Running China Motor backwards ?? Successfully ??

[ToyTruck]

Has anyone Successfully run a 2 stroke motor backwards ??
Any issues apart from adjusting the timing ?

Anyone have ideas for re-timing ?? Offset key way obviously won't work . Is it possible to re cut a new keyway

 

[Racie35]

might be easier to cut a new slot in the flywheel....you couldnt file a keyway enough to move that far.....or maybe move the ignition magnet or pickup?

 

[crassius]

saw one that ran backwards on the work stand once - seemed to run well that way, but I didn't stay around long enough to see what they found was wrong with it (it was intended to run normally)

 

[ToyTruck]

Thanks for the info ....
The motor will be rack mounted on a DownHill MTB
No room for jack shaft and I want to keep my rear disc
So the plan is to run the sprocket in behind the freewheel cassette

The sprocket fits so now I need to figure out the timing mods

 

[BigBlue]

I assume China engine means a pocket bike or Cage engine and not the China Girl or Happy Time. You could probably run a RC ignition system with a hall sensor as a pickup.

You might want to look into the Tophat system from Kings that allows your to have a sprocket and disc to be mounted on the same mount: http://kingssalesandservice.com/

Another thing, how do you plan on starting the engine?

Good Luck,

Chris
AKA: BigBlue

 

[ToyTruck]

Sorry , I meant the Happy Time engine .... Waiting for a kit to arrive

 

[keatonx]

i have made weed eater generators and would put power through the generator motor to start it. one time i hooked up the wires backwards and it tried to start, but backfired real hard out both ends of the engine (carb and muffler). My friend and i made a friction drive weed eater bike and we bump started it backwards. it did the exact same thing. Different engine, but you will likely have the same problem. it will run fine if you fix the timing, but may not last too long. the piston rubs mostly on one side of the bore due to the crank position during the power stroke. Its hard to explain, but it wedges into that one wall because the con rod isnt straight at TDC when the explosion occurs. Therefore the engine is designed to get alot of lube and cooling in that area. reverse the rotation and the piston wedges against the other wall, which will have less lubrication and cooling than the other, original side. i dont know how substantial this is, but it will likely happen to some extent.

 

[ToyTruck]

Different engine, but you will likely have the same problem. it will run fine if you fix the timing, but may not last too long. the piston rubs mostly on one side of the bore due to the crank position during the power stroke. Its hard to explain, but it wedges into that one wall because the con rod isnt straight at TDC when the explosion occurs. Therefore the engine is designed to get alot of lube and cooling in that area. reverse the rotation and the piston wedges against the other wall, which will have less lubrication and cooling than the other, original side. i dont know how substantial this is, but it will likely happen to some extent.

Thanks , that's something I will keep an eye on ....
I have already fitted the motor , and am just trying to set the timing now.

Any other suggestions as to where to set the timing at ???

 

[Old Bob]

Mirror image of what is was before.

If you don't know, then set it about 25 deg, BTDC.

And don't worry about wrist pin offset.

 

[ToyTruck]

Thanks , I got it running and it seems good enough.

Although it does stumble a bit at high rpms ...
I am thinking it may be fuel issues as my tank is probably not high enough to give a good gravity feed.
The filter is about 2 inches away from the carby and seems to always have fuel?


Could the timing affect the rpms as much as I am seeing ?
It does seem to rev right up on a good downhill!