ESE's works engine tuner

[F5 Dave]

That's lovely I think you should use it Husa. 2nd hand all the better.

[wobbly]

Already answered the question about the Ex duct and transition point.

http://www.kiwibiker.co.nz/forums/sh...post1130882629

[F5 Dave]

Ahh yes you certainly did, I was on holiday and pretty hungover whilst reviewing that & paying too much attn. to trying to be funny & not enough learning.

I read that as - assuming a 50mm bore one would start the header proper at 100mm, with the last 25mm as the transition.

Thank you again.

And my port is too short. But I can make it up with extensions. Story of my life.

[Lightbulb]

Thanks for the chat.

[ken seeber]

A “ROUGH AS GUTS” EXPERIMENT Part 1

The question is, what happens when you:
1. Get a 100 cc ARC piston port kart engine, essentially very similar and with many interchangeable parts with the Yamaha KT100S kart engine, and connect an A port to atmosphere via a filled in passage to a flanged face. Height of the port is unchanged from the original engine.
2. However, when at TDC, there is a direct passage (something we don’t want, do we?) to the crankcase via the cut-out in the side of a regular piston
3. So we weld a small piece into this side of the piston to block it off and while we are there we’ll drill a series of holes into the rear of piston to vent thru the open piston port inlet so there’ll be no great pressure fluctuations in the crankcase


Part 2 coming

[ken seeber]

A “ROUGH AS GUTS” EXPERIMENT Part 2

4. So there’s no influence due to extraneous cylinder connected volumes in the upper cavities of the blocked off transfer passages (1 * A & 2 * B), we fill these flush with Silastic
5. Then we bolt it all together with a carb, but with no exhaust system
6. Crank it over with a few squirts of oil into the crankcase, check it out and it is all nice and oily, as one would expect with a wet sump.
7. Fill the carb with fuel only (no oil), ignition on and crank it over.

Simple really and I did say “rough as guts”.

WODDAEWESREKKON happens then?

[Frits Overmars]

when at TDC, there is a direct passage (something we don’t want, do we?)

If you keep that direct passage, the transfer windows can double as piston controlled inlet ports and you could feed a rear transfer port from the crankcase.
But since you don't want that, I assume that you wanted to completely exclude the crankcase from the mixture flow. I then also assume that there's a puddle of oil in the crankcase to keep the bearings happy. EDIT: only now did I see your second post: a puddle it is.

we’ll drill a series of holes into the rear of piston to vent thru the open piston port inlet so there’ll be no great pressure fluctuations in the crankcase.

What's wrong with pressure fluctuations in the crankcase? The built-up pressure that tries to prevent the piston from moving down, will be helping it again on the way up. I anticipate a lot of pumping losses and a lot of oil mist escaping through those drilled holes.
To comfort you, here's a picture to show you that you're not the only one suffering from ludicrous ideas .

[husaberg]

If you keep that direct passage, the transfer windows can double as piston controlled inlet ports and you could feed a rear transfer
To comfort you, here's a picture to show you that you're not the only one suffering from ludicrous ideas .

Frits if will indulge me to go back a few pages you will see I added a bit to my post 18608

There is a question in there that I think you can answer.

[Frits Overmars]

Frits if will indulge me to go back a few pages you will see I added a bit to my post 18608. There is a question in there that I think you can answer.

I saw the added text, but I did not see a question....

[ken seeber]

If you keep that direct passage, the transfer windows can double as piston controlled inlet ports and you could feed a rear transfer port from the crankcase.
But since you don't want that, I assume that you wanted to completely exclude the crankcase from the mixture flow. I then also assume that there's a puddle of oil in the crankcase to keep the bearings happy. EDIT: only now did I see your second post: a puddle it is.What's wrong with pressure fluctuations in the crankcase? The built-up pressure that tries to prevent the piston from moving down, will be helping it again on the way up. I anticipate a lot of pumping losses and a lot of oil mist escaping through those drilled holes.
To comfort you, here's a picture to show you that you're not the only one suffering from ludicrous ideas .

No puddle, just creating an aerated mixture as in Honda's string trimmer crankcase to achieve muilti angle/position lubrication. Attempted to minimize the fluctuations in crankcase as we don't have an oil scraper at bottom of piston, otherwise it'd be sealed, maybe just with an external catch tank

PS. I've always liked the SWSports engine and do concede that, basically everything has been invented before.

[husaberg]

I saw the added text, but I did not see a question....

It was more a question from the guy that created the engine.........
Why does it go better the bigger the chamber is made, did you notice how big in Gallons the surrogate crankcase was.
I have a theory as to why. but most of my theories are pretty far fetched.

[Frits Overmars]

It was more a question from the guy that created the engine.........
Why does it go better the bigger the chamber is made, did you notice how big in Gallons the surrogate crankcase was.

I had a hunch that this would be it:

We found as we increased the reciever volume the power ouput of the engine increased. We gradually increased the reciever volume until we reached a volume of 5 imperial gallons, as we would utilize any suitable container in our experiments. So by using a 5 gallon container we were pumping a volume of 150ccs into a volume of 22730 ccs which then was transferred back into 150ccs of the working chamber of the engine.

My feeling was that they only used the piston pump to draw air through the carburettor and then dumped the mixture in a huge vessel, from where the engine could breathe as if it were the atmosphere. You know, the bigger the vessel, the smaller the pressure drop when the engine inhaled (did someone say 24/7?)
I was surprised that they could get away with a 5 Gallon volume. I would have expected the fuel to drop out because of the almost stationary state of the mixture in the vessel.

[Frits Overmars]

Attempted to minimize the fluctuations in crankcase as we don't have an oil scraper at bottom of piston.

You could try fitting a reed valve inside-out at the inlet port. That would lower the average crankcase pressure and reduce the pumping losses.

otherwise it'd be sealed, maybe just with an external catch tank.

Well well well...

[cotswold]

ESE's number 1 works rider has scored herself a ride at Suzuka on board this Beast, moonlighting must be ok

[Martin1981]

Hello Everyone!

Frits and Wobbly,

i want to modify a Simson Cylinder (40mm Bore, 44mm Stroke) for daily use (not looking for big hp) and have 2 Questions regarding that:

1. Is a Combination of 150° Inlet Duration (Piston Port), 125° Transfer Duration and 170° Exhaust Duration okay or is there a Mismatch?

2. I will use a 20mm Carburetor, meaning a 314 square mm cross section area. the inlet port is 10,6 mm high and 28,6 mm wide, meaning about 303 square mm cross section area.

is it necessary or better if the inlet port area is bigger than the carburetor area? and if so, how much? i am asking because i could just shorten the piston inlet skirt to achieve the 150° duration and leave the port and it`s area alone. But what is better in your opinion? enlarging the port or shortening the piston? one could think enlargening the port is better but on the other hand shortening the piston skirt makes the edge of it stay away longer from the port and thus not disrupting the flow (if there is a flow) when the piston travells down from TDC.

Thanks in advance! (as usual, opinions of all other forum members highly appreciated!)