[RC_Newb]

Hey Everyone, I'm new here. I'm hoping somebody here could help me troubleshoot the problem I'm having. I have a Losi Aftershock that a friend of mine rebuilt for me a couple years back. It's been sitting in my garage for a couple years. I decided to get the thing going again. Last time I used it, I used the after-run oil and whatnot and drained the fuel so it was stored properly. I fueled it up and tried using the rotostart to fire it up, but the thing just spun and it didn't sound like anything was catching. I figured my rotostart mechanism was buggered so I went and bought a new pull-start mechanism and put it on there instead. But the same thing happened, I would pull the cord and it just came out freely, like it was not catching. Once every 5 or 6 pulls it will catch and give some compression but not enough to start the thing.

The truck is practically new and it ran fine last time we ran it, so I'm not sure what could have happened. I haven't dealt with these nitro motors before so I don't have a clue what the problem is. Would really appreciate any help you guys can give me.

[Cougar429]

You don't mention if you actually see the motor shaft turning, (don't know that one. I'm an airplane and heli guy).

However, you can test it yourself by pulling the glow plug and feeling if there is a compression pulse as you yank the starter. If not then the system is not engaging the motor shaft.

There are requirements to get any motor to light off. In our case you need good fuel, (if it has sat around for any length of time it may grow stale and not work at all) physical compression as the piston climbs up the cylinder, and a source of heat for ignition. That's where the glow plug comes in. The platinum wire requires initial current to warm up and start the motor. From there a catalytic reaction with the fuel continues to keep the wire hot enough for the next ignition, even when you remove the electric supply.

That ignition also needs the correct mixture, as too rich or lean interferes with the following ignition cycle and the motor can stop. Ther is also the case for compression. This means a nice tight fit betwen the piston and cylinder, no loose, broken or seized ring, leaking head or glow plug gaskets, etc. As i said, I don't know your motor, but a ring style motor can tolerate a slightly wider mixture range. ABC motors use the heat of combustion to change the dimensions of the parts so they then take on the proper clearances. If you run them too lean they can heat up and start to bind and score.

Finally, the fuel mix itself is important. The proper amount of nitro can make a motor perform to the max, (this should be listed in the motor or vehicle specs. If not, see if any others run that rig and pick their brains. In some cases they may know some tricks that are not published). Same can be said for the lubricant. A lot of the stuff at our LHS is full synthetic, but I have always liked castor and try to stick with it.

[RC_Newb]

I'm fairly sure the motor shaft isn't turning. It catches once every several pulls and turns the shaft and gives good compression, but something somewhere must be loose. Just don't know where to look, and what to look for.

Thanks for all the other info tho.

[jake_027]

It sounds like you one way bearing is slipping. Take it out and clean it with alcohol or brake cleaner and then reinstall. You should be good to go!

[Cougar429]

Is there any way to remove the pull start and check that the part it engages is not loose, broken keyway or pint, etc? The fact you had two separate start systems react the same way tells me that the problem lies a bit deeper.

Hey, did I mention we always like pics? Sometimes they can tell a thousand words. Just be sure to use macro if your camera has it and good lighting.

[RC_Newb]

Here are a few pics of my truck Can't wait to get home from work so I can try the stuff you guys mentioned above.

[misfit]

+1 for the one way bearing... i'd bet my bottom dollar on it, engine is going to have to come out to get that pull start case off though... and if i recall the transmission is going to have to be loosened off(been a while sice i had mine).......
beautiful aftershock though... did you put in the lst2 2-speed in it yet? night and day difference in power delivery when i did it to mine....

[RC_Newb]

I bought the LST2 2-speed Ti-Ni gear set for it. But I'm to scared to pull all that mechanism apart cause I don't think I'm bright enough to get it back together. LoL I'm tryin to find somebody in town here to come over and help me with it.