Dual Engines

[NS125RK]

How would you go about using multiple engines in a bike? I understand the general concepts of how engines work and am quite mechanically minded although I have no actual experience to back it up. But I am finding it hard to find any information on this.

Theres no need to go into exact information about it but just a general overview should be enough.

[R4nger]

I am thinking out loud here so...

Get a custom frame since two engines won't find in one frame. It would be alot easier to get 2 of the same engine so the ratios are the same and then make two of everything (carbs, cables, fuel hoses) and then link up the find drive or have two rear spockets.

[NS125RK]

yeah I wasn't really thinking of adding an engine to an existing bike but to basically start from scrath. Just really need to know what to base my ideas around.

For abit more information I was thinking about a 1ltr 2 stroke. Thought it would be nice to play with.

[Barry_M2]

Wont work, or rather would be very hard to get them to work together.

The best you can do it get two identical blocks and get a one off custom crank made with the cases welded together. I think a someone like Caterham or simelar have put together 2 1000cc bike engines in V config to make a 2 litre V8. I'll try and find the info and post it up...

[Ric]

what u cant work out is on catterams how do both engines power the drive shaft?

and puttin two drives on a bike will just make it torquey?

[Barry_M2]

The twin engine Caterhams are 4wd. One engine powers the front, other the rear.

I mean they made 1 V8 engine by welding 2 1000cc 4 cyl engines together. So it still only had 1 crank and 1 gearbox to drive.

The problems you'll have if using two completely seperate engines to power a vehicle will be 'alot', even more so for them to drive the same wheel!!! Power and torque will need to be exactly the same, you then have the trouble of getting them to rev identically and produce the same power at the same revs at the same time, and then for both of them to change gear at the same time, try making something mechanical to do that!!!!!! You'll need a quick shifter on both engines. Then there is finding space in the frame in the first place.

You would only want 1 crank.

Would also be easier to use a 2 stroke as there are alot less moving parts.

[cagiva gezzer]

https://www.macdizzy.com/images/bbs/849.jpg

1000cc Stroker?
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"because one stroke isnt enough and four strokes waste two"

[G]

Tiger have used a 'torque combining shaft' of some kind to get both engines powering the rear wheel.

The more important question in a bike is 'why'?
On a car it means you can use a light bike engine to get a stupid amount of power fairly cheaply without the massive weight of cheap and powerful big car engines.

Having two completely seperate engines on a bike I can't see offering much.

[stinkwheel]

I have seen a picture of a drag bike that used four 500cc methanol snorting speedway engines conected in series by a chain at the primary drive.

There was a dog clutch between each motor so you kick started the first one then engaged the clutch onto the second one which bump starts, then the third, then the fourth.

Then try to hold on.

https://www.werner-broesel.de/rpkstbord.jpg
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[G]

I seem to recall an article in MCN many years ago about a bike with 3 big V8s (forget which, but some aermican one).

Doubt it could go very fast and I reckon it's wheel base was longer than my van. Got a feeling it could seat 4 or something though!

[ZRX61]

[wantser]

the only twin engine machine that I have seen work really well was a Zcars twin R1 mini. See attached. So it must be possible, but with a custom frame and drive system. I personally have never heard of any other successful twin motorcycle engined machines.

This mini was blistering tho! Maybe you could adapt the same theory and setup on three wheels? It would save hassel...a lot of it!
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An expert is a person who has made all the mistakes that can be made in a very narrow field

[ZRX61]

[wantser]

[MarJay]

A more promising concept IMO is to take the top ends from two engines and then a bottom end on which to mount the two top ends.

So as an example, take the block, cylinder heads, cams etc from a Hayabusa, and mount them on a suitable vee configuration bottom end with crank etc.

This has been done, for use in small kit cars afaik.

The result would be instead of a 1300cc inline four, you would end up with a 2600cc V8, with only a slightly greater total volume and weight.

2600cc V8 bike?

Japanese rev ceiling?

Yes please!
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British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F; Cheap project: CBR900RR FireBlade
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[G]

Also, I believe it's illegal to have two seperate engines on UK roads, for your information.

In a car I've always wondered if you do need those fancy torque couplers or if you could have both engines connected to an axle by a sprocket engine; as engines are used to being run under different loads for the same throttle position; for instance going up/down hill etc.

[mchaggis]

I wonder if you could connect more than one engine to the same shaft with sprag clutches?
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I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[DukeRed]

My friend had a go cart with two 4stroke honda engines powering the back wheel by having two sprockets. Had one engine by each elbow.
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Enjoy Life There's Plenty of Time to be Dead
https://www.janoner.com

[ZRX61]

[mchaggis]

https://www.the-antar.co.uk/032.jpg

You really wouldn't mess with one of those...
____________________
I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[stinkwheel]

Just thinking out loud, but could you do something with the diff box from a car? Use it backwards so the engines are on the half shafts and the drive shaft goes to a sprocket or shaft drive?

Or would one engine just rev its nuts off and the other stall out?

I'm not really a car person
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[no_shad]

Can't help but be impressed by this:

https://www.tigerracing.com/cars/tiger-z100-main.php
https://www.tigerracing.com/graphics/tiger-z100-mk2.jpg

[wantser]