n00b needs help again please

[battledonkey]

I bought a brand new HPI Savage 4.6 last Thursday. I ran the 2 idle tanks and the 2 easy 1/2 throttle tanks like the manual said. Even at 1/2 throttle during break in it was trying to wheelie. So I went the LHS and bought a wheelie bar and mounted up and went to tune. And then the nightmare started.

It got very hard to start so in running the nitro start drill so much (not continuously but so many 3-4 second bursts) it loosened the 2 small allen screws that keep the nitro start receiver locked onto the OWB shaft. So I took everything apart very very carefully and (not knowing exactly what I was dealing with) had the back plate off. I made sure pin was set in the crank to grab the OWB internally, RTVed the back plate, and reassembled with thread lock. No more issues turning over.

Put a fresh glow plug in it and went back after it. I just cannot get it right. I've tried HSN first. I've tried LSN first like Rolex suggested. It just will not tune right. As it sits now it will take off and shift with smoke out the exhaust but is sluggish until the very last bit of the power band. If I try to lean out anymore it will flame out. At least that's what I believe it's doing. As soon as I let off the throttle and sometimes while I'm running around 1/2 throttle it just dies. No hesitation, no warning, just goes from running to not running instantly. I cannot get the performance back to save my life. No attempts to wheelie, just smooth but slightly sluggish acceleration until it builds enough momentum and then it will haul ass balls to the wall like it should.

Man I really need to find someone close to San Antonio to give me a hands on tutorial or make a friend at the LHS or something. Jeez. Right now if you put a gun to my head and told me to make that Savage run right I would have to take the bullet.

As always, thanks in advance for the advice and help and if there's something stupid I'm missing give me hell about it,

Doyle

 

[sgra2951]

Buddy I had a ton of tuning problems with mine as well. It takes a TON of time and trial and error to get it all figured out. You need to have the HSN level with the outer housing. Then, slowly turn it in as you run. Same with the LSN. You need to have it level. Not too much in, or out. I also had a bad glow plug, you need to make sure that its tight, not too tight but snug. This will cause issues. I hope this helps. if not PM me and we can talk more.

 

[battledonkey]

Awesome. Thank you! My plan is to use the hour or so of daylight I usually have after work every freakin day until it's right. I'll update this thread as I go and I'll PM you if needed for sure. I'm definitely looking forward to the support of this forum. I'll need it!

 

[Alexander_0_1]

Before you start tuning your engine make sure your carb slider is set properly, actually it's a better idea to check the carb slider settings before you start a break-in. Also check your trim settings make sure they are at neutral, or zero.

Your carb slider should only close to a credit card width while brakes are applied, but not close completely, and should fully open when throttle is applied, or as close as a stock servo can open under the load of the carb.

Almost everyone ends up changing the plastic/composite servo arms and linkages to alloy so to eliminate as much flex as possible.

 

[battledonkey]

Thanks! Will check it when I get home.

 

[battledonkey]

Checked carb slider. Moved pretty good. Went back to factory settings (very sure I had it right, both needles flush with the bodies they sit in) and now it mangled the coils on 2 glow plugs and has poopy compression. Was blowing lots of blue smoke still. I think I'm gonna call it for now. I'm gonna pull the engine, clean the hell out of the chassis and all those parts, and stick it in the attic until I have more time/money to mess with it.

 

[94smasher]

Sorry to hear that...but nothing will test your patience like a finnicky nitro. Sometimes a break and a fresh set of eyes are the best thing. That being said, when you say 'mangled 2 glow plugs' do you mean physically squashed the coils? If so, that's usually a sign of being lean. I'm nowhere near an expert, just trying to help. I've had to go back to factory settings on mine a couple times, and try again with the tuning....it's frustrating, but it is do-able!!

 

[battledonkey]

Ya like the coils were pushed in a little and over a lot. like a i stuck a toothpick in there and shoved it all to one side. Just tore it all down and theres 2 random knicks on the top edge of the piston. Wtf....

 

[battledonkey]

 

[battledonkey]

There's also a spot you can see on the top of the first pic where a whole edge looks scarred up. What the hell? What would have done that and is that enough to significantly hurt the compression?

 

[battledonkey]

The bottom of the dang plate the glow plug goes in has scars and chunks missing too. The "cup" surrounding where the glow plug is threaded in is peppered like sandpaper too. What. The. Hell?! I handled this thing with kid gloves just wanting to get it broken in and keep it nice. It was almost $450 after all. That's a good chunk of change for me. Anyone have any ideas?

Something burnt a hole straight through my exhaust!! Did something pass through the motor rather violently or what? Holy crap.....

 

[mrbones]

I will be interested to see what these guys have to say about this because I haven't a clue as to what would have caused all this. Did you run it without the air cleaner and something got sucked into the carb?

 

[battledonkey]

I will be interested to see what these guys have to say about this because I haven't a clue as to what would have caused all this. Did you run it without the air cleaner and something got sucked into the carb?

No sir, took the air cleaner off once when it was braaaaaand new in a clean environment on my work bench to verify the idle gap and then zip tied it back on.

 

[Alexander_0_1]

Debris could have fallen into the combustion chamber when you changed the glow plug, of course I'm just guessing.

What were the temp gun readings? The damage could be from the engine running too hot/fast, once you pull the piston/sleeve out I'd like to see if anything from the bottom of the piston fractured off causing the pitting.

Your glow plug damage is from the combustion not being centred, cause the smooth surface of the cylinder is damaged. It pushes away from the side where the pitting is, since that's where the force is trying to escape first.

The melted pipe is where said debris stopped traveling, and just melted a divot/hole where the hot exhaust eventually melted the pipe....the pipe is the reason you can't tune your engine. Two strokes rely on the back pressure of the tuned chamber of the exhaust to force your escaping fuel/air mixture back into the engine combustion chamber since they don't have valves to open and close the combustion chamber like a 4 stroke would, your fuel/air mixture would simply escape without it one.

 

[battledonkey]

What does everyone think the odds of HPI sending me a new engine are? I genuinely don't feel like this was operator error. Like I said I was pretty gentle with it. I blew the head out pretty thoroughly every time I swapped the glow plugs. And honestly, I don't believe that debris could have gotten hot enough to burn through the exhaust. I could be wrong and I'm not trying to be uppity at all, I just feel like odds are it was a faulty motor. I'm 100% open to opinions and advice so keep it coming. I guess if it won't be warrantied then I'll chalk it up to experience.

 

[Alexander_0_1]

I would definitely give HPI a call and see if there's something they'll do. HPI has pretty decent customer service. What can it hurt it's just a phone call.

Also that combustion chamber does get very hot. Once you start your glow engine the glow plug relies completely on the combustion of the engine to keep it glowing, and if the wire in the glow plug can glow hot enough to maintain combustion, then whatever caused the pitting could also have been glowing....what stuck to your button definitely had to have been glowing hot enough to melt it to the surface.

 

[battledonkey]

Well, I'll give them a call in the morning. Hopefully they'll be willing to help. It did run pretty strong during the 2 circle 8 tanks so I'm still confident in the product and want to see it run right so no matter who foots the bill, me or them, it's going to get fixed eventually. I'll update the thread as soon I talk to them. Thanks for everyone's input!

 

[rcaddic]

They mit send ya a new one , looks like it got real hot , the dots on top of the piston are most likely from predetonation happens when running 30% fuel and not shimming the head and every once in a bluemoon doing WOT runs with a bad tune .
When I tuned mine I did 3 sec pinch tune .
first set idle some where around .6mm to 1mm then start truck let warm up a bit then pinch the fuel line about 1 inch be for the carb if it takes 3 sec to die your LSN(low speed needle) should be good if it dies befor 3 sec your to lean on the LSN if it takes more them 3 sec to die your to rich on the LSN , and for the HSN(high speed needle) lean it 1/8 at a time onto you here it shift in to 2 gear , this should a good starting point , fine tuning will come after you get a basic tune down.
If you don't have a heat gun do the good old spit or water test , put a drip or two on the head if it boils your ok but if the drip just jumps right off the head your to hot = lean.
hope this helps in some small way

 

[battledonkey]

I'll take all the advice I can get. Thanks again!

 

[Alexander_0_1]

^^ what he said!^^

If HPI doesn't warranty the engine and you end up changing out the piston/sleeve combo.

1. It's as simple as pulling the engine, remove the heat sink.
2. Taking off the backplate to the point where you can see where connecting rod hooks onto the crankshaft.
3. Set your piston at bottom dead centre.
4. Fold some card board, stick the folded cardboard into the exhaust port.
5. Take your flywheel tool (must buy) grip the flywheel with tool.
6. Spin the engine until the cardboard pushes out the sleeve.
7. When the sleeve out you should have enough room to work/wiggle the piston free from the crankshaft, make a note of the direction the connecting rod was before removal, it matters for lubrication purposes.

To reassemble just follow steps in reverse.

Can you tell I like to disassemble!