ESE's works engine tuner

[mr bucketracer]

Merry Xmas to all and thanks again for all the amazing information shared on this Thread. I am sure It's made a massive difference to anyone racing a 2 stroke in NZ or anywhere across our small planet for that matter. Well done Rob!

We will be flying the 2 stroke flag again this year at the cemeterycircuit on boxing day. ( www.cemeterycircuit.co.nz ) This time with 3 bikes. 3 x NSR300's There is live streaming if you want to take a look. F3 is where we will be.


Live timing. http://www.livetiming.co.nz/Live_Timing.aspx


Cheers RB.

thanks for the link , you should do well there , love that track , next year

[nick gill]

On a personal note, I am really glad we have now got back to the important shit of discussing 2T technology...

Hi all.
Long time lurker and long time learner here (I've read all the posts), but I want to pipe up [pun!] to say thanks to all the contributers here, and especially to the fine judgement of most who know when to shut up and listen, and when to make noise. Long may the learning and sharing continue.

Wob, a few pages back you were saying the Lectron can be heavily inclined due to the layout of the idle circuit.
I've attempted to convert the Mikuni TM34SS into a downdraft with modified float bowl, pump around fuel level, and jet pick-ups. I could never get it to run lean enough although the various scavenge placements I tried all worked very well. Now suspect the idle circuit was the cause as you describe.
With your in-depth familiarisation with these carbs, can you forsee a fix for this?
Dell'orto achieved what I'm aiming for with the Gilera 125/250 Twin factory racers. Can anyone elaborate on the inner workings of these special carbs or how I could emulate them?

[F5 Dave]

Hey Rich Rich and Sketch. Good luck and see you in the pits.

[TZ350]

From Team ESE, merry Christmas everyone ...



And have fun with the gift giving, enjoy it all.



Then get on your bike, ride whatever you've got and have a great new year.

[husaberg]

Hi all.
Long time lurker and long time learner here (I've read all the posts), but I want to pipe up [pun!] to say thanks to all the contributers here, and especially to the fine judgement of most who know when to shut up and listen, and when to make noise. Long may the learning and sharing continue.

Wob, a few pages back you were saying the Lectron can be heavily inclined due to the layout of the idle circuit.
I've attempted to convert the Mikuni TM34SS into a downdraft with modified float bowl, pump around fuel level, and jet pick-ups. I could never get it to run lean enough although the various scavenge placements I tried all worked very well. Now suspect the idle circuit was the cause as you describe.
With your in-depth familiarisation with these carbs, can you forsee a fix for this?
Dell'orto achieved what I'm aiming for with the Gilera 125/250 Twin factory racers. Can anyone elaborate on the inner workings of these special carbs or how I could emulate them?
]

Two bikes I can think of and plenty of Car Carbs have gotten around this
Suzuki Wolf/Stinger
http://www.cmsnl.com/suzuki-t125ii-1...9.html#results


Humble Honda Stepthrough.
http://images.powersportsnetwork.com...CARBURETOR.gif



for the car carbs have a good look at the internals for the Webber DCOE vs IDA
http://www.racingbeat.com/images/ite...x280/16601.jpg
http://www.carburetion.com/images/weber/4-45DCOEb.jpg
or the very similar Dellotto equivients

[Frits Overmars]

I would suggest you Buy this book.

I would suggest you buy this book:

It won't tell you anything about cooling air guidance but it will look nice on your bookshelf .

[Frits Overmars]

Dell'orto achieved what I'm aiming for with the Gilera 125/250 Twin factory racers. Can anyone elaborate on the inner workings of these special carbs or how I could emulate them?

You can build your own:

[AndreasL]

You can build your own:

Wonder if a simple wedged spacer between carb and bowl on my Mikuni VM would allow for a steeper angle then the 18-20* max stated by Mikuni? Have to take a more careful look inside and see what more that might need to be altered.

Any input how to modify the VM is welcomed.

[2005bully]

Dykes rings are discussed only a couple off times and it seems they are not favorable. For one they cause detonation earlier than normal ring as I understand. Still, I'm gonne use some pistons with said rings. Now I wonder, are they more prone to 'bite' in the ex port when going to say 70 % What else should be taken into consideration?

And on a sidenote, is it a big problem if the ring-gap goes over a small port and if not, what would be considered small? (39 mm bore in this case) My thinking was if I have, say a, 7 mm wide port there no way for the ring to catch that.

Conventional wisdom seems to say that "L" shaped Dykes rings have become obsoleted by current technology. But for some applications they offer advantages over more modern rings. Their down sides are well known....Prone to detonation, tightening in the groove from carbon buildup, etc. etc,. But on the up side they require lower ring tension and generally offer an ability to pass over wider port widths. Study's of heat dissipation from the piston crown conclude that 60% to 80 % of the heat from combustion in the piston crown is transferred out through the piston rings. In light of this perhaps the improved heat dissipation of the L ring is its largest asset. An additional L ring trait, is that smaller deviations of bore size result in greater amounts of twist than with a conventional ring. Because of this it is good practice to never file down an over sized dykes ring to fit in a smaller bore. Kermit Buller

Here are a couple of links to more information.

http://www.bridgestonemotorcycle.com...ng_effect6.pdf

http://www.riken.co.jp/english/pisto...ductivity.html

[seattle smitty]

Given its quite squared-off top edge, an edge which is always tight against the cylinder wall, my notion has been that one trait of a Dykes ring (fitted so that its top edge is even with the piston crown) should be that it gives the most crisp, well-defined exhaust port opening point . . . yes? no? . . . for what that might be worth.

Maybe another trait of that type of ring, in that area by the exhaust port, is that it's harder to melt cast iron than the edge of an aluminum piston . . .

(I'm not advocating for or against these rings, just sayin' they might have a couple of useful properties. I raced an engine that had them, long ago, with no problems, but didn't "prove" anything one way or other).

[husaberg]

My own feeble understanding is the dykes ring offers a greater seal this strength is also its greatest weakness as it provides far more friction and in turn wears out the cylinder very fast.

[wobbly]

The issue you are up against is that the traditional layout dictates that the idle jet ( and its supply well ) are in front of the slide ( engine side ).
The Lectron has no idle circuit at all, with all the fuel entering the venturi up the main ( emulsion tube - but not ) needle well.
With this old school setup the fuel level for this circuit becomes progressively closer to the exit hole in the floor of the venturi, as the carb is tipped upward.
If you go too high, fuel will simply run straight up the well and dribble into the venturi in front of the slide, with no air flow needed.
To make matters worse this fuel level rises in the front side of the bowl under brakes, again fuel spews out the idle circuit without any vacuum.
Best example of this is a TZ350, where plenty of power gain is to be had by shaving off the rubber manifold face to straighten out the intake by
re angling up the old VM38mm carbs.
Go greater than about 5* and its impossible to stop the flooding under brakes, no matter how low you drop the fuel level by shutting off the float valves early.
The only way I know to get around this is to use the OEM carbs made by Keihin on things like NSR400 etc where the bowl is kept horizontal,and the venturi is angled.
People on here can tell you several other models that had the downdraft carbs from the factory - for exactly the reasons above.
The other example is an FCR as was designed for the heavily downdrafted ports on big 4T engines.
There are quite a few sizes availble in the OEM carbs used by Honda with a D shaped venturi, and the FCR is made in plenty of sizes as well, but jets for this
are a nightmare to size for a 2T.
Dellorto have made some carbs with the idle jet ( and its fuel well ) on the intake trumpet side , with drillings down the side of the emulsion tube and around in front
of the slide.They usually have a fuel adjuster screw on the side, not an idle air screw.
These could easily be modified to run seriously downdraft, as the greater the angle the lower the fuel gets in relation to the actual idle jet height.

[ief]

Cheers guys, found one of them pdf's as well. I guess they will be fine for my purpose then, street use, cast iron AC, tuned a bit.

Obsolete...hmm. nos pistons from 1965, that figures

Ok, back to engmod it is, tnx again!

[Grumph]

Most of the Dellortos made since the intro of the PHF series have the idle jet on the intake side and can be easily run at up to 45 degrees inclination.
The downdrafts pictured earlier would appear to be based on the basic PHF style bodies. Anyone got any pics of them without the bowls fitted ?

Amusingly enough, the AMAL concentric series, both 1 & 2, have the same setup and are quite good at steep downdrafts.

[peewee]

I would suggest you buy this book:
Attachment 318143
It won't tell you anything about cooling air guidance but it will look nice on your bookshelf .

i didnt know you wrote any books, especially about 4t. now if you could talk jan into writing a book . anyways what do you think about this photo ? probly wouldnt be to difficult to make something similar and plastic welding guns are dirt cheap