Diagnostic time (again) :(

[Mickstix]

I'm having a heck of a time getting this SH .28 to run right (at all) When we last left off I was having to lean out the LSN just to get it to idle and run w/o the glow ignitor hooked up.. Well once I did that it was showing all the signs of being too lean on the lsn.. If I richen it at all it'll struggle to take off and die as soon as it loads up with fuel.. If I lean it back out it idles so high it wants to run off.. If I goose the throttle it'll idle down for a second then right back up too high.. If I lower the idle screw it wont run at all.. What gives? It's still not fully broken in, but man, the tune is acting so erratic?? It was getting up to around 200*, but when I let it idle high (sounds like a chatter) it got up to 240 so I shut it down and put it up for the day.. (I'd already burned almost a full tank of fuel just tryin to get it to run.. I sealed the engine and carb, I wonder if I could of screwed up the carb (entroduced an air leak) somehow? I dunno, I'm about at my wits end with this thing.. Basically the only way I can get it to run and accept throttle is to over lean the lsn and have the idle WAY too high.. I've tried the HSN from a half turn rich to a half turn lean (from stock) w/o any real difference.. Any ideas?? Thanks.. :\

 

[RC Addict]

240 is still not too hot. Over 280 is. I really think you are JUST getting it warmed up to the point where you can actually get it to run and diagnose and that is where you give up. You can not properly tune an engine till it is up to operating temp. Get it running somewhere between dying out from flooding and reving too high. Then run in till it warms up. Then worry about your tune. If the only way to get it to run is to run it "over lean" then your temps will soar. THAT is the time to worry about things, not at 240.

 

[olds97_lss]

I'd agree with RCA. Just drive it. Be easy on it, but get some fuel through that engine. Worry about idling and tune later. Walk it through a few more tanks of fuel before you start to worry about the tune. You want it a bit rich and if you keep fuel running through it, it should stay cool enough to run.

Just keep at it.

In the end, it may be the pipe, fuel or plug that is causing issues, but until you get half a gallon of fuel through it, it's going to be up in the air as to what your issue is. Especially since you've done all the things we do to help with leaks.

 

[Mickstix]

OK, if what I did tonight didnt help or fix it, I'll just run it lean with a high idle.. But I took off the carb "barrel" and fuel inlet, and there was some junk in there.. Looks like residual "Delux Copper" rtv that I'd used when sealing up the engine/carb.. My carb is a little different than the one in the "sealing" how-to I was following.. My barrel/inlet doesn't use any washers or "o" rings.. It's just a brass barrel, and a plastic (ie: cheap) fuel inlet.. The only thing that seals them is how tight you tighten the barrel into the carb, and I had put RTV on both sides of the inlet, and tightened her down.. Apparently that was not good.. I dunno if it was enough to cause it to run weird but I wiped it off and flused it out anyway.. There was also a slight leak in the fuel tank cap. I could hear it "sizzle" when I'd blow in the pressure line (to prime the carb) I finally got to the big "O" ring inside the cap, and it wasn't sealing completely.. It wasn't much but it was enough to "hear", so I took the cap apart and put it back together.. Dont know how long it'll stay fixed using the same "O"ring and cap, but for now it seems to be airtight.. I'll let ya'll know how it goes tomorrow.. Thanks again.

BTW: I recently got a temp gun, and I set the "emissivity" (or whatever it is) to 77% (For anodized aluminum) Is that what I should have it set at for a blue anodized head?? Also, I point the gauge straight into the top of the head, as close as I can get w/o touching it.. Is that where I should take the reading or somewhere else for getting the max engine temp?? Thanks!

 

[Scrogg]

Point at the glow plug and right beside it... As far as emissivity....I can't help ya! Sorry bud.
Glad you figured out the problem, HSN housings are best left alone. Just tighten them down good and leave them be. Check them every now and then.
When tuning remember
idle to 1/4 throttle is LSN.
1/4 throttle and up is HSN. adjust accordingly and you almost can't go wrong.
That engine will vaporlock @ 250, keep it under 250F. It will be impossible to tune as the fuel flow will become inconsistent due to the carb neck not having a thermal shield. Find a Dynamite Platinum .21 to .28 or LRP carb. It will make the engine run better and tune easier, also make starting easier when the engine is warm.
The older cheaper SH engines did not have heat shielded carb necks, the newer ones may though. I have not touched a regular SH in a while.
One more thing, toss the glow plug...you've abused that one. It willl not tune correctly or worse, it may break off in the engine. MC-59 or O'Donnell's hot Red Sport plugs, or a 97 O'Donnell.

 

[Mickstix]

Not sure if it has a heat shield on the carb or not? (I've only messed with these SH engines, so I have nothing to compare it to) But I'll see how it goes now that I got it cleaned out.. Should be warm enough tomorrow to give it another go.. Will also scratch the glow plug!! Thanks as usual for the help!

 

[Mickstix]

OK, got to run the car again today.. (Still breaking in the motor) It ran pretty good, as far as breakin is concerned.. But the high idle is disturbing.. If I dont blip the throttle ever couple seconds, it starts making a high pitched squeel?? Is this what's known as "4 cycling" or something else? That's what it was doing the other day when it got up to 240*, but today I just kept blipping the throttle and it'd idle down (slightly), but a few seconds w/o throttle and itd be making that weird noise again. Sounds like the things in pain.. lol.. Is there a term this, or is it just a product of the LSN being too lean still? It ran ok and the temps were right around 220*, so I left it alone and finished off the tank..

 

[Scrogg]

A high pitched squeel is not good. Sounds like you got one of SH engines famous unseated main bearings and/or the crank has slid towards the back of the engine.
Check into warranty before you tear into it. Go thru globalhobby for SH engine support.
I would inspect it thoroughly, tear it apart. But that is just me.
Try richening the LSN some more and look for leaks....sometimes they can make a whistling kind of sound....It sounds like a possible bearing failure to be honest.
The idle issue sounds like you are too lean on the LSN, or your idle gap is too big.
Neither condition should make a squeeling sound though, that concerns me.

 

[RC Addict]

+1 That is a very disturbing thing...

 

[Mickstix]

To be honest, maybe squealing isnt the best description. (or maybe it is) I may try and get my camera on "video mode" so you guys could see/hear it? It'll be a few days though cause it turning cold again and it's speed weeks But I honestly dont think its a bearing or rubbing "squeal".. It's more of an exhaust note/tone I think.. But I'd still like for you guys to hear it.. I'll look into making/uploading a video.. I've alread had the backplate off to seal the motor, as well as the carb, so any warrenty claims are probably out the window.. Thanks!

PS: Anyone know where/how to upload a video? Is youtube the easiest place? Thanks again..

 

[RC Addict]

YouTube is the easiest place because, when you place the link in the post, it embeds the video.

 

[Mickstix]

OK, here it is.. Pretty easy uploading to youtube! (Thanks RC) I'll let ya know now, it's getting better as I go.. The more I richen the low speed needle (to lower the idle) the less it makes this sound.. Not sure if it's just "breaking in" or what, but I've been slowly richening the lsn, leaning the hsn, and reducing the idle gap.. Seems like after every adjustment I have to go through a few "passes" of it running like crap, then the adjustments "take" and it's ok until I adjust it some more.. Granted I'm making these adjustment in 1/16th or less, at a time.. Anyway, here's the vid.. I'd just started the car and let it idle for about 30 seconds when I started rolling the vid.. As you see at the end it just died.. Guess it wasn't warm yet, cause that was the only time it died today.. Ran a tank and a half through it, making 1/2 to 3/4 throttle passes (It's way rich on HSN still, so it boggs at anything over 1/2 throttle) but I kept the temps right around 220.. Thanks for lookin.. [ame=http://www.youtube.com/watch?v=mlRaS0kcJLg]WHAT'S THAT SOUND??[/ame]

 

[MotoGod]

Sounds like a really high idle to me. I would set it back to factory specs and slowly start to lean from there. Remember that you do NOT control your idle via the LSN. The LSN does affect the idle, but don't adjust your idle using the LSN or you will end up WAY rich on it.

I would also yank off your air filter, turn on the rig electronics and set your idle gap with the brakes on. Also make sure you have a throttle return spring on there. I had issues with my carb slide bouncing a little back open when I let off the brakes at one point. Return spring makes sure that problem goes away and acts as a mini failsafe.

I didn't really hear any bad engine noise in there though. I was expecting a god awful squealing noise! haha

 

[Mickstix]

Well.... maybe "squeal" was a stretch.. But dont you hear that odd tone it takes, when it loads up? Sounds like its in pain to me.. lol.. Anyway, thanks for the diagnosis and tips!

Edit: It just dawned on me what the sound reminds me of.. It sounds like the horn, that was about dead, on my buddy's VW bug, back in highschool.. New diagnostic question: what does it mean when your new nitro motor sounds like the dieing horn on an old VW Bug?? hehe..

 

[RC Addict]

I agree in that you have the idle WAYYYYY too high. I like seeing that blue smoke coming out of the stinger when you punch it though. Lower that idle and I think you are on your way to getting it right.

BTW--Where is your throttle trim set on your transmitter???

 

[Mickstix]

As dumb as my questions are, I truely wish it was a throttle trim or idle scew adjustment that was causing these issues.. To refresh everyones memory, the reason for this "diagnostic" thread was because the motor wouldn't stay running w/o leaning the LSN out THAT much.. If I richen it, it died as soon as I touch the throttle.. If I lower the idle screw it wont run at all. (gap is already less than 1mm) I had just reset all the needles to stock and found it wouldnt even run w/o the ignitor constantly hooked up, then I asked about leaning the LSN during breakin.. That got it to run, but the idle was sky high, and it sounded like a weak car horn when it loads up, then I started this "diagnostic" thread.. Since then I've ran a few more tanks of fuel through it, and it's starting to let me richen the LSN about a 1/16 at a time.. Any more than 1/16 and it acts too rich and dies on throttle.. Hopefully by the time I get a few more tanks of fuel through it, it'll be acting more normal, as it was coming around the day I made the video.. (But it's still in "breakin" so I'm only running it a tank at a time) But for whatever reason it only responds (positively) to these baby steps, even though it's WAY too lean on the LSN still.. I still dont know why it does that..

 

[MotoGod]

Well if your idle gap is that small you must be WAY lean on the LSN then. I would go back to factory settings. It WILL run at factory settings or within a few hours of factory. It will be rich as hell, but it's a great starting point.

I have a brandy new engine I'm in process of breaking in....and when I fired it up I had to lean the LSN maybe 1-2 hours to get it to idle normally. I then leaned the LSN maybe another 3-4 hours over the course of 3 tanks to get my temps up while idling. Once I got to tank 4, I richened up the LSN again and leaned the HSN by @ 2 hours or so...then started tuning to drive it.

Right now I'm @ maybe half a gallon with a rich driveable tune...and I'm only @ 5 hours total on both needles away from factory settings.

 

[RC Addict]

I am at a loss here. That idle gap that small yet you are getting a copious amount of blue smoke off throttle. Hmmm... Doesn't make sense. If you are as lean as you say you are (and there is no idle screw to bring down the idle) then I would have to think you have one serious as hell air leak SOMEWHERE that is throwing everything outta wack. I am stumped on this one. From the video I would just assume the idle is too high and the tune is right on on the LSN...

BTW--The ONLY dumb question is the one not asked!








































Except for Qaart...

 

[MotoGod]

Air Leak would definitely make it hard/impossible to tune as well...and lean it out enough to bring the idle up. Yank the engine and seal it up. See if it gets better ;-)

 

[Mickstix]

Motors already been sealed up, as has the carb.. Like I said, it's a mystery! Only thing I can think of, is the cap on the fuel tank has a slight leak. I can hear a slight "sizzle" sound (ie: air leaking) when I'm blowing in the exhaust line, to prime the motor.. I've had the cap apart and the "O" ring seems too big to me, but that's all I found.. (Only problem with that being the cause is, it should make it run lean when the needles are set to stock.. This motor acts RICH when the needles are set to stock?)

Moto, it wont run (literally wont even idle, unless the ignitor is hooked up) at factory settings.. I had to lean the LSN almost a full turn before it'd stay running w/o the ignitor, and not die (flood) as soon as I touched the throttle.. The LSN is definitely WAY too lean, that I know.. But it wont run any other way.. But like I said above, the last couple tanks of fuel it's "started" to let me richen the LSN, w/o dieing on throttle, but it still sputters and spits until I make a few passes, then it calms down and is ok, so I richen it a little more.. Its just taking a long time to get it there, as it'll only accept a 1/16 of a turn at a time.. I'm hoping it'll keep letting me richen the LSN, as I go, and eventually start acting normal.. The reason for the smoke is because the HSN has been richened, to keep the temps down under 240.. (Before ya say it, I've already tried it with a richened LSN and leaner HSN.. Wouldnt run) And with the HSN stock, and the LSN leaned out, it was running too hot, so I richened it to get the temps down to around 210-220.. Every time I richen the LSN now, I'm also leaning the HSN, so hopefully it'll be ok here in a couple more tanks.. I was more concerned with the actual "noise" it was making though.. As long as it's not a bearing trying to seaze up, I dont mind continuing to run it and see if it'll eventually let me tune it right..