my friend asks a question

This is just a GUESS on my part. The big difference I see is that a

2cycle motorcycle engine is designed to run at med to high speeds so I'm guessing it's designed for single direction running. I'm thinking it also has reed valves and port valves and those might not work backwards.

The Oil Barge Engine, on the other hand, is surely designed to run at very low speeds, possibly as low as 200 rpm and no faster then perhaps

800 rpm. I suspect it uses valves similar to a typical car engine too. So I can imagine it might be fairly easy to design one that runs in either direction.

Its possible but the electronics won't let it and the cooling fan would not work right. Most 2 cycle engines have spark plugs and need timing of the spark. A pure diesel engine, non electronic, can run backwards.

The 2 cycle bike won't start and run backwards. The port timing in the engine along with the ignition timing won't allow it to happen.

The diesel on the other hand will run backwards easily BUT that is because it is designed that way. Very common in marine and some machinery applications.

The common method is a selectable valve train and port system. On the BIG engines they usually use either a 2 or 4 cam system with 4 valves per cylinder. One set if for forward and the other reverse. On the smaller engines such as Detroits there is a sliding valve train system and different controls to switch fuel timing and oil flow.

If the engine is built for it the operation is simple and very common in marine engines. Used with both 2 and 4 stroke diesels commonly. There are also many twin engine smaller boats that run two identical engines, except one is set up to run in reverse of the other.

On gas engines this is simple, you replace the cam with a reverse grind and the timing chain gets tossed in favor of a two gear drive. On some you also need to replace the oil pump with either a dry sump or just a remote pump.

I know that the 2-cycle Briggs and Stratton on my old lawnmower would start backwards because once I mis-assembled the pull cord assembly and managed to do it.

--scott

I didn't know Briggs & Stratton ever built any 2 cycle engines. cuhulin

what he said. [great response]

I would guess that it woudl start.

I have a motorcycle, that I fixed and ran for 5 minutes, but haven't been able to work on more.

I certainly havne't adjusted the timing. If the spark timing is like a car, set BEFORE TDC, then running it backwards would have the timing after TDC. That would make the engine a lot less powerful, But if all you neede r everse was to back into a parking place, it might still do it It wouldn't run for long and wouldn't waste that much gas.

Maybe there are other reasons a moto wouldn't run well in reverse.

The reason that it comes up is that I read about a new class of

No nothing? No adjustment for the spark timing, to make it BTDC, even though the entine is runing backwards?

I don't see in what way the valves would be running backwards even if the engine was. All they know is if the piston is going up or down.

Good to know.

But I'm amazed; you could mis-assemble the B&S pull cord backwards!! Did you put something on upsdie down, and drill a hole so it would go on!

Did the grass get longer as you ran it across the yard?