ESE's works engine tuner

[ken seeber]

UHV 5

In some respects I wasn’t completely excited with the engine performance, so wanted to do 2 things before I progressed any further.

The first thing was the cylinder. It was something left over that was junked for one reason being a hole through the bore to the outside world. I did fill this with Devcon, but as you can see that this wasn’t lasting and was externally seeping. So, created a new liner (we fortunately had some spare blanks kicking around) with exh and inlet ports only.



The other thing was the nature of the flow coming from the 3 petals. Are we getting a nice pancake mixture descending slug or is it some high velocity swirl motion around the outside of the bore, perhaps not displacing the centre exhaust gases?

So, with a bit of 3D printing made up the rig in the vid so one could see the valve movement and also maybe get an idea of the gas motion.

https://www.youtube.com/watch?v=iceFOIRa6Fw&t=8s

The problem with bloody 2 strokes is that, when “off the pipe”, there is always exhaust gas remaining in the cylinder. The scavenging streams are intended to both displace this as much as possible out the exhaust, and not itself escape out the exhaust and also, remain stratified enough to ensure there is a combustible mixture at the plug. Each and every cycle = a 2 stroke that 2 strokes.

So, the plan is to observe the 3 petal flow plus try some other alternatives that I have ready to go.

In some respect it could be treated like a Jante rig, but I don’t think that this is a great system. Interestingly the Jante rigs I have seen used a fixed piston and air being blown thru the crankcase, whereas in this case, the flow will be derived from a motored engine.

More to come.

[TZ350]

hey tz . What did the port timing of your stort stroke bucket engine end up been .just building my one

Shortened Suzuki crank to 48mm stroke and NSR250 54mm bore cylinder. Packed up the barrel to get transfers opening 116 deg ATDC and that positioned the exhaust opening at 80 deg ATDC without any additional porting required.

The shorter 48mm stroke has the effect of increasing the blow down time area on the NSR cylinder that originally had a 54mm stroke. As the short stroke crank needs to turn a lot more degrees to get between Ex opening and Trans opening.

We did this conversion with a basically stock Suzuki GP100. A little later closing on the Rotary valve (80 deg ATDC). Used the original Suzuki GP carb and inlet tract. Honda RS125 NF4 pipe. Made a strong 25 RWHP. With another engine (my EFI bike) and a lot more work (and much more crankcase volume) we have managed a good 30 RWHP.

[jfn2]

Hello everyone:
This question is not necessarily related to two stroke or four stroke but to dyno building. If this is not the right place please move it. I was looking at the post that Frits put up with the picture of the bike on a dyno and I noticed in the background was a second roller and shaft up against the wall and it looked different then the one on the dyno. I thought it looked a little smaller in width. And I thought, how does a person know what MOI to design into a roller for a certain size bike like a 125cc MX or a 250 roadracer or a 50cc moped or a 1100cc road bike? I have a inertia dyno with a 355mm dia and 406mm length. How can I figure out what size bike this was designed for and how much weight to add for a bigger size bike or different application.

[Frits Overmars]

how does a person know what MOI to design into a roller for a certain size bike like a 125cc MX or a 250 roadracer or a 50cc moped or a 1100cc road bike? I have a inertia dyno with a 355mm dia and 406mm length. How can I figure out what size bike this was designed for and how much weight to add for a bigger size bike or different application.

You do not need to change the inertia; adjust the gearing so that the bike on the dyno goes through its power band in the same time as it would do on the track.
That is the nice thing about inertia dynos; they allow you to develop an engine for the exact circumstances that it has to perform in.

[jfn2]

Frits
Thank you very much for the response.

[Haufen]

Hello everyone:
This question is not necessarily related to two stroke or four stroke but to dyno building. If this is not the right place please move it. I was looking at the post that Frits put up with the picture of the bike on a dyno and I noticed in the background was a second roller and shaft up against the wall and it looked different then the one on the dyno. I thought it looked a little smaller in width. And I thought, how does a person know what MOI to design into a roller for a certain size bike like a 125cc MX or a 250 roadracer or a 50cc moped or a 1100cc road bike? I have a inertia dyno with a 355mm dia and 406mm length. How can I figure out what size bike this was designed for and how much weight to add for a bigger size bike or different application.

If I remember correctly, when the roller weight is double that of the bike+rider, then the acceleration time will be like on the road for every gear.

You can find further info and a nice excel spreadsheet on roller design on the sportdevices homepage

[TZ350]

Thanks for that . Mines even shorter stroke again but good to see ratio difference From standard Nsr to yours . Just need to find that now

Suzuki GP125 Bore 56mm stroke 50mm ratio 1.12: 1

NSR MC21 Bore 54 stroke 54 ratio 1:1

De stroked Suzuki GP with NSR cylinder Bore 54mm stroke 48mm ratio 1.12:1

So these 110cc hybrid engines have the same bore/stroke ratio as the original Suzuki GP's. Which was not ideal but worked well enough.

[mr bucketracer]

Suzuki GP125 Bore 56mm stroke 50mm ratio 1.12: 1

NSR MC21 Bore 54 stroke 54 ratio 1:1

De stroked Suzuki GP with NSR cylinder Bore 54mm stroke 48mm ratio 1.12:1

So these 110cc hybrid engines have the same bore/stroke ratio as the original Suzuki GP's. Which was not ideal but worked well enough.

mines 44.8 stroke and 56mm bore . Cr80 is 45mm stroke . As a starting point I will set the exhaust at the same hight as a cr80 and go from there . Just will keep machining the head to drop in the barrel as I lift the barrel

[TZ350]

mines 44.8 stroke and 56mm bore . Cr80 is 45mm stroke. Just will keep machining the head to drop in the barrel as I lift the barrel

My guess is you are going to use a RGV250 twin cylinder or better yet a 30hp std Aprilia RS125 road bike cylinder with reed valves. That would be my choice. I could not de stroke far enough for 44.8mm. I would have had to sleeve the pin boss and re bore it. That was beyond me so I take my hat of to you.

[Myron]

Sorry Will,Looks like Rotax is still using a stupid expansion chamber with their Turbo engine!!WTF??

Stupid expansion chamber? Could you explain?

[mr bucketracer]

Thanks tz . It has a rgv barrel on it but have a tzr to try and also a hole aprilia engine which I may short stroke and build a frame for as the drive is on the other side. Not really my thing as a true bucket engine but is within the rules . Guess I need all the help I can get lol

[F5 Dave]

What we really need is an early Mito. Only because it has 7 gears which seems impossibly exotic (but in reality is just another gear).

[TZ350]

Aprilia engine which I may short stroke and build a frame for as the drive is on the other side. Not really my thing as a true bucket engine but is within the rules .

Yes. we took a good look at an Aprilia engine but back then we could not de stroke the crank. Otherwise we would have used it for sure.

[JanBros]

Stupid expansion chamber? Could you explain?

I agree with your question mark.

I don't think I'd be still interested in a 2-stroke without an expansion chamber, even if a turbo would make it a better engine.

The moment the pipe begins to sing is THE haleluya-moment of riding bikes. and I hate flat torque-curves, they make bike-riding boring.

[WilDun]

I agree with your question mark.

I don't think I'd be still interested in a 2-stroke without an expansion chamber, even if a turbo would make it a better engine.

The moment the pipe begins to sing is THE haleluya-moment of riding bikes. and I hate flat torque-curves, they make bike-riding boring.

But you haven't heard one with a turbo, when you do, then you can decide which is better!