# Any plans for a v-twin small engine around?



## AlfJones (Dec 22, 2011)

Hello all.

My grand plan of getting new toys ( new, much bigger mill and lathe ) and then launching straight into a loco build, and a rarely built loco at that, is, I think, perhaps a little TOO challenging a way to get to know my new toys.

I want something a bit taxing, but where I loose only a few hours/days work with when I make the inevitable mistake, rather than weeks worth of work on something vastly larger.

Something that I would quite like to build, because I actually have a use for it, is a fair sized 2-stroke engine - something like a 0.60 or a 0.74 ( about 10 - 12 cc ) size. I've always liked the idea of a v-twin, but now I come to think of it, I don't think I've ever seen any plans for one.

So, I was wondering if anyone here has ever come accross any v-twin 2-stoke plans that are either in the right sort of size range or that I can scale up/down. Even better, plans and a build book, or a series in a magazine would be even better. I know there are a lot of straight-2's about, and they would do the job, but they're just not as nice to look at I think?

I think that might be a good challenge, but it's much smaller than a 5" loco. Not only that, it's small enough that I can throw it accross the room much easier if I make a serious mistake.


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## b.lindsey (Dec 22, 2011)

You might check out Jerry Howell's v-twin at www.jerry-howell.com. Its not 2 stroke but could make a nice project. Jerry always did a nice job on his plans.

Bill

EDIT: And being a bar stock project, if you mess something up, you don't have to worry about replacement castings!!


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## Jasonb (Dec 22, 2011)

Just above your size range at .90 is the Chenery Aero Twin, though its a 4-stroke

http://www.hemingwaykits.com/acatalog/Aero_Twin.html

Or a nice barstock twin 4-stroke is the Hoglet that was covered in MEB mag, a search here wil throw up several builds.

J


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## GailInNM (Dec 22, 2011)

I have not seen any 2-stroke V twin plans. 

A two stroke V Twin would be a difficult design. On a simple single cylinder two stroke the fuel/air mixture is transferred to the cylinder by compressing it the crank case and then passing it through the intake port on the cylinder as the piston approaches bottom dead center. This will not work with a V twin as the primary compression (crankcase) will be low as the pistons are not in phase and even then the first cylinder to open the transfer intake port would hog all the fuel air mixture. The only way to make it work with out adding an external pressure source, blower or other pump, is to isolate the crankcase halves for the two cylinders which leads to seal problems and separation between the two cylinders which looks funny and makes for a long engine.

When everything is considered, a four stroke V twin is more practical. 

Simple two cylinder two stroke engines that are practical to build are simultaneous firing such as an opposed twin with the cranks offset by 180 degrees, known as a boxer, or two cylinder in-line twins with the cylinders firing at the same time with the piston rods on a long common crank pin with bearings at each end so it acts like two single overhung crankshafts. Slightly more complicated are alternate firing vertical twins with the crankcase separated tin to two halves by a center bearing.

Gail in NM


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## AlfJones (Dec 23, 2011)

There are a whole family tree of 2-stroke designs that can be played with. v-twins and v-quads have been built at 1:1 sizes, and there are also other lovely designs such as split twins as well, that have also been laid out as "almost V's" - I think some of the old Excalibur's did this.

I think your right though - a v-twin 4-stroke will probably fit the bill a lot better - it's meant to be a training excersise after all.

The Chenery is a lovely looking engine - I've sent off for the plans to see how it looks to build.

Thank you gentlemen for your idea's.


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## gbritnell (Dec 23, 2011)

A v-twin 2 stroke could be made. Before the demise of the 2 stroke street motorcycles there were many twins and triples out there. What you would have to do is offset the cylinders enough to separate the crankcases internally as a 2 stroke gets it's feed through the crankcase for lubricating purposes. 
If you go with a 4 stroke V-twin I have drawings for the one I made. It has a bore and stroke of 1.00x1.25 inches. It's overhead valve with and open valve train. It has pressure oiling to the rods and cams. 
gbritnell


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## Admiral_dk (Dec 23, 2011)

Hi

There's a wonderful V-Twin Diesel on http://modelenginenews.org/ at Model Engine Gallery Page 8, 3 pictures down + a drawing og this 1cc twin. You could upscale the size to your requirements - remember that a 5cc diesel is just as powerful as a 10-12cc glowplug engine.


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## Niels Abildgaard (Dec 24, 2011)

A V2 90 degree two stroke (Fourstrokes are mechanical misconceptions) is about the smoothest running thing imaginable.The combined pumping volume of the two pistons corespond to one normal single piston but modern two stroke can run without crankcase pumping when on pipe.This means the exhaust pipes are doing the charge and scavenge work when working hard.


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## edholly (Feb 24, 2014)

It seems a couple of years have gone by and no one has come up with a Vee Twin 2 stroke design.

I have been playing around with some drawings and yes I see that a 90 degree Vee Twin has only half the crankcase pumping as a same capacity single - however a 60 degree Vee Twin has 75% the pumping so it is 50% better than a 90 degree. Maybe not so good a looking or quite as good for balance - but at 75% efficiency - maybe it could be made to work ok.

If any other of you are still out there and interested would like to hear your comments.

Thoughts are to make it somewhere around 4cc - maybe an Owen Mate with an extra cylinder stuck on - common crankpin - common crankcase - front shaft induction - slightly staggered cylinders although one might get in the way of the other won't know till I've drawn it ... actually just looked at my "Mate" and put a 60 degree template behind it and it seems to fit ok ... 

Another thing maybe restrict the "front" cylinder's transfer ports so it doesn't rob the second cylinder of all the crankcase gases...

Any thoughts ?

Ed


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## barnesrickw (Feb 24, 2014)

I just started looking into V configurations for two strokes.  There are some new designs, based on old designs that seem impressive.  One is for a v-4 2 cycle snowmobile drag engine.  



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## edholly (Feb 25, 2014)

Just did some sketches of the Mate - it is too short in the conrod to allow a 60 degree twin ... the cylinders clash by 6mm and also the pistons would too.

So cast around at a few more designs and one engine I built is a Mills 1.3 which is a really nice running motor - so looked at seeing if it could be adapted - and the answer is I believe - yes - no clash of cylinder bottoms or pistons.

Anyone else out there that thinks a Mills 1.3 could be converted to a 60 degree twin ?

Have scanned the relevent plan pages that will show what I think means it would be ok.

Maybe a reed valve induction on the crankcase would be better than under piston induction ?


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## Niels Abildgaard (Feb 25, 2014)

Hello Edholly

You are headed in the wrong direction.

If You have an afternoon or two for learning the true shining ligth of two stroke scavenging read here.

http://www.pit-lane.biz/t4072p840-g...-by-mr-jan-thiel-and-mr-frits-overmars-part-3

Jan Thiel and Frits Overmars are the fathers of the final and best 125 ccm engine.
They are NOT caring much for crankcase volume but a lot for exhaust port and tube.It is the very short and supersonic blowdown that do the pumping.
Apart from starting that is.

90 degree is the best angle .
Problem is how to make a crankshaft with counterweigths.


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## Hopper (Feb 25, 2014)

Or do a bit of Googling around on Yamaha and Suzuki V4 and V2 two-stroke racing motorcycles of the 1960s-80s.

They basically built some of them as two or four single cylinder engines coupled together, so each piston has its own crankcase to itself. Could be done on a V2 by using offset cylinders with seals in between, all on one crankshaft with a centre bearing. 

Or two crankshafts geared together on two "singles" joined at the hip.

Take a look at the Suzuki RGV250 Gamma engine. Beaut little V2 stroker.
Exploded diagrams of the entire engine are here
http://www.cmsnl.com/suzuki-rgv250-1989-k_model14005/partslist/FIG-03.html#results

For model purposes I imagine it could be made air cooled instead of liquid.


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## barnesrickw (Feb 25, 2014)

I just made a connector bushing to do a V-twin from old .049 parts.  Works like the Suzuki engine as far as the crankcase goes.  Didn't know that at the time, so thanks for posting.  


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## Slimey1 (Mar 26, 2014)

gbritnell said:


> A v-twin 2 stroke could be made. Before the demise of the 2 stroke street motorcycles there were many twins and triples out there. What you would have to do is offset the cylinders enough to separate the crankcases internally as a 2 stroke gets it's feed through the crankcase for lubricating purposes.
> If you go with a 4 stroke V-twin I have drawings for the one I made. It has a bore and stroke of 1.00x1.25 inches. It's overhead valve with and open valve train. It has pressure oiling to the rods and cams.
> gbritnell


This is beautiful.
How much would you want for the plans?


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## battiwallah (Nov 2, 2018)

Here is a photo of my Chenery 15cc vee-twin engine.  I have it running with glow plugs.  The carburettor is a design of Colin Jones (ME Plan PE31).


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## edholly (Nov 2, 2018)

.
Here's a couple of 60 degree Vee Twins I made a few years ago - the ML Midge based one uses a blade and fork conrod with opposed cylinders and Owen Mate one uses offst cylinders. Both have a common crankpin. The larger one is very powerful, seems there isn't the power loss expected as the down coming piston of No.2 cylinder supercharges the crankcase pressure and the No.1 cylinder makes more power than if a single, the No.2 cylinder gets a lot less charge as a result of decreasing pressure in the crankcase as the No'1 piston is now ascending - but it runs superb. The little one makes only enough power to sustain itself.


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## Aerostar55 (Nov 5, 2018)

AlfJones said:


> Hello all.
> 
> My grand plan of getting new toys ( new, much bigger mill and lathe ) and then launching straight into a loco build, and a rarely built loco at that, is, I think, perhaps a little TOO challenging a way to get to know my new toys.
> 
> ...


Model engine builder magazine published Drawings for the Hoglet V Twin


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## neil_1821 (Nov 9, 2018)

I agree with Aerostar55 regarding th hoglet V Twin. I think the back issues are around $14 and it’s nicely laid out and relatively simple to follow for a first engine. There are a few threads knocking around, have a look in the showing them, finished projects section of the forum.


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## abby (Nov 9, 2018)

Has anyone tried to build a miniature Wulf twin ? Villiers had plans for this engine when they were taken over by Norton but the development was dropped in favour of Norton's wankel type engine.
The Wulf has stepped pistons , the charge is drawn into the bore of the larger diameter and transfered to the opposite upper piston.
This allows a larger charge than normally aspirated 2 stroke and also allows a fully lubricated bottom end.
I believe the engine has been further develped by Bernard Hooper engineering Ltd and has found military application as a power unit for flying drones.
It would make an interesting model project.
Dan.


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