Author Topic: Reversing an engine  (Read 2284 times)

Online chrisk

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The initial attraction to motorcycling inflicts people for various reasons and at different stages in their lives. But once someone experiences the elation of riding a motorcycle there’s no denying the nearly spiritual effect it has.

Offline markQLD

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Re: Reversing an engine
« Reply #46 on: May 16, 2018, 09:03 »
Something like this? http://www.ashonbikes.com/sites/default/files/images/BMW_F800_balance_2.jpg
a left-side clutch?     (thumbup)
a right-side output?  (thumbup)
a 6-speed box?        (thumbup)

Give that man a beer  :D

Online chrisk

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Re: Reversing an engine
« Reply #47 on: May 16, 2018, 09:27 »
Ok, you owe me at Morgan Park.
The initial attraction to motorcycling inflicts people for various reasons and at different stages in their lives. But once someone experiences the elation of riding a motorcycle there’s no denying the nearly spiritual effect it has.

Offline CLEMTOG

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Re: Reversing an engine
« Reply #48 on: May 16, 2018, 09:37 »
and 87BHP at 8,000rpm plus 63 ft/lb torque at 6,000rpm,

that is why I want to install one of these BMW/Rotax units in a 668 chassis, it does fit and even the gearbox sprocket has the correct amount of teeth for blistering performance, The F800R figures are the ones I quote
compare this to the standard Lav motor (claimed !! ??) of 65BHP at 7,800 and max torque at only 600 revs slower (?????) of 44ft/lb at 7,200rppm.

ditch the reversed motor project Red and build as above, I am told that North of 100BHP is available if you look for it, and just think of the weight.!
CLEM

Offline Brett

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Re: Reversing an engine
« Reply #49 on: May 16, 2018, 10:54 »
What I will be looking forward to is Smarty mastering the rear wheel steering  (bolt)

that said I'm off for a kip see ya in Morgan Park  8)
Sitting on the fence 120 or 180 that is the question ?

Offline Davo

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Re: Reversing an engine
« Reply #50 on: May 16, 2018, 11:01 »
Bevel drive connecting the crank and clutch, ooooh errrrr.  >:D  :laugh:
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Offline MotoJouni

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Re: Reversing an engine
« Reply #51 on: May 16, 2018, 15:00 »
Reversing starter motor free clutch, if starter motor is used.

I have thought earlier that many four pole starter motors can be probably easily reversed
just by turning the center sleeve (the part that has four permanent magnets inside) by 90 degrees. It swaps
the north and south poles of the permanent magnet section. No need to switch the polarity and therefore no need to isolate.
Reversing at any method if brushes are not at centerline of the axle can create problems to the brushes.

Reversing engine rotation (with standard cams) swaps the firing order from 132 to 123. I don't know does it have
any effect that should be taken in account to crankshaft vibrations.

One possibility: Reverse rotating engine with chain primary (tensioner on the top of the primary cover) and reversing type gearbox.


If the only thing to be solved is the gear box durability (not like 6 speed gearbox, different handling with reverse rotating crankshaft),
it would be interesting to hear which parts actually fail from the gearboxes. I mean sounds possibly lubrication problem to me,
not actually knowing what is the situation there. And what else on gearbox section is to be solved with this reversing than that would
not be solved with that extra bearing on the sprocket cover you made earlier? To eliminate the bearing in where two shafts are on inside another?

Direct drive gearboxes are also used on some drag racing vehicles so it should not be weak in principle, of course the design itself is a different thing.
Many of those V8 gearboxes have parts of similar size than Breganzie twin/triple gearboxes have.

Needle bearing solution should have multiple times load carrying capacity than bronze bush solution of similar size (when there
is enough oil film strength; needle bearing solution also needs more of this because of smaller contact area).
Here in Finland many lubrication problems from vehicles followed by very high surface pressures (leads to metal to metal contact)
and/or too less feed of oil (by design flaw for example) were many times easily solved with suitable extremely high film strength oils,
and sometimes increasing the oil feeding to bearings/sliding surfaces.





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Online chrisk

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Re: Reversing an engine
« Reply #52 on: May 16, 2018, 21:16 »
and 87BHP at 8,000rpm plus 63 ft/lb torque at 6,000rpm,

that is why I want to install one of these BMW/Rotax units in a 668 chassis, it does fit and even the gearbox sprocket has the correct amount of teeth for blistering performance, The F800R figures are the ones I quote
compare this to the standard Lav motor (claimed !! ??) of 65BHP at 7,800 and max torque at only 600 revs slower (?????) of 44ft/lb at 7,200rppm.

ditch the reversed motor project Red and build as above, I am told that North of 100BHP is available if you look for it, and just think of the weight.!
CLEM

I wasn’t aware they were a Rotax engine ...... cor, maybe I just found the perfect motor for my spine frame?
The initial attraction to motorcycling inflicts people for various reasons and at different stages in their lives. But once someone experiences the elation of riding a motorcycle there’s no denying the nearly spiritual effect it has.

Offline redax5

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Re: Reversing an engine
« Reply #53 on: May 16, 2018, 22:46 »
was just reading a road test on the new Speedmaster from Triumph and it is right hand chain drive 6 speed box

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Offline redax5

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Re: Reversing an engine
« Reply #54 on: May 16, 2018, 22:54 »
Reversing starter motor free clutch, if starter motor is used.

I have thought earlier that many four pole starter motors can be probably easily reversed
just by turning the center sleeve (the part that has four permanent magnets inside) by 90 degrees. It swaps
the north and south poles of the permanent magnet section. No need to switch the polarity and therefore no need to isolate.
Reversing at any method if brushes are not at centerline of the axle can create problems to the brushes.

Reversing engine rotation (with standard cams) swaps the firing order from 132 to 123. I don't know does it have
any effect that should be taken in account to crankshaft vibrations.

One possibility: Reverse rotating engine with chain primary (tensioner on the top of the primary cover) and reversing type gearbox.


If the only thing to be solved is the gear box durability (not like 6 speed gearbox, different handling with reverse rotating crankshaft),
it would be interesting to hear which parts actually fail from the gearboxes. I mean sounds possibly lubrication problem to me,
not actually knowing what is the situation there. And what else on gearbox section is to be solved with this reversing than that would
not be solved with that extra bearing on the sprocket cover you made earlier? To eliminate the bearing in where two shafts are on inside another?

Direct drive gearboxes are also used on some drag racing vehicles so it should not be weak in principle, of course the design itself is a different thing.
Many of those V8 gearboxes have parts of similar size than Breganzie twin/triple gearboxes have.

Needle bearing solution should have multiple times load carrying capacity than bronze bush solution of similar size (when there
is enough oil film strength; needle bearing solution also needs more of this because of smaller contact area).
Here in Finland many lubrication problems from vehicles followed by very high surface pressures (leads to metal to metal contact)
and/or too less feed of oil (by design flaw for example) were many times easily solved with suitable extremely high film strength oils,
and sometimes increasing the oil feeding to bearings/sliding surfaces.

we don't use a starter motor on the race engines so no issue there.
in fact we had to reverse the direction of rotation on the Pingel remote starter we purchased to suit the right hand engine side connection so would suit us to go back to a normal Pingel starter

main aim is to get rid of the sleeve gear on 5th and gain an extra gear
current failure is always breaking the mainshaft where it enters into the sleeve gear due to bending moments caused by running 17" slicks thus increased load and too much power
we will know if our outboard bearing set up works by Sunday night as racing this weekend

we machine our race cranks and the final design is symmetrical so crankshaft balance and vibration should remain the same
I think

you are right in saying lubrication to the gearbox is an issue and is something we are looking at next time engines are open, been a bit rushed this time just getting this latest modification completed in time to make it to this race meeting

thanks all for some neat ideas, lots to talk about this weekend



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near Brisbane, Australia

Offline Davo

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Re: Reversing an engine
« Reply #55 on: May 17, 2018, 02:32 »
was just reading a road test on the new Speedmaster from Triumph and it is right hand chain drive 6 speed box

Mind you, it's only pumping 76Hp through those gears.
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Offline Dellortoman

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Re: Reversing an engine
« Reply #56 on: May 17, 2018, 02:39 »
Bevel drive connecting the crank and clutch, ooooh errrrr.  >:D  :laugh:

You beat me to it Davo. I came up with the same idea last night. It's not as silly as it sounds. Put bevel gears on crank and clutch, then mount a short idler shaft with a bevel pinion each end to transfer the drive between them. A bit like two diff crown wheels with a short shaft between them.

The advantage of such a design is that the idler shaft and its bearings would be housed in a re-designed primary case, so there would be no need to modify the crankcases to carry idler bearings. In addition, it reverses direction with a single idler shaft, so only 2 pairs of meshing gears. Further, spiral bevel gears have slightly higher efficiency than spur gears, so the whole drive may end up having similar efficiency to a nice new chain drive, but chain stretch is eliminated so it will hold its efficiency longer than a chain.

It'll mean an odd shaped primary cover with bulges where the gears and bearings are, but it's not in an area that will get in the way of anything.
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Offline Piranha Brother 2

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Re: Reversing an engine
« Reply #57 on: May 17, 2018, 09:01 »
was just reading a road test on the new Speedmaster from Triumph and it is right hand chain drive 6 speed box
You beat me to it, Red. Was getting tyres swapped at a custom moto place in m suburb and they had a project bike based on a Triumph twin of some sort - and yep, noticed it had RH chain. Thruxton 900s were 5 speed, 1200s are 6.

I noticed because I'm using a Triumph 900 twin (TT legend?) rear hub and had observed that the cush drive rubbers were not symmetrical, seeming to have more cushioning rubber on the drive side if it was a LH chain. And indeed they are LH chain, so no idea why they went to RH on the later models. Obviously a completely new motor design.
What ... leave it standard??!!

Offline Davo

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Re: Reversing an engine
« Reply #58 on: May 17, 2018, 13:23 »
You beat me to it Davo. I came up with the same idea last night. It's not as silly as it sounds. Put bevel gears on crank and clutch, then mount a short idler shaft with a bevel pinion each end to transfer the drive between them. A bit like two diff crown wheels with a short shaft between them.

The advantage of such a design is that the idler shaft and its bearings would be housed in a re-designed primary case, so there would be no need to modify the crankcases to carry idler bearings. In addition, it reverses direction with a single idler shaft, so only 2 pairs of meshing gears. Further, spiral bevel gears have slightly higher efficiency than spur gears, so the whole drive may end up having similar efficiency to a nice new chain drive, but chain stretch is eliminated so it will hold its efficiency longer than a chain.

It'll mean an odd shaped primary cover with bulges where the gears and bearings are, but it's not in an area that will get in the way of anything.

Thanks.

I thought it was quite a clever solution myself.  ;D
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Offline wdietz186

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Re: Reversing an engine
« Reply #59 on: May 17, 2018, 20:56 »
Why not adapt the Laverda top end to a SpeedTriple bottom end, or maybe the old Yamaha XS 750? Might be less work than making cases/primary drive etc.