Please help with nitro

[iphong]

I just got this Trinity Next and having lots of difficulties with it.

I am totally new with nitro, owned the Baja for awhile and quite fimiliar with it. I thought nitro was the same to gassoline but it's actually more difficult than I've thought.

First when I got it, I didn't know how to start it at all 'cause i skipped the manual. there is no prime bulb, no choke and I don't even know where are those HS needle, LS needle and idle screw. Finally figured out how to prime fuel to the carb and get the engine started. After 3 tanks of breaking in, the engine runs great. Very good acceleration and speed.

After 15 mins, I took the car back to home, and disassembled the engine. I was just curious how nitro engine works. After I put everything back together, the engine worked fine, but it's difficult to start at this point. Usually took me quite awhile to get the engine started from cold. But once it started, everything worked fine, great acceleration and speed.

The next day, took everything off, cleaned the carb, the piston and sprayed it with WD-40. Went out to give it another run. Again, it very hard to start at first, but this time, once the engine started, the idle was very high and as soon as I attempted slower idle, it stalled. Also, the car increased speed at about 40% of the throttle, and beyond that point, the engine got slower and even shut off if i hold full throttle long time. I even felt like there is fuel streaming from the air filter hole when I applied full throttle (I could feel it by putting my finger 1 inch from the hole). Also, I see very little to nothing of smoke but there is lots of oil coming out from the exhaust, It could wet anything sits in front the the pipe. I adjusted the LS and HS both way, but it did help, returned to factory setting (2 1/2 turns HS, 2 turns LS) still didn't work.

I don't know what problem with it, need some pro helps here. Feeling really lost and don't know what to do.

Until now, I am still not sure which is the low speed needle, as far as I understand, the image #1 is the High Speed needle, the image #3 on the right is the Low speed needle but i am still not sure what the screw on the left of image #3 and the one in the image #2. Can someone point it out pls.

 

[olds97_lss]

How far apart did you take it? Did you take the piston out? You may have put it in backwards. I'm not kidding. Typically there is a cutout in the skirt of the piston and I believe the cutout should face the crank shaft.

1 - HSN (high speed needle)
2 - in the center of the throttle barrel, LSN (low speed needle)
3 - right is idle stop screw, left is the carb cinch bolt that keeps the carb in.

I've put a piston in backwards and it caused the issues you describe.

One other thing, if you took the head off the engine, did the shim between the head and crankcase fall off? It's a thin brass washer that makes a seal between the cooling head and piston sleeve.

 

[FastEddy]

The LSN looks as if its all the way in. I "believe" it should be backed out till its flush with the outside edge of the body housing.

 

[iphong]

I didn't took the piston off the engine, just the head and the back plate. And the shim is still there.

The LSN looks as if its all the way in. I "believe" it should be backed out till its flush with the outside edge of the body housing.

Oh is it? If the screw at the throttle is the LSN then everything is screwed up. I screwed it all the way in. Could be the low speed needle is set too lean. If so, the damn manual is totally wrong. It said the right screw on the image 3 is the LSN. If my engine got damaged I think I can get my whole engine replaced.

Ok I will try reseting it and see if it solves the problem. Also the thing called idle stop screw, what should I do with it? screw it all the way in of what?

 

[iphong]

Ok, I openned the LSN 2 turns out. It's still very hard to start, but once it starts, it seems to run smoother and better but shut off easily. Are all nitro engine so difficult to start? or is it just me having problems with starting it. Do you know what problem newbies usually face when getting started w/ nitro? It took me quite awhile to start the engine. It's so much easier with my Baja, just choke it, pull a few times and un-choke and it starts right up after 2 or 3 pulls. I am so tired with this nitro.

 

[rocknbil]

In addition to the above comments, a few things I spot right off:

... I am totally new with nitro ... After 15 mins, I took the car back to home, and disassembled the engine. I was just curious how nitro engine works. After I put everything back together, the engine worked fine, but it's difficult to start at this point....

While this is common practice for those who have been doing this a while it is generally a mistake for someone new to the hobby. You probably knocked the needles out of whack and in addition may have introduced an air leak at the backplate or carb base which will account for some idling and running problems. Also it's really easy to get spec of dirt or dust at the head where the shim meets the sleeve, this will cause compression loss here too, and it will run funny. If your troubles persist, remove the backplate again, clean it up with wood alcohol, and seal up the mating surface with a **tiny** but of high-temp silicone sealer. It doesn't hurt to apply a bit around the base of the carb, too. TINY bit. Re- position the head making absolutely sure it's clean of any foreign matter, and use the cross-bolt method of torquing the bolts so it's torqued evenly - don't tighten them too tight, they WILL break.

Again, it very hard to start at first, but this time, once the engine started, the idle was very high and as soon as I attempted slower idle, it stalled.

You need to read around here about tuning. You usually tune the high speed setting first, adjust mid/low speed next, then set the idle last. If you were lucky enough not to get an air leak from dissasembly, it is most likely a simple tuning issue and it's not all that easy to learn without being shown.

I even felt like there is fuel streaming from the air filter hole when I applied full throttle

Never ever ever ever run a nitro engine without an air filter. Not even when testing (search here will reveal why.)

Just as a note here, one of two things were probably happening at this point. The engine keeps running by the vaccum created by the movement of the piston, which makes a suction at the air inlet. It's possible you only THOUGHT you felt it blowing out when in actually it was sucking air in.

If it was actually blowing fuel out of the air inlet, it was probably running way too rich (i.e. flooded) so it was splashing out, or the low speed needle was so rich it was causing excess fuel to splash out. It's usually pretty hard to keep an engine running when it's that rich, but you never know.

 

[iphong]

Ok, i took the engine apart, re-assembled everything. Also cleaned it up to make sure their is no dirt at any contacting parts. I opened LSN 1 1/2 turn out and the HSN 2 1/2 turns out. Got the engine some new fresh fuel, it started with easy with 2 pulls. engine idle high at first and wheel spinning like crazy, but when i close the LSN 1/4 turn, engine idle slower, and wheel didn't spin anymore. I rev the engine and it accelerate smoothly, and there was a lot smoke that I have never seen before (it never had smoke in acceleration before i reallized where is the LSN). Rev it a few times and the engine ran great, but when I hit brake, it suddenly shut off. I attempt to restart it, but no matter how I pulled and primed engine, it just didn't want to start. I kept on primming to get it half way flood, then I put on the glow heater and pulled again, the engine sound like it fires for 3 or 4 cycles but could get it to really start. I kept pulling like crazy, like 50 - 60 times, then it started again. The same thing happened, everything was fine if i hold it idle and rev it, but when I hit brake, it died. After engine stalled, again, it's very difficult to get it to start back. I repeated pulling many many times, then the engine started again. Then the same thing happened. After the thrid time, I was so impatient and very tired with this car so I gave up. Help pleassse... really want to get this going. Are all engine this hard to start. Should I get new engine?

With nitro, as far as I understand, the High Speed Needle delivers fuel through out the throttle and the Low Speed needle only delivers fuel at certain points (such as 30% - 100%), am I right? If so, it's completely opposite with gas engine right? I still don't get used to the nitro, I think gas is still somehow better.

 

[HeartBreak]

You have an idle stop screw that needs adjusting on the carb. Visable in the right-most picture, just under the fuel line. Turn that in about.... 8th of a turn, that should be enough to help you keep the motor running.

 

[RushRC]

Lots of good info here

You mentioned a priming bulb so I thought I would add some info.

Hold you finger on the end of the exhaust OR (with the filter removed) on the carb. This will cause fuel to force inside the engine and prime it. BECAREFUL not to flood it or you may get hydraulic lock or a very wet glow plug.

Also check the glow plug igniter and make sure it is getting the plug good and hot (glows bright red)

Good luck,
Jessie

 

[rocknbil]

... Rev it a few times and the engine ran great, but when I hit brake, it suddenly shut off.

To elaborate on Heartbreak's post, which is the most likely suspect -
With all electronics ON and the motor OFF, remove the air filter. Check the throttle trim on your transmitter and make sure it's almost all the way to the "brake" side. Now work the throttle and look in the carb opening, when you apply the brake you should see a sliver about the size of a credit card. If you do not, turn the idle screw in until you do.

PUT THE FILTER BACK ON and restart the engine.

Should I get new engine?

No you should continue screwing up - I mean learning on - this one.
This takes time man. Nothing wrong with your engine. After you "get it" you'll laugh at how difficult it was for you at first.

With nitro, as far as I understand, the High Speed Needle delivers fuel through out the throttle and the Low Speed needle only delivers fuel at certain points (such as 30% - 100%), am I right?

Yes and no. The HSN controls ALL FUEL going into the engine - but think of how it's drawn in: by the vaccum created from the movement of the piston.

So when the engine RPM's drop, the vaccum that draws the fuel drops. The proportion of air to fuel required to run properly is different. The low speed setting doesn't actually control the fuel flow - it is a bar that moves closer to the fuel inlet and slows it down to prevent flooding at lower RPM's. So you have it backwards - the low speed needle affects fuel mixture from idle to mid-speed.

I still don't get used to the nitro, I think gas is still somehow better.

Only because you know how gas works. The cool thing about these engines is their simplicity. But for the simplicity you have to apply a little knowledge and endure a learning curve. Secondly, the fuel-to-power ratio is much higher than gasoline, and you don't need a charged plug to keep it running. Hang in there, in a month you'll love it.

 

[iphong]

Ok. I got the engine started easily when it's cold. I left the car sitting still a few hours, then brought it outside. It started right up after a few pulls. I left it idle with the tires not touching the ground. I also adjusted the idle screw to slower the idle speed. It stayed on for like a minute or 2 then it automatically shut off. After shutting off, the engine became very difficult to start. When I pull the Pull start, I felt that it's much easier to pull than before. it didn't fire at all no matter how I pull it. I took plug out and it's very wet and oilly. I cleaned it and put it back, engine still dead, didn't fire up. Tried all kind of stuffs, clean plug, suck fuel out of the carb and re-prime, still no hope. Everytime I took the plug out, the plug is very wet but when I put it on the glow starter, it still glowed bright orange. After 10 - 15 mins of trying, the engine finally started up. But again, it ran for like 1 or 2 mins then automatically shut off. The same thing happened, very difficult to start. Repeat everything then it started after 10 - 15 mins. again, shut off after 2 mins.

I really tired with nitro. my hand's pain now, but gain a bit more muscle


So what is standard HSN and LSN settings for all engine, I've read many places and I don't really get a fixed conclusion, some says the LSN should be 1 turn out, some says 2 1/2 turns out. And the HSN is around 2 - 3 1/2 turns out. So what setting is the most likely safe?

 

[HeartBreak]

There really is no end-all-be-all setting that is universal. Altho, what I do is set the needles to flush and work down from there, my OS's are much different (stock on those are 1 and 3/8ths turn from closed) from my HPI and XTM motors.

On yours, the manual should list the settings.

As to why it is not easy to start, it sounds like it is loading up during idle, which is normal behaviour for nitro engines. You could try opening the throttle about 10% or so; that might make it a little easier to start. I have to do that with my savage from time to time. Close the throttle back down once it fires.

 

[iphong]

Yes, i said I tried all kind of stuffs means open half throttle, open full throttle, open a little, re-prime etc... but nothing, it only starts up after like 10 - 15 mins.

 

[Big Dan]

When you broke it on did you do it to the specs of the manfacture? You may also check to see if your one way bearing is bad. When you pull the pullstart does it pull freely or does it grab everytime you pull it? That may be the reason it is not starting right away. Also you can prime the carb with a little fuel to get it started, Just take off the airfilter put a little fuel in the carb and put the airfilter back on. Then try to start it. Does it turn over everytime you pull the pull starter? Once you get it running run it rich and see how that works out for you. Just don't run it too rich. Hopefully some of this will help.