Jato dies when tires hit the ground

[guardog]

The Jato will fire up nice, good fuel flow but everytime I put it on the ground and touch the throttle it dies I have installed new glo, clean air filter, fresh fuel and even cleaned out the carb. I also checked clutch bell bearings, clutch spring and OWB. Pulled cooling head and piston is perfect. Plenty of compression. I have been through the entire realm of tuning from factory settings and higher and then factory settings and lower. Pulled the HSN needle to make sure there is no damage. I don't have a clue Anybody have any ideas? next step is to try dynamite

[Mind_Reader7]

There is only two things that will cause this.

A broken clutch spring.
Bad tuning.

I'd say open your idle 1mm more, and turn both the HSN and LSN in 1/8.

[Desert JATO]

Agree. mind reader is correct. check your clutch spring then do some work on tuning.

[guardog]

clutch spring looks good. Not broken. May be possible that it's not allowing the shoes to expand when hitting the gas. Will replace the entire thing to ensure that's not the problem

[Desert JATO]

ok. update here for the benefit of the other readers.

[Jato8283]

Also, while youre at it, check your bearings. Not only for your clutch, but for your diff as well. I just recently took my clutch apart and the bearing blew apart, which in turn seemed to have thrown my first speed gear off alignment. I removed the clutch bell and the bearing parts fell out shredded, and I removed the rear diff cover and a bunch of gear teeth fell out. First gear was completely stripped. All fixed now, total of $12 fix. At least parts are cheap =)

[guardog]

It will rev and the tires spin freely when held off the ground so I doubt its any gear teeth. Bearings are a possibility. I will strip it down when time alows and keep you all posted on the results. Thanks for the input

[Nitronaught]

clutch spring looks good. Not broken. May be possible that it's not allowing the shoes to expand when hitting the gas. Will replace the entire thing to ensure that's not the problem

The spring prevent s the clutch from making contact to the CB. If the spring was too strong the clutch just would not engage and the power from the engine would never make it to the tranny... SO your wheels would not spin....

If the clutch spring was broken or stretched out, then it would idle off the ground and your wheels would be turning because the clutch has engaged the CB.. This is not your case...

I'd try a fresh glow plug,, if you've been tweaking the needles take them back to factory and start there with a new plug. Go from there...

[guardog]

Thanks Nitronauht... I know you're a guru when it comes to this stuff. However, I had a new glo as stated in my previous post. I'm using a "hot" plug and 20% sidewinder fuel. That's why I'm so baffled. Done everything I can possibly think of. I have the engine yanked out now and double checked everything. The spring is good and so are the bearings. Might have to take look at the tranny when I get time. Anymore ideas ? I know the HSN is 4 complete turns and the LSN is 1 3/4 or flush with ring. Been there and done that as well..... same results. Seemed to run just a little better at only 3 turns on the HSN but not much and I know that's a little too lean. Thanks for the help !!

[guardog]

If the tranny and everything else checks out O.K. then I guess my next option is to yank the carb and clean it with some denatured alcohol. Trying to avoid doing that as a last resort.

[Mind_Reader7]

What happens if you have the front wheels down, start it, give it 20% throttle, and lower the back down?

[guardog]

Mind reader.... I can start it on the ground and it will sit an idle perfectly but when I give it gas she dies where she stands.

[Jato8283]

That definitely sounds like the problem I was having and I stated in my previous post what I had to fix. Check the tranny, haha. My clutch bearing was shot and my first gear was toothless. Especially if youve already checked everything else you could think of. Its a pain, but it could be your answer. Hope you get her running man. No Jato should have to sit around when there is so much dirt out there. Good luck bro

[Mind_Reader7]

Mind reader.... I can start it on the ground and it will sit an idle perfectly but when I give it gas she dies where she stands.

Remove the spur gear. If you can't get it rev without any load, it an engine issue.

[guardog]

Here is some pics. Everything checked out with diff and bearings but when I fired her up she would rev up but only creep. Guess I need new piston and sleeve
s


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I am here: http://tapatalk.com/map.php?nevy0s

[guardog]

Traxxas support provided NO support. Dude didn't want to hear anything. Told me new motor is 115.00. No help at all. I as surprised. They've always been helpful before. Local shop is looking at it and gonna send it in. Not even a gallon through it

[Jato8283]

Wow dude... Thats with less than a gallon through a new engine?

[jamesaclao]

Holy crap! Thats ugly! Sorry about your engine. Have you been doing your after run maintenance?

[mattster1971]

That sleeve and piston look scortched. Did you break the connecting rod removing, if not that's obviously the reason for the failure. I had my connecting rod also break with proper breakin and running at proper temp. It started doing what yours did, then I reved it and it came off and beat the crap out of the bottom of the piston shattering it. I am mad at Traxxas for the response also only having purchased it in January. I suspect a bad run of connecting arms they used. Plus half the new engines are just rebuilt turn ins, I suspect reuse of some parts. Unfortunate

[mattster1971]

Why is your exhaust header so rusted? Are you running in water heavily?

[Double G]

Looking at the photos, there is no way that is Traxxas's fault as that engine has been run lean and over-revved. Evidence is the coloring of the top of the piston, around the piston skirt and the rod. Has the head ever been removed before and the gasket replaced? It looks like the sleeve top is scorched too and burned fuel around the top of the block.
I'm venturing to say that there is more to the story than Traxxas support not listening to you and flat-out saying buy a new engine. Did they happen to ask if you would send it in so they can look at it? Did you tell them what you found as displayed in the provided pictures?

[Nitronaught]

I was not part of your conversation, and I can understand being upset when your $150.00 engine is in need of rebuild or replacement,,, In your case I think I would just buy a replacement for $105.00 off of an Ebay chop shop....

Now, I just want to point a couple things out from the pics you provided, in which, Traxxas probably could not see, but it would defintely do you no good, there is no warranty against being ran lean, or leaks that develop causing lean or timing/tuning issues which will ruin any Nitro engine... And neither does any other Nitro engine Mfr.

Now I'm not trying to be a jerk here, but let me point out a couple things I see from your pics...

Where the head shim meets the block,,, there should be no discoloration there, the shiny aluminum should still be shiny if the cooling head was sealing properly... It wasn't, yours shows evidence of a leak. See where brownish coloring is on the shiny part?

Also I see what is called carbonization on the top of the sleeve as well as where your exhaust port is. This is a clear sign of operting temps over 300 degrees at the glow plug... It's when it is so hot that the oil which is not supposed to burn does....

300 degree + operating temps means there is too much air or too little fuel, friction is what is creating all this heat, 20,000-30,000 rpms and too much friction = conrod/piston failure... OR you will experince the loss of compression.... When you lost that compression it would run, but would not run under load,,, then the conrod was already failing but just decided to fully let go in the end...

Since you have split the rod, my concerns would be there might be debris in the journals and bearings... The cost of replacing the bearings, conrod, piston and sleeve come to as much a a new, pulled engine from ebay for $105.00


If your like me and like mechanics, upgrading, modding... then there is another alternative that I do.

Now your cooling head is good, might need a new shim (highly recommended.
Also I see some pulled Piston sleeve and conrods on Ebay for like $60.00
Then you could always get a set of Avid Ceramic engine bearings for $35.00
Head shim $4.99

Fuel porting the sleeve was my option, could be yours too.

Check your carb make sure you do not see ANY CRACKS by the HSN housing before you go spending... Could be a deal breaker....

I hope this helps, and if ANY Traxxas Customer Service Rep was unprofessional to you in any way,,,,
I'd be talking with a supervisor at that point... I've talked with them many times and since 2004 I have yet to be treated poorly ever.... Let the supervisors know, I'm 100% they do not tolerate unprofessional behavior of any kind....

[mattster1971]

I remarked that it also looked scortched. I think that the discoloration of the rod and the piston are clear indicators it was run at too high a temperature. My issue with my 3.3 is that I had no discoloration, no scortching, was running at a great mix, temps were good, no indication of problems then poof, stopped, heard a noise as I rotated the wheels, clutch not engaged, pieces loose in the engine. I took it apart to find the split rod and the piston with the skirt all smashed up. I decided to just purchase the sleeve and piston and pin and new bearings. I like working on these things with my hands and it will be a fun project. I just wish the engine had given me more than the 3 months and gallon of fuel.

[Assassin]

that looks like hyper lean runnin. What were the temps you were running that thing up to, must of been hot and past 270f...

Doubt VERY much thats after a gallon. Look at all the crud on the header. Either the gallon is bad or you drove it through all kinds of crap without propose cleaning. Been a gallon Ive been running mine and it looks showroon new...

[NitroMethaneRunninThruMyVeins]

holy shnikeys. man you straight up roasted that engine. buy a new one and tune it RICH on both needles. over lubricated engine is much better than extra crispy engine

[guardog]

Thanks for all the input. I don't have a temp gun so I can not honestly tell you the operating temps. Guess I'll be purchasing one soon. It always ran well and never any major issues until one day it just gave up on me. I usually ran at 3/12 on the HSN and flush with the ring on the LSN. Broke it in at 10% traxxas with hot plug and then recently switched to 20% sidewinder. Also used WD40 after each run in the air filter port and also in the cooling head after removing the glo. My Tmaxx 3.3 runs like a champ. I am not upset with Traxxas in any way. I own 5 of their vehicles and have always had excellent support. Guess I just caught this guy on a bad day. My local hobby shop is taking good care of me and is attempting to resolve the issue. Thanks again

[Mind_Reader7]

#1 You should not use anything less than 20%.
#2 Do not use WD40. It eats away at the rubber seals if left to long.

[guardog]

Thanks Mind reader. No more WD

[rustlernate7504]

Why do people say wd40 eats away rubber,the engine manual from traxxas says its fine to use it.i always have with no issues,then again i dont leave it in to long i drive almost every couple of days.

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