ESE's works engine tuner

[katinas]

Any idea how make simple and robust connection of 2 existing crankshafts to inline layout with minimal rework of original parts?
https://www.rrd-preparation.com/en/v...linder-2t.html

Hi, most easily dismantled construction was used on outboard Privet 350 engine.

[F5 Dave]

So if snow engine is piston port can you copy a Suzuki RM barrel circa 1980s and feed a pair of boosts from the Bs? Cut water jacket hole, then inner to make trenches, bore ports, glue back ally with Devcon/JB, then Water jacket. Must be bliss working on huge cylinders.

Or cut off inlet, graft on huge Reed and drill proper boost port? Done that before more than once.

[Niels Abildgaard]

Hi, most easily dismantled construction was used on outboard Privet 350 engine.

Do You have a clearer picture of how the screw position 8 clamps the counterweights around the shaft?
If it works well (do not loose grip) it is an elegant and cheap solution .

[Condyn]

Thank you for the replys. The specific cylinders that I am referring to are air cooled and indeed piston port. Experimenting with staggered openings may be in the future. The rules state that intake concept must be maintained. In other words, no reed conversion allowed. Feeding boost ports via the B ports is impractical in this application as I have already slightly blown thru the rear stud bores. Also already have a lot of devcon on the transfer short side radii as without it you can see the cylinder head from the bottom of the transfer ducts. They will call me Dr. Devcon if I keep it up!

[katinas]

Do You have a clearer picture of how the screw position 8 clamps the counterweights around the shaft?
If it works well (do not loose grip) it is an elegant and cheap solution .

Niels, I did not find clear picture, but found video https://www.youtube.com/watch?v=kVBOgW-o4CE from 17.47 to 22 min well visible.

[Frits Overmars]

Niels, I did not find clear picture, but found video https://www.youtube.com/watch?v=kVBOgW-o4CE

Nice engine, nice video. It left me with two questions.
1: Why the threaded plug in the crankcase wall for access to the crankshaft pinch bolt, if that bolt is readily accessible from above?
2: Why are both piston ring slots right above each other instead of spread over the piston circumference? Just because it was convenient to use one long stift, fitted from above, for both ring slots? I will admit it's KISS, but I don't think it's the best way to reduce leakage.

[Niels Abildgaard]

Niels, I did not find clear picture, but found video https://www.youtube.com/watch?v=kVBOgW-o4CE from 17.47 to 22 min well visible.

Thank You.Very clear and interesting even if I do not understand rusian.

[jbiplane]

Hi, most easily dismantled construction was used on outboard Privet 350 engine.

Thank Katinas. Yes clamping solution is elegant, but I thinking how correctly connect 2 existing crankshafts like AM6 using cylindrical shafts

[Niels Abildgaard]

Nice engine, nice video. It left me with two questions.
1: Why the threaded plug in the crankcase wall for access to the crankshaft pinch bolt, if that bolt is readily accessible from above?
2: Why are both piston ring slots right above each other instead of spread over the piston circumference? Just because it was convenient to use one long stift, fitted from above, for both ring slots? I will admit it's KISS, but I don't think it's the best way to reduce leakage.

I have no explanation for the plug hole in crankcasebut it does not cost much
Many two stroke pistons work their whole life with only one piston ring.
Maybe the second ring gives more friction than gain in power.
Worth a try by someone with a dyno and a two ring pison engine

[jonny quest]

Just put a hole in each inner crank webs, press a straight shaft between the 2

Thank Katinas. Yes clamping solution is elegant, but I thinking how correctly connect 2 existing crankshafts like AM6 using cylindrical shafts

[wobbly]

My KISS take would be to have a single , central , female sleeve that both cranks press into.
This can be any suitable diameter than the stock main bearing surfaces , as you will then need to make a central labarinth seal fitting over this sleeve to suit.

Just be aware of the problems involved with pressing a shaft directly into the middle of any crank wheel.
This internal press fit will plastic deform the big end bearing hole directly above the shaft bore, and change the stroke slightly comparred to a non pressed wheel.
Makes truing the crank impossible , unless the wheel with the inner press fit has the stroke centerline moved inwards to compensate.

[Pursang]

Thank Katinas. Yes clamping solution is elegant, but I thinking how correctly connect 2 existing crankshafts like AM6 using cylindrical shafts

By "Existing" cranks do you mean unmodified? If so, here is something dodgy, that could be done in a small workshop.



Internal thread is only intended to pull the tapers tight. Secured with loctite, vent hole to prevent pressure lock.

Countersunk screws to provide visual & mechanical access to the key-ways for indexing. (Psychological security too, maybe!)

Final indexing will require selective fit or hand finishing on one taper.

One thread will be anti rotational??, if this is a concern, shim the coupler to the main bearing on that side. (fit a bigger ID crank seal)

If reversing one crank is not an option, it might be possible to machine one internal end of the coupler flat, to lock against the drive side shaft. Engine rotation will be more critical.

cheers Daryl.

[husaberg]

Ariel arrow
as there is more than one version i guess one is better /cheaper/easier than the other.


Another option is what Aermacchi HD used.


or good old RD200


There is maybe enough material to do any three but the HD/macchi solution looks to be the easiest

[WilDun]

The Ariel Arrow taper and woodruff key was the last straw, a great example of going too far with the budget thing! - no doubt meant to be a cheap alternative to a Hirth arrangement! - the bloody thing slipped slightly (just after you set the timing!!
Also the splined shaft on the RD 200 is good of course, but how could that be cheaper than the Hirth design? - can't see it!

[jbiplane]

Thanks all comunity for advices

By "Existing" cranks do you mean unmodified? .

Very small modification like cut off shafts

My KISS take would be to have a single , central , female sleeve that both cranks press into.

Yes, I want to have conical shafts at left and right, and cylindrical crank parts fitted together. Probably thermal fit should work OK.
Or maybe loctite will make a job. May be I will need make groove in sleeve for keyhole.

Other company, my competitor make connection like this
Press fit and labyrinth sealing. But engine dont produce declared power and cranks often shift by some angle in connection.

Me making opposites with 2 main strokes 43mm+- and 52mm+-, but want try V90 and inline.
It is important to make cranks as cheap as possible and easy reparable by customer in any country using easy to get parts.
At moment I produce cranks by myself, but in small butch each crank for twin have internal cost ~250USD.
I quoted production in China on my drawings and got even bigger prices if order below 300 units.
Noone want make 10...25 custom cranks.

Contrary the price serial cranks, says:
BWS 90 42mm stroke
Simson s70 44mm stroke
Gilera Runner 51mm stroke
is just 46 USD for small numbers and 25USD in a quantity.

One strange idea - is it possible use "spline" side of crank to connect shafts using connector made of variator parts?
Or may be exist standards or drawings for splines shape? Will this connection compensate some imperfecties in aligment?