little and tried it. The acceleration is strong and smooth but at no throttle and no brakes it is moving pretty quick. It is also hard to start and starts easier if I squeeze the throttle a little. It frequently dies if I bring it to a stop for more than a second or two.

My understanding is it is not too lean as long as it produces steady smoke at full throttle which it does. But I see conflicting information about it being lean b/c it is eating plugs. It has not eaten another plug yet. Re-reading all of this the major thing I did not do was set LSN and idle with wheels off the ground. I know it is not tuned right, where should I go now?

Thanks again for all the help.

 

[Alexander_0_1]

I got this off ERCMs website, I hope it helps you, it did the trick for me.

Performance Tuning Guide

There are many ways to tune a nitro engine but I figure this is the most simple way to do it. This technique is for a fully broken in engine that is ready for a full performance tune. This tuning procedure will set your needles to where they need to be for optimum performance, the engine will tell you all you need to know.

For this method to work the engine has to be at running temperature (or as close to it as possible) as well as having the standard 1mm gap for the carburetor opening.

High Speed Needle

Pull a full throttle pass a couple of times and listen to what the engine does when you let off the throttle. If the it drops right to idle, the HSN is either good or on the rich side. At this point you can lean the HSN in 1/12 turn increments until the idle seems to hang a little after a full throttle pass. If it starts to idle high after a pass it is just on the lean side of a perfect tune. Back the HSN out 1/12 turn at a time after a wot pass until the engine drops right to idle after a pass. Now your HSN is set.

An explanation to what is happening is simple - if your HSN is too lean, after a full throttle pass when you let off the throttle the engine is still lean causing the idle to hang and idle high until the LSN has a chance to take over and meter the right amount of fuel to bring the idle down to normal running speed (given the LSN is set correctly).

If the opposite happens, after a full throttle pass when you let off the throttle it drops to a good idle right away and then starts to idle back up too high, this is a sign that the LSN is too lean. If it comes off full throttle with a good tune and will drop RPM nicely then the HSN is metering the fuel properly but once it hits idle the LSN being too lean will quickly take over causing the RPM to go back up.

Low Speed Needle

Most of this setting was explained above but there are a few little tricks you can use to make sure the LSN is adjusted perfectly. We all know that you don't tune for temperatures, but a temperature gun is very handy for this part. After some full throttle passes with the engine good and warm, bring it in and let it sit for about 10 seconds. At this point take your temperature gauge and hold it as steady as possible on the head, what you want to see is the temp dropping a degree every 4-5 seconds. You want the temp to drop very slightly at idle because when your off throttle the engine should be cooling, if not, the temps will keep pushing higher during on and off throttle running and will cause temperature issues.

This is how I do it and I have tuned a lot of engines for people, whether bashing or racing. I have seen across the board from beginners to veterans that when they hear the high idle after a pull, the first thing they go for is the LSN when in fact it is the HSN causing the issue. If you have any questions feel to contact me at [email protected] .

 

[nitrojedi]

Ok I am fighting keeping it running. I increased the idle speed and leaned the LSN. the result was a very high idle so I tried to tune the LSN per the video looking for smooth strong acceleration with smoke. I leaned out the LSN until the engine died and then turned it back a hair to get it to run again. I did notice performance gains but idle was higher now than before. I slowed it down to the point engine stopped, increased it a little and tried it. The acceleration is strong and smooth but at no throttle and no brakes it is moving pretty quick. It is also hard to start and starts easier if I squeeze the throttle a little. It frequently dies if I bring it to a stop for more than a second or two.

My understanding is it is not too lean as long as it produces steady smoke at full throttle which it does. But I see conflicting information about it being lean b/c it is eating plugs. It has not eaten another plug yet. Re-reading all of this the major thing I did not do was set LSN and idle with wheels off the ground. I know it is not tuned right, where should I go now?

Thanks again for all the help.

So real quick here...but 1/8 turn tuning increments is far too much movement..You will never have any success trying to tune like that.........Whoever wrote those tuning suggestions should have their fingernails pulled out with pliers for the unnecessary frustrations they must have caused so many users over the years LOL.........Anyways tune by the width of a human hair , or basically 1/24th of a complete needle turn...Basically just enough movement to nudge the o-ring.........The closer a nitro engine gets to its tuning sweet spot the more sensitive the needles will become....The further from a perfect tune the less sensitive the needles will become........

Now when you say killing glowplugs are you crunching the coil wire ? or will they just not relight after they have been run in the engine ? Also what type of glow ignitor do you use ?

what glpwplugs ? what type of fuel ? what is the oil content ?

How big is your idle gap ?

 

[hamz9561]

Another way to think of needle adjustments is thinking of an analog clock and moving the needle in 1-hour increments.

 

[Mistertwoo]

Thanks again for all the help. No more 1/8th turns for me! 2 glow plugs that were eaten have a darker color at the end where the filament touches the body of the plug and when light by igniter it only glows part way up the coil. The plugs provided by LHS are O.S. #8 using Byron Race Fuel Gen 2 containing 20% nitro and 12% lubricant also what is available at LHS. I don't know my idle gap but based on info here and talks with LHS I will check that next along with proper throttle linkage adjustment. Next I need to listen for idle hang after WOT and adjust high speed needle. Then alternate leaning LSN and idle until engine dies and bump back up a bit. Did I interpret that right?

 

[Alexander_0_1]

And you wanna see if you engine temp drops while your not on the throttle, so don't forget the temp gun.

 

[Mistertwoo]

Despite all of the help that has been provided I am still apparently doing something wrong. I tried to adjust LSN and idle gap but could not bring idle speed down without stalling engine. As I was adjusting when it would die I could only get it running again by holding the throttle. When I could keep it running the temp would climb above 250 until I shut it down. In an effort to start over I tried to set all three screws back to factory settings. But all the detail that is offered in the HPI manual is the screws should be flush but that is not even close to precise as I can go a full turn and it still looks flush. And no, I did not know before tonight that I should have already counted the turns from bottom from factory. It also appears I have burned through the 4th plug as the last 2 do not light all the way to the end of the wire (what is the correct name for that?)

I don't have a clue what to do next and I am not thrilled about going through 32$ in plugs.