ESE's works engine tuner

[Frits Overmars]

Frits, intake length, how short is too short?

Zero would be fine. But like Wobbly says, you need a bellmouth.
I do not bother with getting inlet harmonics in sync with rpm. Any harmonic higher than 2rd will be too weak to do much good and low harmonics require a long inlet tract. Strong harmonics can also severely mess up the carburation when at certain revs a pressure peak position coincides with the carb needle jet position,
pushing the fuel down, back to the float bowl. So halleluja once again for injection.
I prefer to keep the gas column in the inlet tract as short as possible so the crankcase can start inhaling without having to overcome a lot of column inertia, as soon as case pressure drops below atmospheric - that would be around 10° after BDC at max.torque rpm.

I was thinking about the rear disk the other day i seem to remember Wobs and Frits and Jan saying the Conrod was in the way and disrupting the flow a lot i guess a heck of a lot near or near bdc and likely more at TDC. But if the cylinder was on more of a forward angle like say a Rumi or even the classic Aermacchi layout wouldn't that lessen the issue? OK not as good as the rear disk but helpful? ....likely not i guess as the fatter part is still disruption maybe a Alpha or Ariel Arrow like hollow section rod shape

The conrod being in the way in a side disk engine was the main reason for Jan to design the rear disk Aprilia RSA125. Tilting the cylinder on a side disk engine will not change anything because the inlet opening in the case has to correspond to the transfer passage in the case and the transfer cut-out in the piston skirt.
I don't think I am familiar with the Alpha or Ariel Arrow like hollow section rod shape you mention. Have you got pictures?

[Flettner]

Thank you Frits / Wobbly / Husaberg
The set up on my new engine puts the cylinder as far forward as I can in the frame so there is not a lot of room forward to run a disc or reed for that matter ( frame tubes in the way ). Exhaust is pointing rearward so not a lot of room there either. Side inlet is handy for my application. I can run the bell mouth straight onto the rotary valve housing, straight portion of the inlet at say approx 10mm long. Crank is running reverse.
Yes maybe missing an injection shot or two might not work, I'm keen to try anything to help " hook up" and help old people like me ride better

[husaberg]

Zero would be fine. But like Wobbly says, you need a bellmouth.
I do not bother with getting inlet harmonics in sync with rpm. Any harmonic higher than 2rd will be too weak to do much good and low harmonics require a long inlet tract. Strong harmonics can also severely mess up the carburation when at certain revs a pressure peak position coincides with the carb needle jet, pushing the fuel down, back to the float bowl. So halleluja once again for injection.
I prefer to keep the gas column in the inlet tract as short as possible so the crankcase can start inhaling without having to overcome a lot of column inertia, as soon as case pressure drops below atmospheric - that would be around 10° after BDC at max.torque rpm.

The conrod being in the way in a side disk engine was the main reason for Jan to design the rear disk Aprilia RSA125. Tilting the cylinder on a side disk engine will not change anything because the inlet opening in the case has to correspond to the transfer passage in the case and the transfer cut-out in the piston skirt.
I don't think I am familiar with the Alpha or Ariel Arrow like hollow section rod shape you mention. Have you got pictures?

Neither can I.

I was just looked at some Van Veen and Kreidler and took another look at the animated GIF and seen the obvious as well

What i described as hollow may be a misnomer (they might not be but they feel that light one would think they are) section rods were made By alpha as part of there Villiers replacement bottom ends. Herman Meier used something similar on the Arrow he for for the IOM Ariel kept it on the production arrows as it was cheaper to make and worked better. It is obviously better suited to the rear inlet which is a shame. but i think a streamlined rod wouldn't do much harm.........

I had had a look for pics this is the best of a bad bunch i am afraid.
The rod profiling is also mentioned in either or both tuning for speed and Speed and how to obtain it.


Seen this while looking..... well worth a look 3 cylinder water cooled 200cc Yamaha and the rotary sleeve QUB250


EDIT

I went back and looked for a picture and guess what same conversation 18 months ago even the ignition on the Pulse and RSA thats twightzone stuff.

EDIT EDIT just noticed the balancer position missed that previously

Oval and knife-shaped conrods are better streamlined and meet a little less resistance when cutting through the contents of the crankcase. But I doubt whether they have any structural advantages.

The notch in the crankweb triggers the ignition. There's a Hall sensor at the crankcase looking at the crankshaft circumference. That gives a more accurate timing signal than a sensor looking at the end of a swaying shaft.
Below are some pictures of the Aprilia RSA125; the red arrows indicate the ignition sensor.

That notch for timing reminds me of one of the cleverest triggering setups I have seen.
In the SwissAuto/Pulse flying web engine there were two magnets at 180* in one crank web with only 1 sensor, setup much as the pic of the RSA125.
I spent ages trying to figure out how it worked, untill one day I grabbed another magnet and discovered that each one inside the crank
was orientated N & S pole outward.
The trigger sensed the N pole as cylinders 1,3 and the S pole as 2,4, bloody clever and as simple as it could be made.

[dinamik2t]

Those pics where from Jan's facebook profile, along with his comment.
At the time I used the img link from facebook and as the link changed or the photo was deleted/transfered in a different album, the old link wouldn't work.
Anyway, here are some of them, as I don't remember the Jamathi '67 and the Brno '69 photos in order to locate them in my archives.

---------------------------

Cylinder inspecting - with Giovanni Sartorato e Matteo Marini



"With my friend GJ Rigter at the Aprilia flowbench. The tool in my hand is for flowing the transfers. We flowed them with the piston in 4 different positions."



"The front half of an Aprilia crankcase. The crankshaft could be fixed in various positions by a springloaded ball. We used this for flowbench testing. We could see that the conrod disturbed the flow very much, so the idea of the rear inlet RSA was born!


Two extra:

"Giovanni Sartorato who worked with me in the Aprilia racing department"


"Alfredo, who worked with me for quite some time, a very good worker and a nice guy. Unfortunately he got killed in a motorcycle accident when going to work. We were very shocked!"

[dinamik2t]

These are the derbi pics: balancer, pick-up hall (I guess) and left-hand cover view.


Interesting story: "the photo is from 2000, when I did not work for Derbi, it was a kind of 'spying' by Aprilia! Aprilia payed a photographer for making 'spy' photo's, these were then showed in Witteveen's office. This is just one of the many...."



And two for fun.
Jan at the Garelli Halloween party


"With Luc Foekema, he seems to be burning my brain out with his hot coffiecup! () He is a very good tuner and is still active in drag-racing."

[Flettner]

I imagine that's why a twin RV both sides of the crank case might work well ( if they have to be on the side ).
The smaller the engine the worse the problem? Con rods don't shrink much as the capacity drops but room in the crank case does.

[Flettner]

The YZ 250 EFI peoject. Ready to run?

[Grumph]

No - fuel lines at least and a clutch would be nice too. The silver painted plasticine over the transfers gets a B minus.

[Frits Overmars]

I wonder what the big end bearing has to say about the reduced lubrication and cooling.

[teriks]

The YZ 250 EFI peoject. Ready to run?

If you are as fast on the track as in the shop, I think you'll podium more or less every time.

What's up with the ignition cover? -Does look a bit, unsealed, to me. If so, could get interesting in a mud race

I wonder what the big end bearing has to say about the reduced lubrication and cooling.

That too. Reminds me of an interesting FI/DI design from ArcticCat.

http://www.arcticinsider.com/Article...-C-TEC2-Engine

Dual-Stage Injection: At lower engine loads, the system injects fuel directly into the combustion chamber, on top of the piston. At higher engine loads fuel is also injected into the crankcase area and into the transfer ports, improving the fuel/air transfer time for added efficiency while also lubricating vital engine components

Slotted Piston: The unique open-window/slotted piston design allows fuel/oil mix to be injected into the crankcase area and then into the transfer ports as part of the Dual-Stage Injection design.

Key to this design is the injection of fuel (with oil) at the piston rod bearing, which a competitive DI system does not achieve (and which is known for problems).

[husaberg]

I imagine that's why a twin RV both sides of the crank case might work well ( if they have to be on the side ).
The smaller the engine the worse the problem? Con rods don't shrink much as the capacity drops but room in the crank case does.

Yeah i am no RV guru for sure the twin disk or rear would be neat but f-ing problematic i did see another design from another later motor that was similar but can't remember where it was Mirhindra or something i think

The YZ 250 EFI peoject. Ready to run?

Love milled stuff. Also must show you how to resize pics hit reply with quote

No - fuel lines at least and a clutch would be nice too. The silver painted plasticine over the transfers gets a B minus.

Hey Greg were the Alpha conrod's hollow and do you have a decent pic of one?

[Flettner]

Yes, that bloody cover! The original plastic cover fits over this, covering everything, 4.5mm wider. This is using a 450F alternator. The customer already had the unit so it had to be fitted. It will work. Not as elegant as using an alternator shown earlier in this thread.

Big end, if you look real hard there is a small port on the drum throttle valve to accept an oiler. We have a small solenoid pump that is computer controlled. There is a capscrew blocking the hole in the picture, behind the throttle cable.

Big end cooling? we will have to see how that goes. My 350 has done 50 hours with no problems.

[Grumph]

[QUOTE=husaberg;


Hey Greg were the Alpha conrod's hollow and do you have a decent pic of one?[/QUOTE]

No and no...but I have seen the inside of an Alpha rod - wrapped around a Dot frame member....what there was of it was solid.

[husaberg]

No and no...but I have seen the inside of an Alpha rod - wrapped around a Dot frame member....what there was of it was solid.

Not so Devoid of Trouble.
The old man still has two, his original 53 8E and a 60's Marcelle headed 34a or 36a

[2T Institute]

For Zeeltronic users here is the Hall Effect Sensor wiring. This method of triggering would be ideal converting reed engines to disc valve.