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BEC reverse
JeffHs - 1/12/08 at 03:32 PM

This is how to do it!

Power was provided by the newly introduced 197cc Villiers Mk9E engine with a better clutch, smoother gear changing and from 1957 a four-speed gearbox in place of the old three-speed one. The De-Luxe
model featured improved electrics using a SIBA Dynastart unit - which was available with a reversing option. The later allowed the engine to be started in either direction - effectively giving such equipped Minicars an effective reverse gear - ALL the gears in reverse in fact, a feature which was no doubt tried out by one or two "adventurous" owners?

Mr Whippy - 1/12/08 at 03:35 PM

that is if you want a smokey 2-stroke in a pink and frilly BEC

real mens engines only go one way



[Edited on 1/12/08 by Mr Whippy]

stuart_g - 1/12/08 at 03:39 PM

quote:
Originally posted by Mr Whippy


real mens engines only go one way



Yeah down to the bottom of the sea

Edit to add a four stroke model aircraft engine I had many moons ago would sometimes run backwards if it back fired while trying to start it. It would most of the time back fire and then run the correct way when the throttle was slightly opened, so it is possible for some four stroke engines to run backwards.



[Edited on 1/12/08 by stuart_g]

smart51 - 1/12/08 at 03:41 PM

2 stroke engines will run in either direction. 4 strokes won't.

PS. Mr Whippy really is trying to compensate for something isn't he?

Richard Quinn - 1/12/08 at 03:49 PM

quote:
Originally posted by Mr Whippy
that is if you want a smokey 2-stroke in a pink and frilly BEC

real mens engines only go one way



[Edited on 1/12/08 by Mr Whippy]
2 stroke is a real man's engine. Look at the power outputs from the old GP bikes. Proper tuning with templates of porting being made using a similar process to brass rubbing, a die grinder and Dremel.

02GF74 - 1/12/08 at 03:50 PM

quote:
Originally posted by smart51
2 stroke engines will run in either direction. 4 strokes won't.

hmmm, not sure so about that. when I was wee lad, I overhead conversation in library (for those not familiar, it was a big place full of books, books being things that you read) where some geezer said that it was possible to get a single cylinder bsa or norton to run backwards if you kick started it and it back fired. If this happened, you could make the mistake of dropping in the clutch and find yourself going backwards instead of forwards!

I have wondered many years about this and posted the question on a bike forum and the consesus was it was posible but if would run inefficiently.

so I think they can run backwards; ofcourse with an electric starter, you won't have the same conditions to get it to do that.

BenB - 1/12/08 at 03:50 PM

quote:
Originally posted by stuart_g
quote:
Originally posted by Mr Whippy


real mens engines only go one way



Yeah down to the bottom of the sea



dinosaurjuice - 1/12/08 at 04:12 PM

i dont think the oil pump on a four stroke will be very effective running backwards....

Mr Whippy - 1/12/08 at 04:59 PM

model 4-strokes don't run backwards. its the 2-strokes that do that and even then have little power, I have many of them both

stuart_g - 1/12/08 at 05:29 PM

quote:
Originally posted by Mr Whippy
model 4-strokes don't run backwards. its the 2-strokes that do that and even then have little power, I have many of them both


Oh yes they do I have had them do it lots of times, yours must have been "real mens" ones if they didn't

[Edited on 1/12/08 by stuart_g]

afj - 1/12/08 at 06:04 PM

stuarts right ive had some 4 stroke model engines run backwards

smart51 - 1/12/08 at 06:27 PM

quote:
Originally posted by 02GF74
quote:
Originally posted by smart51
2 stroke engines will run in either direction. 4 strokes won't.

hmmm, not sure so about that. when I was wee lad, I overhead conversation in library (for those not familiar, it was a big place full of books, books being things that you read) where some geezer said that it was possible to get a single cylinder bsa or norton to run backwards if you kick started it and it back fired. If this happened, you could make the mistake of dropping in the clutch and find yourself going backwards instead of forwards!

I have wondered many years about this and posted the question on a bike forum and the consesus was it was posible but if would run inefficiently.

so I think they can run backwards; ofcourse with an electric starter, you won't have the same conditions to get it to do that.


On a 4 stroke it is the cam timing that stops it running backwards. Running forwards, the inlet valves are open when the piston is going down, followed by compression, spark and the power stroke. The exhaust valves open and the piston moves up. In reverse, the exhaust valves would open and the piston move down. There would be compression then the spark during the "power" stroke. Finally the inlet valves would open blowing air through the carbs or past the fuel injectors. It wouldn't run.

lococost - 1/12/08 at 07:07 PM

so, just put some injectors in the exhaust system and we have instant BEC reverse!

Dingz - 1/12/08 at 07:39 PM

A looong time ago my first scooter had a villiers 197 (9e) with dynastart, basically the dynamo on the crank is used in reverse as a starter motor. It wasn't supposed to but did once start the motor in reverse, it was quite a suprise to me when I tried to pull away, especially as it was a hill start

Mr Whippy - 2/12/08 at 07:25 AM

quote:
Originally posted by smart51

On a 4 stroke it is the cam timing that stops it running backwards. Running forwards, the inlet valves are open when the piston is going down, followed by compression, spark and the power stroke. The exhaust valves open and the piston moves up. In reverse, the exhaust valves would open and the piston move down. There would be compression then the spark during the "power" stroke. Finally the inlet valves would open blowing air through the carbs or past the fuel injectors. It wouldn't run.



Exactly correct, 4-strokes do not run backwards without another camshaft

2-strokes do as despite the inlet timing being out they do have sufficient inlet/outlet overlap to allow the gas to exchange and the engine to run on reduced power


[Edited on 2/12/08 by Mr Whippy]

Triton - 2/12/08 at 05:16 PM

You can't beat a mad stroker especially with loud spannies........

adithorp - 2/12/08 at 07:27 PM

I used to have a 2 stroke outboard that would run backward and forward at the same time. It would fire just before TDC and turn the other way and then repeat so the crank did less than a turn in each direction. It sounded right when it did it but you just couldn't go anywhere as the prop just went back and forward as well.

adrian

designer - 2/12/08 at 08:19 PM

Don't forget that the EU are going to ban 2-strokes. They have started with the outboard, bikes are next.

sickbag - 4/12/08 at 11:56 AM

I've got 4 2-smokes in my garage - and neither of them runs at the moment (

Can't wait until they've been finished though - a smoke screen the A-team would be proud of.

For those that love 'em (and interested) I've got:

Nearly restored Kawasaki KH125 (cheap commuter)
Nearly restored Yamaha RD350-YPVS )
Waiting to start rebuild Suzuki GT380 triple
and finally
An original condition Honda NS250R (race bike with lights, not to be confused with the later road going NSR250)

motorcycle_mayhem - 5/12/08 at 04:20 PM

Attempts to run the Suzuki GSXR750 backwards in the car (i.e not hitting the clutch pedal quick enough on a spin) have met with no success. It won't.
What it does though is engage the starter clutch and whips the poor starter over at several thousand RPM! The inside of the starter motor then resembles coal dust, everything explodes.

motorcycle_mayhem - 5/12/08 at 04:23 PM

While I'm here, I can dream of an RG500 powered 7. The other guy here got me all sentimental when he mentioned an LC.
Nearly killed myself on a 250LC back in 1980, one of the RTA statistics that no doubt contributed to the 125cc learner limit.