Proper tuning for jato 3.3?

[Samael027]

How do you properly tune the engine to run its best? I've read up and watched videos on youtube and i got the gist of what to do. It seems that when you tune your engine you mostly adjust the Hsn or the idle screw but when do you adjust the Lsn? i got my jato running, it kicks alot of blue smoke but sounds a little raspy. Also it doesn't want to sit still, it still wants to move when it comes to a complete stop. I adjust the idle screw little by little but it gets to the point where its either the car will move or it will stall out. Any suggestions on how to fix this and clean everything up?

[Assassin]

Read the engine and tuning sections study it a bit

http://traxxas.com/sites/default/fil...TQi-manual.pdf

Sounds like a lean low speed. Or the servo is not closing fully at idle.

Check linkages first.

Pop off your air filter, if the opening gap at its most closed is less then .5 the gap is too small and LSN is too lean. Make the gap bigger to .5 to .7, then richen up the LSN until the idle speed lowers. Set it just above too low to stay lit. Make small 1/16 adjustments at a time, and make a few passes between adjustments. You just need to get her staying lit at idle and if you lift up the truck the rear wheels dont spin.

At this point, tweak your HSN to be a bit fat to start. Lots of smoke and slow performance, BUT stays lit, dont richen it up so much it stalls from being too rich.

This is the starting point for tuning. You simple make 1/8 turns on the HSN as long as A) you see visible smoke exiting the pipe all the way to the top, B) performance improves, and C) the engine doesnt over heat. When you dont see any gains or smoke diminishes too much, dial back the HSN 2 1/8 turns back. Your basically leaning out the HSN to hit max performance, to know your at max you need to step over the line, then step back twice to be safe.

Once the HSN is set, use the pinch test to adjust the LSN

Simply pinch the fuel line about 2 inches back from the carb to cut fuel to the engine and observe how she cuts out. We are looking to get 1 of 3 possibilities.

1) she seems to do nothing for a few seconds then starts to rev to fast building high rpm then starvs of fuel much higher rpm then idle speed. This means the LSN is too rich, and this is most probably where your going to be., make tiny adjustments at a time around 1/16 th of a turn, and drive around for a few passes between adjustments.

2) She cuts out alnost right away ( under 2 seconds) and doesnt build any rpm, she abrubtly just cuts out. This is a lean LSN, make 1/8 adjustments richening the LSN until you get the 3rd result.

3) after about a second, the rpms clime up slightly and she cuts out. Key point, rpm need to climb before cut, cut out should be inside 3 to 4 seconds, and the rpn should not climb very much before cutting out.

Read the manual, focussing on the detailed engine section.

[Desert JATO]

i wouldn't add more on what Assassin said , only you need to check that your trim dial on your radio is at zero . it's possible that the throttle radio trim being turned or adjusted by mistake.

[Samael027]

Wow thank you so much, Very informative and detailed. I wasn't expecting such a great answer, people usually get straight to the point. I do need alot of adjusting. If i pick her she starts racing a little and balloons the tires a bit so i instantly have to hit the break if i flip or what not. I Will follow your guide to a T and let you know how it goes, once again thank you so much!

[Samael027]

Quick update, I got her running good now, it's tearing stuff up now i just need to fix the idle screw and Lsn. I was working on that when my ez Start battery went dead on me. Thought i fully charged it the night before but it wasn't plugged into the wall,lol. Anyways, i did a few adjustments on the idle screw got it running ok to were it stays running but kinda jerks in place, adjusted the Lsn once and it wouldnt start then i found out the battery was dead,lol. After all the tuning the temp hit around 260-270 so i enriched the Hsn by 1/16 x 2 turns.

[Assassin]

Glad to help.

When the idle is too lean you will not drop temp at idle. You want to see a 1 degree drop every 1 to 2 seconds.

Drive around, pull in to check, if its not dropping fast enough or not at all, richen the LSN a tiny 1/16 turn then drive around and recheck. If when you richen the LSN the rpms fall to stall after driving around a bit, adjust the idle screw clockwise 1/16 at a time until after driving around she idles without dying and you get a steady degree drop every 1 to 2 seconds.

[Samael027]

now does clockwise speed up or slow down idle speed? Also thats what i was doing i would adjust the Hsn do 1 or 2 high speed passes pull it in and adjust from there and check the temp. So your saying to adjust the Lsn then adjust the Idle screw. if so i was adjust the idle screw then the Lsn.

[Double G]

As for the HSN and LSN when you are turning it clockwise you are narrowing the passage for the fuel to enter through so it is leaning out. The idle screw is different as clockwise causes the screw to push the barrel open--making the gap bigger. Generally you set the idle gap to 0.7-1.0mm open and leave it.

[Samael027]

Makes sense, I will adjust the needle putting the gap to 1mm and adjust from there. One last question, I'm sure its just guessing but how can you measure to be sure its at 1mm?

[Assassin]

Im not talking about performance. Im talking about when you sit and idle. Your adjusting the HSN and checking the temp you get to after a pass. Im talking about your idle, when your not giving it gas and the truck is just sitting. At idle, you check if your dropping temperatute, making sure you see the temperature lower 1 degree every second or two. You simply pull in let her sit for a few seconds then check the temp, wait a second and check it again, and again and again. You look to see the temp drop 1 degree every 1 to 2 seconds. IF you dont see this happening, you need to adjust your idle speed, I explained how to do this, but only if you have to.

I say this because you describe a lean LSN & temps up at 270f. With a lean lsn you dont get the cooling off throttle or at idle that you need, this has temps rise even with a fine tuned HSN. If your seeing visible smoke all the way to top speed, its most likely a lean lsn getting your temps that high.

Its not wise to put it to 1mm, .5mm or .7mm and just leave it. You need to adjust the gap inside that window or not far out as the engine asks. If a set opening and never adjust would be ideal, it would be fixed and not adjustable. Temp, Alt, fuel, pipe all will play a factor in what the engine wants, we always adjust all needles as to what the engine needs. The engine is always comunicating with us, we give her what she ask for and she gives us performance in return.

[Samael027]

I believe i did have a lean Lsn I tried the lsn test by pinching the line. It instantly cut out, as soon as the line was pinched it died without doing anything. unfortunately i had to stop tuning as there was a bad storm coming in. I tried starting it up and do a little more tuning before the storm hit but it wouldn't start. I would prime it through the carb and it would start instantly and then die a second or so later.
I was planing on setting it to 1mm and adjust from there. I'm going to set back to factory settings and tune from there.

[Assassin]

If you richen up the LSN 2 1/8 turns, it shiuld be good to tune from. Reset and you need to tune from scratch, kinda a last resort IMO, as we know what your engine wants in its current state.

Your pinch test confirmed my thoughts, just follow the steps I posted to fix a lean LSN.Sounds real close.

[Samael027]

Ok, Thank you. You been been helpful, as always! I'll post back if i encounter anymore troubles

[Samael027]

Update: I got th jato tuned pretty good, Nice top end speed and idle's perfectly. After getting everything tuned up i hear a long clinging noise sounds like metal, im not sure what this is ,doesnt sound good.

[Assassin]

Get some audio, wheres it coming from? Engine or gear box? Can you hear it at idle or only whel you rev up, and did you check your clutch shoes and bearings, if not check them.

[dustyfingerz]

I followed this and got her runnong great

[dustyfingerz]

Whats your 2nd gear set to I put a 56 spur on wondering whats the best shift setting for street and dirt with bigger tires

[Assassin]

Good to hear its been helping out. I may put a dedicated tuning guide up if I can find some time to get it done right and as simple easy reading as possible to help the widest range of Nitro Burners.. Lifes a little swamped now so Ill do what I can.

[Samael027]

Hey guy's, I've been really busy and the past few times i tried to check the forums, it just wouldn't want to load for me. Anyways, I'm not quite sure where it's coming from but it may be the motor, and its when i'm idling i mostly hear it. I have not checked my clutch shoe's or bearings. I'll read up on how to do so.

Edit: I just watched a video online on how to replace the clutch shoes and spring, it seems pretty straight forward and will probably replace them sense i'm sure they have not been replaced yet. I also tried to capture sound but it just sounds all blurred together, you cant hear the clinging noise.

[Assassin]

Check the clutch, spring might be streatched and a shoe wobbling or something. Teally hard to say without audio, give it another try someplace quiet and post up even if you dont hear it, we might hear something from the way shes sounds.

[Samael027]

Ok, Ill post them up, as i said its pretty poor audio. Im uploading the videos now, ill have links in a few minutes.

Sound 1
http://www.youtube.com/watch?v=5Jj02s-U0cY

sound 2
http://www.youtube.com/watch?v=-4QR1Lgsvpg

around 5 seconds in you'll hear my ringtone from my phone, so ignore that =).


Lsn test
http://www.youtube.com/watch?v=p_9NY4SPM4U
I know its a little lean it cuts out fast just wanted to kinda to throw as much sound your way as i could.

[Assassin]

Tok tok tok. Think I hear that in Video 1.

Hard to say. Might be experiencing detonation from a lean LSN. You want to pinch check after you get the HSN tuned up to make passes up to speed with smoke, then after a pass, pull in to pinch test. Your lSN is lean back that sucker up. Get het lit as you do then gradually back it out listening to the engine, listen for the ping to stop. Then tune the HSN, followed by pinch testing/tuning the idle.

I would clean up the OWB and inspect the clutch shoes, spring & bearings. I would also look in to inspect the con rod, and remove the cooling head to look for signs of detonation. it will look like little dings or dents, alot of detonation and you will see quite a bit of dents, look like somebody hit it a bunch of times with a center punch. You will see it on the top of the piston & on the cumbustion chamber.

[Samael027]

Dam assassin, i just watched the two videos of your more recent post on drilling out the stinger, Your jato's engine sounds so smooth compared to mine. I thought mine was decently tuned. My engine sounds really rough compared to yours.

[Assassin]

Might be pinging from a lean LSN.

I forgot to mention take a peak at your carb gap, it might be too small.

Uncorked shes as smooth as silk, but a handfull.

[Samael027]

I checked my carb gab and its about 1mm give or take. I read somewhere on the forum 1mm gap is around the size of a paper clip, So i found a paper clip and adjusted the carb gap by gauging with that.

[Samael027]

Ill take everything apart and clean it out and inspect it then go and tune the hsn and the lsn and by OWB you mean one way bearing?

[Assassin]

Pop out the glow plug, get the piston at TDC for a sec, then look in at it with a flashlight. You would see lil dings on the top of the piston. Thats a quick check. Remember to put it back at BDC (to that after every session) and clear out fuel when done.

I would give tuning the LSN more rich, see if the ping stops. Then get on the HSN & when its set, pinch test/tune in the LSN.

Firstvsteps, check the idle gap is not too small and get that LSN richened up.

Yes, OWB = One Way Bearing

[Samael027]

unfortunately i miss placed my 5/64 allen key, so i cant open it up and check the OWB, but i can check the piston. Probably a stupid question but how do i set it a TDC and BDC? Sorry for all the questions and really really appreciate all the help you have given so far, i'd be completely lost with all the help.

[Assassin]

Its all Good Bro, here to try and Help.

Under the truck you can access the flywheel. Rotating it, it will get tight near TDC and free up around BDC. After a run wait a few min then rotate it with your finger till it feels free. An easy trick is lookinh in the glow plug hole to adjust it to BDC then use a sharpie to mark the flywheel, then you can just adjust the mark to the bottom.

Allen keys often strip in the screws or strip the screws. Hobby tools hold up and work better. The sets are expensive, but you can grab one at a time, they make life a bit easier.

[Samael027]

I got a few nice hobby screw drivers from a friend for rc cars that are really nice but unfortunately as you know the 5/64 one is used 90% of the time for a jato which wasn't with the screw drivers he gave me, so i plan on just running out and pick up a nice one. Also thats a really good idea marking the flywheel would of never of thought of that,lol. Would make adjusting it super simple for future use.

[Samael027]

I took off the cooling head and cleaned it and inspected the piston and the sleeve for dents, I didnt see any dead at all. The piston was a little gunked up so i used a alcohol wipe to clean it up at TDC i put it to BDC and sprayed some wd-40 into it and the carb and rotated the fly wheel a few times. I also cleaned the cooling head and sprayed it with a foam degreaser. I then rinsed the head under hot water to wash it off and wiped and air dried before i installed it back on. I may know what is causing the noise. I took out the OWB when i was cleaning the jato and i may have installed it back on the wrong way.

Also sense im going to replace my clutch shoes for sure, would it be better to replace with and alloy shoe or replace with the similar clutch that's already in there.

[Assassin]

Alloy shoes, but a backwards installed OWB and she shouldnt start. At least there was no detonation, thats good. In the future dont rince the engine with watter ever. Use fuel to rince it, if you dont intend on running it right away, clear out the fuel and put some after run oil in and turn her over a few times.

What did the clutch look like?

[Samael027]

I usually clear out all the fuel and run her till she wont start anymore then spray a short 1-2 second burst of wd-40 into the engine and a short 1 second burst into the carb and turn it over a few seconds and install glow plug and now ill put it at BDC. Is there any type of cleaner i can use to clean the engine instead of fuel? Its quite expensive to use furl for cleaning,lol. The clutch looked good, heres two pictures maybe i missed something. The spring was still tight and didnt seem loose in anyway.

http://i1270.photobucket.com/albums/...820_145423.jpg
http://i1270.photobucket.com/albums/...820_145411.jpg

also what brand of after run oil would u recommend as im sure thats better than wd-40.

[Assassin]

Thats a little excessive. The fuel nowardays has ARO in it so WD-40 and ARO os not needed after every run. Judt clear it out of fuel like you do and blow it with some com.pressed air. After every half gallon to a gallon hit it with the WD-40 as you do after cleaning the engine and blowing off debri. Clean your filter religiously.

Clutch lools good. Interesting seems like everythings in check, no smoking gun. Its easier when there is something standing out broken. Check the gears in the ezstart. Nothing standing out.

Use ARO to lube rebuild, but its easier to start up after when fuel is used in my experience. Do not lube the OWB, keep the shaft and bearing dry on instalatioARO is cheap, 3 or 4 bucks, just grab what the LHS has on hand, not much difference one to another and you dont need it often, I only use it to prep for winter storage.

I have Trinity Nitro Power Final Run Solution

[Samael027]

I was cleaning the engine like that after every run because in the tutorial video's for traxxas, they said to do it when your storing for more than a few hours. When i was checking the clutch i just quickly popped out the OWB and checked it. it was on correctly and all that seemed to be fine. Ill just pull out the fuel and make sure the piston is at BDC when i put it away for the day. After checking everything and cleaning stuff up i haven't had time to start her up. I'll tune the LSN and HSN and widen the carb gap, as you said the sound may be coming from a lean LSN. Once i have it all tuned up ill get back to you. im hoping for the best!

i plan on replacing the clutch shoes in the near future with alloy ones and looking at some better shocks. What upgrades in general would you recommend for the jato?

[Assassin]

RPM bumper and arms, 7075 T6 Chassis, Alloy/rubber/bearing wheeliebar wheels, batt pack mid ship, ERCM pipe, vantage or tsais header. Engines Nova 2.5 or OS21TM

[Samael027]

Sounds good, That Ercm pipe looks badass. What did you mean by batt pack mid ship? Also are piggyback shocks good? My jato seems to bottom out alot even at low jumps. I have the shocks as stiff as they will go.

[pbflash]

Sounds good, That Ercm pipe looks badass. What did you mean by batt pack mid ship? Also are piggyback shocks good? My jato seems to bottom out alot even at low jumps. I have the shocks as stiff as they will go.

If you're using a flat battery pack, it can be installed in the middle of the chassis. There is a battery box just to the tight of the clutch bell. The only piggyback shocks I have seen reviews for are the Integy ones and the reviews were not good. Have you tried a heavier shock oil? I think they come with 30wt stock. A heavier oil will give better dampening.

[dustyfingerz]

i put 40 in my stock shocks and changed the placement of the shock connection to the innermost position and can jump descent sized jumps with no dragging the dirt but do still plan on upgrading the shocks make sure to tighten the cap of your shock with your wrench or theyll just pop back out just dont over do it

[Samael027]

Ah i never noticed that battery pack case. So that would eliminate the need for the rear case 4 AA's which would be quite nice. Ill probably just get a heavier wt oil instead of replacing the shocks. Also how hard is it to completely take apart and reassemble the jato 3.3? i really want to take it apart and give it a deep cleaning but sorta nervous to do so.