Aftershock Tuning Issue

[Quinster]

I just purchased an Aftershock and I have been having problems. I set the low speed screw by pinching the hose and the revs go and then it shuts down, as is stated in the manual.

I try to set the high speed and when I get it going at medium/low speed it seems to run fine as long as I don't squeeze the throttle too much, if I do, it starts to bog down/slow down/or stall. Even at high speed it seems to bog down periodically, and again, if I don't let off the trigger it will stall.

Any help would be appriciated.

 

[Nitro Rascal]

I just purchased an Aftershock and I have been having problems. I set the low speed screw by pinching the hose and the revs go and then it shuts down, as is stated in the manual.

I try to set the high speed and when I get it going at medium/low speed it seems to run fine as long as I don't squeeze the throttle too much, if I do, it starts to bog down/slow down/or stall. Even at high speed it seems to bog down periodically, and again, if I don't let off the trigger it will stall.

Any help would be appriciated.

That sounds like the high speed needle is set too rich therefore flooding the engine when you squeeze the throttle.

 

[Quinster]

I thought so...tried many settings over a three - four test period, will try turning it back tonight.

Thanks!

 

[olds97_lss]

Check for air leaks or look at the engine closely to see if you see anything thats damp.

My aftershocks stock engine leaked out of the LSN. I took it out entirely and the o-rings seemed ok, so I cleaned out the hole with a q-tip and DA, put some associated slime on the o-rings and put it back together. No more leaks (or at least very little).

It was throwing my tune out of wack pretty badly. After I did that, the engine calmed down quite a bit and ended up being a not bad engine. Not a powerhouse by any means, but it would carry the truck around pretty good.

I did notice that mine liked running on the warm side. A hair too rich and it would get blubbery and stall when I got off the gas. So, I gave up on keeping the temps at or below 240 and tuned it to run. Temp checks would show me 260-270 average, but it ran fine, idled fine and wasn't blubbery.

The only drawback from a hot running engine is that if it stalls due to being on the roof or out of fuel, the fuel in the carb boils and you have to wait for it to cool to start it. Or, do what I did and hold the throttle wide open and give it a few quick yanks. Normally would take off then. Just make sure to let off the throttle as soon as it screams to life!

 

[Quinster]

Could any 0 - ring lube oil or grease be used instead of "associated slime"?

I am thinking of taking the engine out and going over the whole thing.

It is now surging and kicking to a high idle, and/or after acceleration holding a high idle which to me is suspect of an air leak.

Think I am on the right track here?

 

[Quinster]

After doing more reading on this site, I am convinced I will pull the engine out, clean with alcohol, seal the neck and back plate with high temp RTV and also lube all o-rings.

 

[olds97_lss]

Yeah, definitely sounds like a leak.

I used the associated green slime just to avoid damaging the o-rings. I'm not sure what you can lube them with that won't hurt them... maybe silicone oil?

Make sure to check your fuel tank for cracks and your fuel filter for a bad seal. Mine showed up out of the box with a torn fuel filter o-ring... made my first few tanks of break-in a living hell.

 

[bnrpat09]

this can also be caused by you running it too lean because the engine will heat up and cause these little power struggles.... i would suggest even though this is not what it says adjust the high speed then adjust the low speed and then finish tune the high speed one more time..... if that does not work check for air leaks like suggested above.... check on the gas tank primer button and the gas cap, check the fuel lines and then is its still not solved check all over on the engine as a last resort...

but most of the shifting and engine problems on the losi monster trucks like 75% - 80% of the time is caused by a bad engine tune.

 

[Quinster]

Engine is out, gave it a good cleaning, previous owner didn't do regular maintenance (I am pretty sure).

I am also planning to replace the tank with either a new Aftershock one or upgrade to a LST for longer run time (depending on what the LHS has in stock). Got RTV, going tonight to get the associated slime if the LHS has it.

Will let you know the end result.

 

[MrClean]

When you get your new tank, be sure to take out the primer and JB Weld or epoxy the hole on top. There is thread here somewhere that shows how to remove it. It's one less thing to worry about and from what I've heard the primer can cause all kinds of headaches.

 

[Quinster]

thanks...found the thread

https://www.rcnitrotalk.com/forum/showthread.php?t=60034

 

[Quinster]

Well completely disassembled the engine and cleaned with alcohol, decided to reassemble without RTV and just try it out, not a big job to take it apart to do if needed.

I did add lube to all o-rings and then used a friends running Aftershock as a basic guide for carb adjustments (rather than the previous owners suggestions).

I did add a new high volume fuel tank (had to go twice to the LHS as the first new one I bought on Thursday evening had a casting flaw, the output hole on the bottom did not line up with the nipple. Figured this out when I was filling the tank and there was more on my bench then in the tank).

Had a great time playing for about 2 hours this afternoon! Man compared to the RC's I used to play with (a 15 was considered a big engine back then), this thing FLYS!

The HSN was WAY too lean, and I think the whole engine was loose, it came apart too easy.

Ran great the whole time playing, started right away, re started every time I stalled it (funny how it does that when it flips 3 - 4 times and rests on its roof)

Thanks for the help, now I am hooked again, was looking at pipes and heads the other day at the LHS, and thinking about the Hpi savage three shoe clutch shoes and springs I was reading about on another thread for quicker response. Are people still running this MOD? Were there any issues?

 

[romper4444]

Get the dynamite max life light wieght shoes, they are a far better shoe, HPI's are still good, but Dynamite is also a parent company to Losi, so they are well suited for the M26. Your initial post description said to me, that your HSN was way to lean too, and would starve and want to quit when giving it full throttle. I was about to post that, but looks like you have it figured out, I don't know what everybody else was talking about being to rich, I've got the same truck and could tell right away as mine will do the same thing. The stock muffler, (it's not even a tuned pipe), really de-tunes the motor, you can go all out and get a JP-2 or 3, or a less expensive but still of excellent performance value, the Losi HT pipe. I'm running a Dynamite pipe, similar to the stock LST2 pipe, and WOW, did it wake up, it will wheelie on demand now! Any of the new Dynamite Platinum series of pipes are also excellent choices. Pretty much whatever you put on will be better than that stocker, hell I threw on my stock Savage plastic pipe, and the thing was doing wheelie's. The stock shoes are the softest shoe I've ever seen and won't last long, so upgrade before you wreck your clutch bell. Also, there really is no need to upgrade the head, it will lower your temps and fool you into thinking you can run leaner, therefore not providing enough oil to lube your engine.

 

[Quinster]

I went with the HT polished tuned pipe and header and now it is hard to keep all 4 wheels on the ground. What an improvement! Don't know why they don't just sell a better exhaust system with the truck, and charge a little more.

Thanks romper4444 for the info, will look into those shoes. The reason for looking for a replacement head is mine has some major road rash on it, and a friend of mine has one with a broken fin. So I was thinking of replacing mine, and donating my old one to him.

 

[Quinster]

Well I did love all the new found power from my truck till yesterday...anyone ever blow a tire??

This is how it looked when the truck hobbled to a stop

nice split

 

[cuz]

nice tire!! thats awesome!!

 

[olds97_lss]

I've had it happen a few times. This weekend, I added taller gearing to my aftershock after installing old school savage tires on t-maxx rims... I forgot how soft the sidewalls were on the old savage tires. Good for lower speeds in the dirt/grass, but for high speed WOT runs, my aftershock is all over the map! I'm sure a few runs with the engine/gearing I have would detonate one of the tires like yours... glad I stopped.

 

[Quinster]

kinda screwed the weekend fun...no LHS open today or tomorrow...and tires are the one thing I don't have spares of, soon to be rectified though.

 

[chuck3]

I've seen some nice crapouts in my day, but that beats them all!!

howd you manage to pull that little stunt? ill bet it was pretty spectacular!

 

[Quinster]

was doing 3 wheel donuts on some gravel, wasn't the front wheel that was expanded 2 - 3X normal size, it was actually the back wheel getting the most traction.

Lesson learned...no more donuts, well at least not at full throttle! :\