ESE's works engine tuner

[seattle smitty]

Who made the carburetor?

[Grumph]

Love the blown Kreidler. Have to wonder though about using a slide carb on a positive displacement compressor - throttle sticking would be a major problem. Looking at what I can see of the second carb body on the manifold I'm assuming it is a blowoff/explosion valve ?

TZee - you need to study the ducting on that thing. A leaf blower attatched to the top inlet would be cool.....

[trevor amos]

The carb looks very like the old Amal TT, the slot in the side housing of the body enclosed a brass slide connected to a handle bar lever. Moving the side up and down enabled the main jet to be adjusted by 3-4 sizes over the full travel. Damn useful in the day, primitive but effective!

Trevor

[mr bucketracer]

Thanks for all your help Rob & Cully

your bike is going good! what changes have you made

[husaberg]

The carb looks very like the old Amal TT, the slot in the side housing of the body enclosed a brass slide connected to a handle bar lever. Moving the side up and down enabled the main jet to be adjusted by 3-4 sizes over the full travel. Damn useful in the day, primitive but effective!

Trevor

Dellotto ss carbs look very similar

but in this case I am picking amal


Not so sure now second thoughts as it looks like it has a spigot rather than a flange?

[Grumph]

Dellotto ss carbs look very similar
but in this case I am picking amal
Not so sure now second thoughts as it looks like it has a spigot rather than a flange?

Pretty sure both Amal and Dellorto SS could be obtained with spigot fitting.
I've always assumed Kreidler used Dellorto's as they would possibly have been easier to obtain on the continent...
Academic anyway as the first Dellorto SS carbs were as i understand it, Amal TT's built under licence..

Interestingly, people like MZ always preferred the TT style carb with central needle as they were easier to tune on 2 strokes...The GP and RN types can be a real pain.

[Gigglebutton]

your bike is going good! what changes have you made

Hi Scott
New exhaust with a tapered section from 32 to 38mm, straightened the inlet so the card sits at 35*, taper bored that carb you sold me to 32mm.

[Frits Overmars]

Pretty sure both Amal and Dellorto SS could be obtained with spigot fitting.

Yes they could.

I've always assumed Kreidler used Dellorto's as they would possibly have been easier to obtain on the continent. Academic anyway as the first Dellorto SS carbs were as i understand it, Amal TT's built under licence.

The carb on the compressor engine was an Amal. The carbs on the roadracing engines were german Bing's, even easier to obtain in Germany than Dellorto's .

[wobbly]

In regard to the flow in a 2T transfer duct there are several points you must realise about what is actually happening.
Firstly no matter what the porting arrangement ( within the bounds of what we call normal ) there is always more pressure in the cylinder than in the case at TPO.
Thus there is backflow from the excess blowdown pressure at initial opening.
This is what makes port stagger work - the port open first flows last.
As the piston continues to drop, the pressure ratio finally goes negative as the diffuser starts to do its work as the piston approaches BDC.
Next point is that I have thought for a long time that the actual flow into the cylinder is confined in volume to that amount of mixture sitting in the duct.
There is NO actual flow from the case into the duct and then into the cylinder.
This has been confirmed with some nuclear particles - thanks to info from Frits.

So the conclusion I made ( an assumption just waiting to be revealed as an error ) was that the smaller you made the duct volume, the less its inertia
and the quicker it would accelerate into the opening port area.
Sounds good in theory but maybe not based in reality.
I did a simulation run on the RG50 I am working on now with duct entry/port exit ratios of 1:1 and 1.5 :1 - no difference at all.
The sim is using the duct area /volume/length in its calculations, so is a reflection of reality.
The total case volume remained the same - to isolate just the entry change.

So - now it looks like the duct area ratios make little or no difference if the scavenging regime is optimised to use a particular style.
Look at the B port duct entry of an Aprilia - below the gasket line from the end of the radius at the bore ,it is smaller than the port area.
Look at the A port entry area, way bigger than the port in the bore.
Of course the B port has reverse stagger and this may have an effect overcoming the small entry area, but I prefer now to believe that the duct entry
ratio has little effect, the ducts inner and outer wall shape and the exit flow angles are far more important.

Re the perpendicular B port wall with epoxy added.
That is exactly what Jan did at Aprilia to see what happened - it made more power.
Again, possibly dependant upon the scavenging regime,but in general I would expect that NOT twisting the axial flow down the duct would help in any scenario.

[senso]

I think Frits once said that when there is the need to "bend" the flow inside a transfer to only do it on one dimension/axis at a time, probably its related to your findings, there are cylinder form Yamaha(dtr 125, dtx 125, dt 200, and all the variatons of that base engine and all its cylinder models, 3MB, 2RH, 4FU) they all have a very kinky divider curved in lots of directions, the only picture that I have is from one that already had meet the burrs, but none the less its still visible that its not linear, so it might be a better bet to remove a bit more of the divider, and then fill it it epoxy and then leave a chunky divider, like the RSA so there is less turns in the duct.

[peewee]

thnx wob. for sure i think devcon is the go to straighten out the front wall of B. i had a hunch it was the right thing to do and you seemed to confirm it also. plus looking at the rsa it seems to make even more sense at keeping that wall straight up

[peewee]

I think Frits once said that when there is the need to "bend" the flow inside a transfer to only do it on one dimension/axis at a time, probably its related to your findings, there are cylinder form Yamaha(dtr 125, dtx 125, dt 200, and all the variatons of that base engine and all its cylinder models, 3MB, 2RH, 4FU) they all have a very kinky divider curved in lots of directions, the only picture that I have is from one that already had meet the burrs, but none the less its still visible that its not linear, so it might be a better bet to remove a bit more of the divider, and then fill it it epoxy and then leave a chunky divider, like the RSA so there is less turns in the duct.

seems like i read in a book one time that the duct initial entry shouldnt be made like a funell , but if so, no more than a couple degrees convergence at most. if i have questions about what or what not to do, i try to look at other cylinders with superior design. the rsa surely doesnt have any funnel shape at the very entrance to the duct. so i would assume its not the best idea to do so. you may want to try some epoxy and make a chunky divider. im doing the same as well on a banshee cylinder

[senso]

Sort of my motto, if its really good, it is used in the top competitions/racing, if not, might be old ideas or crazy ramblings.

What epoxy are you going to use if you can say?
For now I have been using Nural 21 from Pattex, its common in Portugal so I can get it in any super-market.

[peewee]

ill probly use devcon F putty. never tried it before but i have a jar of it sitting around so i might as well use it up. the green putty that jan spoke of works well in gas engines, ive used it before. dont try it for methanol though, i found it turns to rubber. if you want something that works good but doesnt cost much i would probly go with the green stuff like jan used. theres probly a handful of other epoxies that work well also

[wobbly]

Well strictly speaking the RSA does have a funnel effect, its the really big ball nose radius on the inner wall intersection with the bore.
Trust me - this is vital and makes up to 1.5 Hp in a near 50Hp 125 that previously had the usual sharp edge.
Let me remind you, the only place we see sharp edges on the leading edge of anything subject to airflow is in supersonic aircraft.
And yes, the flow into a transfer duct is seriously below supersonic.