Rc runs backwards! - help

[RobertLeighty]

I'm sitting here listening to my husband (this is his wife) talk about all the problems he's been having with his RC.
He has a monster GT Truck that he has recently upgrade the motor on and he's had nothing but trouble since.... He says when he pulls the pull-start it's turning the engine backwards and when it fires up it runs in reverse.... He thinks it could be the pull-start cord wrapped the wrong way in the engine, but he can't get it to pull the other way at all either..... if anyone knows what might be causing our problem, please help.....:\

 

[charliejp]

If you're looking at the front of the motor, does it turn clockwise or counter clockwise?

 

[Rolex]

Howdie, Ma'am, and welcome to RCNT.
It's unlikely that the engine is running in reverse.
If it's a truck with both forward and reverse gears in it, it either needs to be shifted into forward, or the servo switch needs to be reversed to shift in the proper direction.
The other possibility is a differential being backwards or upside down.
I'll move this thread to the General Nitro section where it will get more attention.
Tell him to stay calm. We'll get him up and running. It's what we do best.

 

[olds97_lss]

If the starter cord was wound the wrong way, then the clutch inside that catches would also have to be backwards. Both of which are fairly unlikely, but aren't impossible.

Usually the hole that the cord goes into is off to one side of the housing and goes straight down to flow easier with the spool and housing so it doesn't rub on the housing. Is his cord going straight down or at an angle?

You can kind of see what I'm talking about by looking at these two engines:

If the cord was wound the wrong way, the handle would want to point to the side instead of straight up.

Oh, welcome to the site and good luck!

 

[RC Addict]

Sounds like a classic case of upside down diffs. If he stripped the chassis to change mills then it is VERY easy to do, if it is not a shifted into reverse issue as Ralph pointed out.

 

[RobertLeighty]

If you're looking at the front of the motor, does it turn clockwise or counter clockwise?

Its turnig counter clockwise. It will start sometimes in reverse and forward. Right now i can't figure out why. i havn't touched anything on the diffs or trans

 

[Rolex]

If you know it's actually running in both directions, then this would be my theory from my experience with airplane engines. When props are spun with a finger to start the engine, they will often reach the compression, then spring in the opposite direction, starting the engine in reverse.
You could be getting the same affect by pulling the cord too slowly. You need to give it short, rapid pulls to give the flywheel enough rotational inertia to continue in the right direction.

 

[olds97_lss]

The only time I've had that happen with a pullstart equipped engine is when the starter clutch bearing (OWB) was getting really worn and wasn't grabbing very well to begin with.

With a new bearing, I'd be surprised if it could run in reverse on you. I would think the bearing would stall it. Or break your rope... but more than likely stall.

 

[RC Addict]

Doubtful the OWB is that worn out as Bryan stated. I am going with Ralph's original assessment: check your servo and transmitter. It sounds like you are in reverse (though that does not explain the engine firing up backward). If the OWB was that bad it probably wouldn't even start at all. Fire the mill and run the rig (should go backward, right?). If you can hit second gear then we gotta do some head scratching. If it stays in low you are most likely in reverse. That is all my brain can come up with...

Its turnig counter clockwise. It will start sometimes in reverse and forward. Right now i can't figure out why. i havn't touched anything on the diffs or trans

By that do you mean that sometimes you start it and the truck works fine (goes forward) and sometimes it goes backward (in reverse), or are you talking the direction the flywheel turns??? If the flywheel ALWAYS turns counter clockwise then there is but one answer: You are sometimes hitting reverse on the transmitter before you start the rig. Get a Forward Only Conversion kit or keep your finger off the switch.

 

[Rolex]

Keep answering our questions, Robert, and we'll soon come up with the solution.

 

[militarymaxx]

I had often heard stories of nitro engines running backwards and then one day I started mine, set it down and throttled up and yup, backwards. I remember when I started it, it was a real quick burp on the starter box and it fired right up. Weird but it was running backwards and I could never re-produce it again.

 

[x_doug_x]

any 2 stroke engine will run in either forward or reverse, which ever way it is turned. in your case on a starter box, just place the car backwards on the starter box, it will start in reverse. i had a goped when i was 10 years old or so and pulled in my yard "the scooters with gas motors you stood up on" and i pulled the front breaks and leaned forward messing around, i endo'd it and it came back down on the tire and rolled backwards and started in reverse. this was the moment i realised that.

the problem with starting a pull star motor in reverse is it's almost impossible via the one way bearing will grab and stall it or at least it should or it will rip the rope, break the spring, something. the one way bearing catches and spins the pull start the wrong way, in this case most of the time they will not start... it does sound like this guy has a bad one way bearing, if he didnt it should real the pull cord in and stall it.

 

[Scrogg]

I have seen an engine run backwards once or twice, never a pullstart engine.
To make starting easier, preheat the engine with a heat gun or hair dryer for 4 or 5 minutes. Start it up, it should fire up much easier and run properly. If not, let us know.
Some pics will help, along with a detailed description of everything you did to install the engine.
Remember to put the piston at BDC when you are done running it.