ESE's works engine tuner

[cotswold]

Can any one give me the cylinder stud spacings for their water cooled 50's, I have a project engine I am playing with and it has a 70 kit I want to ditch and replace with a 50, mine has studs spaced square 52mm. Also the original 50 cylinder is fuel injected into the head so also want to ditch that, already have the case set up for reeds.
Thanks

[TZ350]

Interesting project. tell us more .....

[cotswold]

Interesting project. tell us more .....

When I find a cylinder I can make fit I hope to build a lazy mans 50cc race bike using a recently bought SR50 motor. It has some go faster bits, Engine currently has
-Malossi 70cc cylinder
-Malossi crankshaft
-Malossi ecu
-Malossi aluminium piston
-Malossi multivar kit
-Malossi drive belt

All after market bolt on scooter bits but want that pesky 70 kit gone

[jonny quest]

If I'm reading this correctly, your issue is off idle performance after a wide open run. Does that have nothing to do with a single injector trying to cycle at 15k?

[Flettner]

Attachment 321134

My side injectors are aimed across the transfer ports to hopefully get some fuel into both the A and B ports.

Attachment 321132

Hard to do on an air cooled motor. But I would have prefered to have my injectors vertical and spraying against the air flow as I think this is the best way to get good mixing.

I think this is Flettners YZ250 cylinder. It only has injectors in the B ports but it runs Ok, in fact very well. The difference between a YZ250 and my 125 is that the YZ is running E85 and less than 9,000 rpm. Above 9K seems to take 2T EFI onto another level of complexity.

No, the YZ runs petrol and yes it's all over at 9000 rpm.
The F9 runs E90 and it also signs off at 9000 rpm (not bad I thought for and old 1973 shit cylinder) but yes not more than 9000.
My new 360 EFI engine has the injectors across the cylinder as you have done TZ, plus one up it's back port

[sonic_v]

Can any one give me the cylinder stud spacings for their water cooled 50's, I have a project engine I am playing with and it has a 70 kit I want to ditch and replace with a 50, mine has studs spaced square 52mm. Also the original 50 cylinder is fuel injected into the head so also want to ditch that, already have the case set up for reeds.
Thanks

AM6 cylinders have 52mm square. Still plenty of 50cc aftermarket cylinders though some are coming with a 40.00 mm bore instead of the standard 40.30 mm. This might be useful if your stroke is longer than the am6 39.00 mm.

[TZ350]

If I'm reading this correctly, your issue is off idle performance after a wide open run. Does that have nothing to do with a single injector trying to cycle at 15k?

15k was Rileys EFI 2:1 injector example my engine tops out about 12250 rpm.



So no, I do not think so, the injector performs perfectly at max load and rpm. The running problem is when the injector is asked to deliver fuel for less time than the transfer duration.

The only suspicious issue is the minimum injection on time. I may have it set to low, I have it set to 1 ms. On over run the map calls for 1.15 ms. so basically 0.15 of fuel delivery time. But if it really takes a minimum 1.4 ms to open the injector then its short 0.25 ms and if I set the minimum on time to 1.4 ms then the injector can't be turned down enough and over fuels by 0.25 ms.

[dark art]

The only suspicious issue is the minimum injection on time. I may have it set to low, I have it set to 1 ms. On over run the map calls for 1.15 ms. so basically 0.15 of fuel delivery time. But if it really takes a minimum 1.4 ms to open the injector then its short 0.25 ms and if I set the minimum on time to 1.4 ms then the injector can't be turned down enough and over fuels by 0.25 ms.

Is there any way to ajdust the ECU so the injector only sprays on alternate cycles, like a foul-stroke?
May not be the best solution but maybe enough to verify if the problem is minimized, it will four-stroke anyway....

[MotleyCrue]

I've been searching the World Wide Web, but haven't found anything, which I'm surprised.

Looking for some pipe specs for a NSR250 MC21. Stock, or aftermarket.... even both preferably. I don't have bike yet, so I can't do any measuring, trying to get a good start on how I want to dimension out the 2 into 1 I'm going to build for it.

https://youtu.be/hGAR539cmAs

I have never been able to get this lovely sound out of my head, I will gladly lose some HP to have my NSR sound like this.

Banshee 2 into 1 is the only 2 into 1 I have ever heard that sounds like that. Wobbly messed around with 2 into 1 engines of some sort and Banshee engines too I think, so maybe he knows why they sound like that but many other 2 into 1s dont. The Banshee 2 into 1 pretty much sounds like NA F1 engines did.

[Frits Overmars]

I have never been able to get this lovely sound out of my head, I will gladly lose some HP to have my NSR sound like this.

You will lose power but I'm afraid you'll get nothing in return. The NSR is a 90° V-twin, isn't it? You can forget about the nice sound then.
In a normal expansion pipe there is one strong pulse between exhaust opening and exhaust closure, followed by a second, weaker pulse between exhaust closure and exhaust opening with a somewhat lower frequency because of the lower gas temperature and the accordingly lower speed of sound during this second phase.
But if you couple the exhaust ducts of two cylinders that fire 180° apart, all pulses in the pipe will be identical and the sound will be quite musical.
And talking about musical, you might want to find a sound track of a four-cylinder König boxer engine with two 2-in-1 pipes.
3-in-1 pipes on Suzuki and Kawasaki triples also sounded lovely, but also at the cost of quite some power.

[cotswold]

AM6 cylinders have 52mm square. Still plenty of 50cc aftermarket cylinders though some are coming with a 40.00 mm bore instead of the standard 40.30 mm. This might be useful if your stroke is longer than the am6 39.00 mm.

Thanks Sonic, that is what I was hoping for.

[jonny quest]

Yes, the NSR250 is a V. I thought it still fired 180, I don't have motor in front of me yet. But I suppose that would be hard if the crank pins are 180deg apart, and motor is in a V configuration.

[mr bucketracer]

15k was Rileys EFI 2:1 injector example my engine tops out about 12250 rpm.



So no, I do not think so, the injector performs perfectly at max load and rpm. The running problem is when the injector is asked to deliver fuel for less time than the transfer duration.

The only suspicious issue is the minimum injection on time. I may have it set to low, I have it set to 1 ms. On over run the map calls for 1.15 ms. so basically 0.15 of fuel delivery time. But if it really takes a minimum 1.4 ms to open the injector then its short 0.25 ms and if I set the minimum on time to 1.4 ms then the injector can't be turned down enough and over fuels by 0.25 ms.

are you running a tps on it?

[wobbly]

The NSR and RGV and RS250 all have the pins inline at 0* so fire the cylinders at 0 - 90 as per the V angle.
Honda made the later RS250 GP bike 72* I think, but the crank has an odd pin offset , so I cant remember if that is an odd fire setup.
I Have fitted Ignitechs to several of them,and ground off 3 of the 4 trigger lobes to make them work correctly.

And yes any 180* twin with 2:1 reving its tits off sounds like a screamer, but no matter how good your pipe skills are you wont
get the overall power that two will.
It has been shown to create good bottom to mid power - but if the twin pipes were redesigned for that power range, then they would make even more down there.
And in the work I have done on the 180* 2:1 pipes the best result was with the Ex at 200*, so that limits its applications.
And then there was the idea of cutting the pistons short over the exhaust port.
This made a shit load of extra power - but would be impossible to jet without fuel injection or pumper carbs.

[jonny quest]

This isn't going to be a track bike. Bottom and mid are good advantage.

So do I press apart the centers and rephase for 180 firing. I wonder how bad crank harmonics would be, and how complicated it would be to change ignition to fire correctly