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Learning how to build Lotus Seven replicas...together!
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PostPosted: August 24, 2016, 7:23 pm 
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Location: No. Nevada
I've been toying with a bike engine build for a project that requires a rear mounted engine.
Originally VW power so almost any bike engine will be lighter, but also off-set.
NV DMV tells me I cannot register a bike engine car in NV, but did not cite the source of that prohibition.
Seems odd considering that the "Tahoe T" was manufactured locally, and bike powered.

They said nothing about a home made engine. :idea:
Since I like to tweak the eco-nuts when I can I'm thinking I would also like a two-stroke engine.
The old SAAB's are hard to find and only 750cc.

Anyone know of a 2-stroke top end around 500cc that is readily/inexpensively available to build my own engine from?
I'm about to get a newer CNC mill and already have a CNC lathe.
I have a spare Buick V6 crank laying around.
I've seen insane video of up to twenty-four (36?) cylinder bikes having been made.
So a 3-liter V6 should be fairly simple and provide plenty of power/revs. :twisted:

This would let me use the VW trans and clutch while also keeping the engine centered and remain lighter than a VW flat four.
Might even be possible to adapt the cylinders to a Corvair block and crank to make it even easier? :chev:
Easy to reverse engine rotation if needed too!

Yes it is a crazy idea, but I that's what I see this sub-forum as being for.

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Last edited by RichardSIA on August 25, 2016, 3:44 pm, edited 1 time in total.

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PostPosted: August 24, 2016, 9:48 pm 
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Location: Gainesville, Mo.
Have you given any thought to out-board boat motors. Big variety of sizes and HP ratings. They have been used in race cars through the years with varying degrees of success. Most problems arise from cooling issues. After all they were expected to run all day with a virtually endless supply of less-than-room-temperature water. Most recently, I've seen reports of use in off-road racers. The DMV will probably give you the "Thumbs down" on both this idea and the homemade engine because they want to see "approved" auto engines in anything heading for 'Their' highways!

GOOD LUCK!

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PostPosted: August 25, 2016, 12:30 am 
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Location: No. Nevada
Found very expensive outboards in V6 and V8, I suppose there may be V4's too?
The big high HP snowmobile engines are also expensive, like $8K!
Had some thought that if I use a production block like Corvair it's just a customized engine. :roll:
Thinking I may just title in AZ then re-title in NV. :wink:

So far it looks like water cooled Honda CR500 uppers for a custom build but the price is a bit more than I expected, X 4 or 6!
There is a V4 two-stroke race engine available that makes about 200 HP and has been used in SCCA road racing.
Company says "Racing only", price is a blank check, only available on delivery. :shock:

The apparent need to separate the throws at the crank complicates a custom two-stroke engine build.
Need to ask the guys building the insane bike engines what they did.
Now thinking to use a modified VW case for about 2.0 displacement with a billet roller crank?
Should easily make 150 - 200+ HP and rev to ?
Not sure how to mod the VW case as I know they used an odd alloy so are hard to weld.
In theory I can make my own billet cases but that is a LOT of aluminum and machine time.

May have to join this forum if I get serious about it, http://forums.everything2stroke.com/forum.php

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PostPosted: August 25, 2016, 2:11 am 
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In the early '70s I helped out my brother-in-law at his bike shop. He sold Suzukis. One of the last 2 strokes I remember was the 750 water cooled cruiser. A triple. Made decent power and at the time I thought it would make a perfect H Mod project.

Two strokes are easy to make produce gobs of HP. Just don't live all that long. A little caster oil and nitro methane works wonders.

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PostPosted: August 25, 2016, 11:23 am 
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Richard, no disrespect but you need to do a lot more reading on the subject. There are a LOT of differences between a 2-stroke and a 4-stroke engine. Just a couple of differences, 2-stokes cannot use a car type crank, they need a composite crank because there is a seal on either side on each crank journal. 2-strokes cannot use 4-stroke cases because each cylinder is a sealed self contained system. There is no open sump in a 2-stroke engine. To build an engine from nothing would be a MASSIVE project, in terms of both time and money.

Graham


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PostPosted: August 25, 2016, 1:52 pm 
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Why not rotary? :BH:

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PostPosted: August 25, 2016, 3:07 pm 
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I've had a few two-stroke engines, dirt bikes, Subaru360.
Looked at the outboard V8 crank, complex with all those dividing webs.

I have the tools to make my own crank and block if necessary.

Nothing as crazy as this! https://www.youtube.com/watch?v=McSikBdGghU
48 Cylinder motorcycle.
Funny, so far I've never seen a video of that one being ridden.
The efficiency has to be pretty poor, seems to have a hard time starting and running.

I want a very light and powerful engine, some single cylinder dirt bikes have more HP than an old VW!
Torque is another issue which seems to require larger displacement.

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PostPosted: August 25, 2016, 3:46 pm 
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If you want to do a 2 stroke you could try one of the 4 cylinder Yamaha vmax snowmobile engines. I think there's parts to get them up around 1000cc, and you can make over 200hp without going too insane. I still like the idea of an outboard though, particularly the old V8's. I think this would be awesome in a locost.
https://youtu.be/RoiWpJLokEc
Kristian

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PostPosted: August 25, 2016, 10:21 pm 
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That looks a lot BIGGER than a VW!
I'm trying to go smaller and lighter with more power.
BEC is most likely but I would like to be able to center the engine and have full size clutch.
Hard to do when it is rear mounted and short coupled.
FJR1300 uses a driveshaft so may be able to offset it a little?

I'm going to visit an MC mechanic I know to see if he knows where to find some relevant parts.
He also does boats.
From what I've been able to find marine powerheads are more expensive than expected.
$8K snowmobile engines are out of the question.
Probably better deals back east but nothing shows up here in NV.

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PostPosted: August 26, 2016, 6:09 pm 
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Look up "Alan Millyard 5 cylinder Kawasaki."

He builds some craaazy stuff with a hacksaw and a TIG welder...


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PostPosted: August 26, 2016, 8:11 pm 
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be careful with outboard V8's of yesteryear.. most of them were designed to run Vertically.

they may not have the thrust capability necessary on the crank bearings to run in a horizontal application.

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PostPosted: August 29, 2016, 8:03 am 
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FastG wrote:
Richard, no disrespect but you need to do a lot more reading on the subject. There are a LOT of differences between a 2-stroke and a 4-stroke engine. Just a couple of differences, 2-stokes cannot use a car type crank, they need a composite crank because there is a seal on either side on each crank journal. 2-strokes cannot use 4-stroke cases because each cylinder is a sealed self contained system. There is no open sump in a 2-stroke engine. To build an engine from nothing would be a MASSIVE project, in terms of both time and money.

Graham


You are quite right. Every 2-stroke engine I have seen uses the pressure in the crankcase to force the air/fuel into the combustion chamber.
Many years ago, I sketched up a two stroke that didn't.
It used a regular dry sump crankcase and a turbocharger to charge the combustion chamber. I can't imagine a simpler engine.

One problem would be starting it. Just cranking it over would probably not spin the turbo fast enough to provide pressure. I figured you could get around that by incorporating a small squirrel cage motor on the turbo shaft between the bearings. A VFD drive would spin the turbo enough to start the engine.

I don't know if anyone has tried that.


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PostPosted: August 29, 2016, 8:20 am 
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Thumper wrote:
FastG wrote:
Richard, no disrespect but you need to do a lot more reading on the subject. There are a LOT of differences between a 2-stroke and a 4-stroke engine. Just a couple of differences, 2-stokes cannot use a car type crank, they need a composite crank because there is a seal on either side on each crank journal. 2-strokes cannot use 4-stroke cases because each cylinder is a sealed self contained system. There is no open sump in a 2-stroke engine. To build an engine from nothing would be a MASSIVE project, in terms of both time and money.

Graham


You are quite right. Every 2-stroke engine I have seen uses the pressure in the crankcase to force the air/fuel into the combustion chamber.
Many years ago, I sketched up a two stroke that didn't.
It used a regular dry sump crankcase and a turbocharger to charge the combustion chamber. I can't imagine a simpler engine.

One problem would be starting it. Just cranking it over would probably not spin the turbo fast enough to provide pressure. I figured you could get around that by incorporating a small squirrel cage motor on the turbo shaft between the bearings. A VFD drive would spin the turbo enough to start the engine.

I don't know if anyone has tried that.


I think that is how the modern 2 stoke diesels work except they use a supercharger. the crankcase is not pressurized. I can't see any reason a gasoline engine couldn't work that way.

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PostPosted: August 30, 2016, 8:49 am 
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I'll just leave these here....

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PostPosted: August 30, 2016, 10:25 am 
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You are quite right. Every 2-stroke engine I have seen uses the pressure in the crankcase to force the air/fuel into the combustion chamber.
Many years ago, I sketched up a two stroke that didn't.
It used a regular dry sump crankcase and a turbocharger to charge the combustion chamber. I can't imagine a simpler engine.

One problem would be starting it. Just cranking it over would probably not spin the turbo fast enough to provide pressure. I figured you could get around that by incorporating a small squirrel cage motor on the turbo shaft between the bearings. A VFD drive would spin the turbo enough to start the engine.

I don't know if anyone has tried that.


I think every 2-stroke person has mused about this, it looks so simple. But the crank case pressures in a high rev'ing 2-stroke are a lot higher than your think. It might work for some low rev diesel engine, but nobody has ever made it work for a performance vehicle. It would be the perfect solution, 4-stroke bottom end, positive oiling, the perfect solution.

Do the maths and give it a try.

Graham


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