Originally Posted by bucketracer
Reposted because someone wanted to see how the pumper was mounted. The little white hose thing is a mod for the pulse line from the crankcase. There are more photos on the original post.
Forum whore
Reposted because someone wanted to see how the pumper was mounted. The little white hose thing is a mod for the pulse line from the crankcase. There are more photos on the original post.
Forum whore
That article was only published at that German forum and nowhere else. I think it is worth the effort as it is only a short article and it will help you gain a better understanding of the events in a two-stroke engine. I'm sorry I can't find the time to translate it right now.
EDIT: Hey, the self-centering has gone. You can tell the Missus to strike that from her list, Husa.
Forum whore
I'd like to tell you about the events in the engine. Without calculating (it already expects
enough), but with logic, in a way that it can understand a 12 year old. This is just in the area
my knowledge of German.
Look at the picture some HFD-1.
There you'll see a cylinder. Above the piston is a volume VZYL and therein a pressure prevails Pzyl.
Then comes an exhaust manifold. It contains a mass of gas. The moves are not enough.
After the elbow is the exhaust volume Vout and the pressure is there Paus.
Now we consider what happens when the engine is running in thousandths of seconds. But we have
not in a hurry, we take the time to step by step to follow closely and rethink.
Case 1: The piston has just released the exhaust port. The pressure in the cylinder Pzyl is higher than the pressure
Paus in the exhaust. This means that the gas mass in the left elbow is more crowded than the right.
The mass will be accelerated on the right night. It flows from the gas cylinder in the manifold and thereby
the cylinder pressure drops Pzyl.
At the same gas flows from the exhaust manifold in volume, thereby increasing the exhaust pressure Paus.
As long as the cylinder pressure of the exhaust pressure Pzyl Paus is the gas mass in the manifold
accelerated and the flow velocity on the increase.
This goes on until Pzyl Paus is the same. Then the gas mass reaches its maximum speed.
Because the flow from left to right, ie running from the cylinder to exhaust, remains in the cylinder always
less gas left, so the pressure drops Pzyl ever. And the exhaust is it just the other way.
There is always flowing into it more gas, so that the pressure continues to rise Paus. Paus is therefore higher than
Pzyl. The right of the elbow will be more crowded than on the left and the flow in the manifold is always
decelerated more, until it completely stops.
The crowd is right now much stronger than the left, so the currently stagnant gas mass in the
Now bend to the left accelerates back to the cylinder.
The acceleration remains active until Pzyl Paus again is the same. Then the mass of gas has reiterated its maximum
Speed is reached, but this time left. After growing Pzyl beyond Paus and after the
left flowing gas mass decelerated again until it stops.
Now we are back at the starting point: the cylinder pressure Pzyl is high, the exhaust pressure is Paus
lower, and the mass of gas in the manifold is stationary. She has now performed a complete oscillation of
left to right and back.
Case 2: Imagine that the cylinder volume is now twice as big VZYL. The cylinder is so much
more gas as in Case 1 Now, if gas from the cylinder flows in the manifold, the cylinder pressure decreases Pzyl
much more slowly. So down it takes longer now to Pzyl up at the Pau-value.
It takes longer to stop the flow. And then when the flow goes to the left, back to the
Cylinder increases, Pzyl at much slower and takes longer to stop this reverse flow.
Everything just takes longer.
Case 3: Let us now before the exhaust volume Vout also made twice as large. If dan
Gas from the exhaust manifold flows in, the pressure Paus also much slower. It takes longer to
the flow is slowed down to the right and the return flow comes to the left in motion. And so on.
Case 4: Now we do the Krümmerdurchmesser much smaller, as in Figure HFD-4.
The piston is released to the exhaust port. The mass of gas in the manifold is on the pressure difference
Pzyl-Paus back to the right and accelerates the flow velocity increases again. But because
the small Krümmerdurchmessers comes despite the gas flow rate less mass per
Second from the cylinder to the exhaust. The cylinder entlehrt So slowly, the pressure drops Pzyl
slower, the pressure rises more slowly Paus, everything is slower.
Case 5: the elbow regains its original diameter, as shown in Fig HFD-1. But now
we make, such as image HFD-5 shows the manifold much shorter.
All other values VZYL, Pzyl, Vout and Pau are the same as in Case 1
The pressure difference Pzyl-Paus of the acceleration provides the mass of gas, is again the same.
But the mass itself is now much smaller! Therefore, it is accelerated harder.
The flow rate increases faster, the cylinder pressure Pzyl decreases faster and the exhaust pressure
Paus is increasing rapidly. The flow velocity reaches its maximum value is more likely, rather slowed down,
rather, the direction changes from right to left, there is also decelerated more. In short, the
whole vibration plays in less time.
Leak
Now to another topic. I have stated several times: gas flows from the manifold in
Exhaust volume, thereby increasing the exhaust pressure Paus. But even in HFD-1 image you can see the hook:
the tailpipe! The exhaust has a leak. It comes in. Although gas, but also some same time escaped.
Therefore, the pressure Paus not nearly as fast as you expect without the tail pipe like it.
The pressure in the exhaust behaves as if the exhaust volume would be larger in reality. And
the larger the pipe diameter increases slower Paus Paus, and the lower is the peak-
be. The final hole acts like a shock absorber in the system.
Far left of the images are somewhat remarkable: the overflow. Once the piston
the scavenging port releases, has not only the exhaust volume, but also the cylinder volume a leak.
The cylinder pressure drops Pzyl though because gas flows away from the cylinder above the elbow, but as soon as
Pzyl comes under the irrigation pressure, fresh gas is refilled. Pzyl decreases less rapidly so as to
closed transfer ports.
Once through the opening of the overflow valve, the cylinder volume is brought into communication with the crankcase volume,
Thus it behaves as if it were greater in reality. The vibration in
this coupled volume and tube-dan system is running slower, and the system frequency drops.
Now you have something to ponder:
An increase in volume of the exhaust system reduces the frequency.
A reduction of Krümmerdurchmessers well.
A shortening of the manifold increases the frequency.
An enlargement of the Spülsteuerwinkels lowers the frequency.
An enlargement of the tail pipe diameter reduces the frequency and weakens the pressure fluctuations in the
Exhaust.
"Instructions are just the manufacturers opinion on how to install it" Tim Taylor of "Tool Time"
“Saying what we think gives us a wider conversational range than saying what we know.” - Cullen Hightower
Forum whore
O boy, Google Translator at work, isn't it? There are passages not even I can understand. And I wrote the damn article!
Warning: translating via Google may not give you a better understanding, but it will certainly give you a headache!
Forum whore
aha but i can now understand it like a 12 year old
to lazy but was hoping someone may take up the chalange
"Instructions are just the manufacturers opinion on how to install it" Tim Taylor of "Tool Time"
“Saying what we think gives us a wider conversational range than saying what we know.” - Cullen Hightower
Forum whore
In 1970 I was doing the grand tour around NZ with a few friends on our bikes. And we visited Burt, Burt liked it if visitors brought a generous meal of fish and chips to share.
His home and workshop was two concrete block sheds side by side, each was about the size of a single car garage. The car and windmill lived in one and Bert, the lathe, workbench and bikes in the other.
We spent an hour or so there chatting and marvelling at the windmill contraption he used for a dyno, the shelf of broken engine pieces and the basic hand tools with which he made everything.
One of my friends still has a match box full of little bits of engine from Burts big blow up at Muriwai.
Pictures were originaly posted by Husaberg
Forum whore
Burts comments ”That the engine was blown up on a regular basis and new schemes to extract more speed from the engine often made it slower or just increased the pile of blown parts.” Well that’s familiar to me and probably sounds very familiar to anyone else who has tried their hand at “improving things”.
I guess there is a little bit of Burts spirit in most of us.
Pictures were originaly posted by Husaberg
Forum whore
I hesitate to compare ourselves in anyway to the great man, but Team ESE do everything with pretty basic hand tools too.
Anorak
I hope they don't have any of burts teeth mixed in
One of the trophies for Cams had (could have be recycled as the Burt Munroe Memorial throphy i guess) a pair of Burts conrods. I will post a pic if i have one.
There is a beautiful story in George Beggs book he wrote on Burt How he used to cajole people (press-gang) into helping with the paddlewheel dyno. It only worked once of course
If you get the chance, read the book. The Velo is over looked by most people, but that was just as well developed.From what i understand was the Worlds Fastest Velocette as well.
Kinky is using a feather. Perverted is using the whole chicken
Hardcore Biker
How did you find the pumper carb in comparison to a float style carburetor, Im looking at running one of these on an engine I am building to try and make the intake as short as possible as well
No8 Wire Extraordinaire
Well I'll be right into the cases with the carb mounted that close on the shortened mount. So its a project for later, there's room to dig into it so I'm not too swayed by the inconvenience.
Don't you look at my accountant.
He's the only one I've got.
Forum whore
I thought it was a very good carb and when I got used to it I found it very easy to tune. It took me a while to get used to doing very small 1/16 turn adjustments on the needles. To start with, I would rush it and mess it up.
In the end the problem with it was that as the power increased over 28+ it could not pass enough fuel to keep up, it could be modified I guess but it is now destined for a RG50 where the inlet tract is on quite a steep angle that doesn't suit conventional carbs.
I got my best run from it without any sort of bellmouth, and now think those fancy bellmouths you see for these carbs are more about somewhere for the airbox than air intake.
All the inlet you need for 28 hp.
Air cooled, 125cc rotary valve, 24mm Tillotson HL360A carb, 1979 Suzuki GP125 2-stroke engine with original (ported) cylinder.
Forum whore
Same here, because the RV cover is behind the clutch cover on the GP engine so it is a bit of a challange, not impossible just difficult and time consuming so it will have to wait till some of the other projects are out of the way.
But I am certainly going to re visit the plenum idea too as that allows for a very easy short inlet.
Was worth a crack
It will work on the KE using the standard 24mm Mikuni. I got all inspired by Fritz's very clever (why couldn't I see that myself) mounting method.Oh no ........ it was hard enough to get down to 130 and EngMod2T points to 85mm
Now I will have to look at Fritz's Idea.
So I taper bored the Mikuni, 24mm venturi 28mm outlet. Even had to do it myself as that meany TZ350 wouldn't do it. The standard inlet length is under 100mm, approximately 30mm shorter than with the PWK. With a small amount of machining the outlet will fit nicely into the valve cover spigot reducing the overall length to wait for it ... 85mm!
Hardcore Biker
Thats great thanks I am using it on an yamaha scooter and its running vertical so easy to fit. They say they dont hold tune well and are very fussy with air density changes.I thought it was a very good carb and when I got used to it I found it very easy to tune. It took me a while to get used to doing very small 1/16 turn adjustments on the needles. To start with, I would rush it and mess it up.
In the end the problem with it was that as the power increased over 28+ it could not pass enough fuel to keep up, it could be modified I guess but it is now destined for a RG50 where the inlet tract is on quite a steep angle that doesn't suit conventional carbs.
I got my best run from it without any sort of bellmouth, and now think those fancy bellmouths you see for these carbs are more about somewhere for the airbox than air intake.
It managed to support 28 hp with the inlet like this.
Air cooled, 125cc rotary valve, 24mm Tillotson HL360A carb, 1979 Suzuki GP125 2-stroke engine with original (ported) cylinder.
Rg50 does that by chance run the mineralli am6 cylinder
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