ESE's works engine tuner

[Yow Ling]

OK while you guys have been debating the merits of MMC, Ive been in the shed messing with my dyno, assembled the drum tonight, very hard work for a feeble office worker. data box and bits should arrive tomorrow

[husaberg]

your threads gone viral TZ
Av's a hit also it seems.

Someone must know something about the Barker Headless is it a uniflow?

[Yow Ling]

Someone must know something about the Barker Headless is it a uniflow?

It appears not to be a uniflow just 2 normal 2 stroke engines sharing a common combustion chamber , hence the 4 exhaust pipes

http://thevintagent.blogspot.co.nz/2...ery-racer.html

[husaberg]

It appears not to be a uniflow just 2 normal 2 stroke engines sharing a common combustion chamber , hence the 4 exhaust pipes

http://thevintagent.blogspot.co.nz/2...ery-racer.html

Not so sure but who knows about the normal configuration a few split singles had 2 exhausts (i think).

It appears to only have 2 crankshafts. Plus the crankcase looks narrow?. Interstingly the pic i posted came out of the classic bike mag they quoted in the replies to the blog.It looks like the blog was from NZ.

If I remember correctly (1926 is some time back) the Garelli 350 Competizione was a split single allright, but unlike the later DKW split-single racers it did not have forked or articulated conrods. The Garelli was a normal 360° (both pistons rising and falling simultaneously) parallel twin with three transfer ports in the left cylinder and two exhaust ports in the right cylinder. Both cylinders shared a common combustion chamber. Each piston commanded two carburetters. Also unlike the DKWs, the Garelli had no auxiliary pump cylinder or blower of any kind.
I do like the look of the Garelli's exhaust pipes. It is the oldest bike I know of with such modern-looking pipes. Using diffusers to promote suction was not yet common practice then, and adding end cones would be regarded as revolutionary 26 years later! But I suspect that neither the exhaust timing nor the blowdown time.area of the Garelli did the end cones much justice; they were probably shaped like this just to accomodate the fish-tails.

The Garelli is a real oddball split single. Most are tandem cylinders with either two rods or a forked rod. the garelli is side by side with a very long gudgeon pin. You're looking at the right hand cylinder which has the inlet ports at the bottom and two exhausts - one at the front of the cylinder and one at the back. No problems doing that as the transfers are all in the other cylinder.
So - sucks in on the right hand pot, transfers in the left hand one from a common crankcase , common combustion chamber , exhausts from the right hand pot as it's transferring fresh mix up the left barrel.....
Wob would approve of the long blowdown possible - and the uncontaminated fresh charge.
Frits - I see we overlapped - no factual differences which is pleasing - and no, I'm not old enough either.

[TZ350]

OK while you guys have been debating the merits of MMC, Ive been in the shed messing with my dyno, assembled the drum tonight, very hard work for a feeble office worker. data box and bits should arrive tomorrow

Its great to see this project coming along, with all these dynos being built, Buckets is getting serious.

[TZ350]

I have been using EngMod2T to try and develop a new engine plan that will give lots of over rev but I get this shape of graph and it is something I have seen on the dyno too.

There is a power peak and then the beginings of another peak, whats that about? I have tried different exhaust/transfer and inlet STA's and opening points. The changes move the second peak around but nothing I have tried blends the two into the one long curve that I want.



I suspect the pipe, the header and diffuser sections are in the ball park %%% wise but are they too steep? What should they be.

[Brian d marge]

OK while you guys have been debating the merits of MMC, Ive been in the shed messing with my dyno, assembled the drum tonight, very hard work for a feeble office worker. data box and bits should arrive tomorrow

I hope the drum will be mounted to the frame, a little bit stronger , Im not sure what you have in ming , and I couldnt see it from the photos

Stephen

[wobbly]

The pipe is a complete mess both % wise and taper wise - not even close to being too steep - as an Aprilia pipe is 124 or so diameter.
And expecting an engine to make serious power up at 14,000 with a 196 Ex port is a "pipe "dream.
The dip in power is due to a big mismatch in spec,that is synergistic at some points , but self cancelling at others.

[Neal]

Where can I read some info on squish area ratio ? I have ordered some vhm heads and would like to experiment with them . What is the best compromise - 50% ? 40% ? 30% ?
Thanks

[F5 Dave]

Dentist drill update

Well I've made an interface using an old bit & a washer welded to it & grind to shape. It drives well.

The weak point is the bevel drive inside the dentist unit so I'll have to be careful not to get it hung up or push too hard. But so far it is a success & quite easy to use, these cheapo bits seem to work well in the liner so when I have time I'll lower the transfers, but first tickle up worked well & seemed to shift some material.

something a bit like this, price seems to have gone up, but the free shipping helps. Avoid ones with too small a bits.

http://www.ebay.com.au/itm/Dental-Lo...item256de251b8


[edit] Spent a couple of hours yesterday lowering some transfers 1.2mm & it worked a treat. I did bit side at a time in case it failed, but was still going strong & happy with the result. I just noticed this morning a bit of a ridge at the interface of the cut but I'll bend a riffler a bit more to ride that bit off.

They may or maynot have a limited life, but they are cheap enough, its a pity there isn't an easier way so you could replace the heads in case one wears out as you could buy a set of 3 for $78. the way I have it I'd have to make some careful cuts & reweld.

[wobbly]

Short answer re squish in a race engine - 50% and the minimum clearance just short of the piston hitting when in overev.
ie 0.65mm in a 125 is safe at 14500.
I have seen a 100cc ( 50 by 50 ) with 0.45mm rev to 16000 and not hit.

[ief]

I was under the impression mr. Darcy knows his stuff as well...

and was curious what the exhaust did on my sim. Not to shabby if you ask me, red line is the last (I think, bin a while) exhaust I 'made'.

edit, one more try, shortened the mid a couple of cm's... darcy2

[F5 Dave]

Not wanting to take this too far off track, but a true story & I wonder if you could Sim this?:


This morning I was sitting on the throne waiting to ablut (if that is a bone-fide shortening of the word ablution - and I'm Verbing a Noun) either way I felt a sneeze coming on.

Ah
Ah
ACHOOO. instantly followed by Bududududduda.

Oh, I guess I'm done.

So the exhaust port was opening but just preceding this event the intake was violently expelling a pressure relief, but still there was pressure to expel the exhaust charge.

It was most confusing.

[TZ350]

shortened the mid a couple of cm's... darcy2

Good tip, I will try it.

[husaberg]

Not wanting to take this too far off track, but a true story & I wonder if you could Sim this?:


This morning I was sitting on the throne waiting to ablut (if that is a bone-fide shortening of the word ablution - and I'm Verbing a Noun) either way I felt a sneeze coming on.

Ah
Ah
ACHOOO. instantly followed by Bududududduda.
Oh, I guess I'm done.
So the exhaust port was opening but just preceding this event the intake was violently expelling a pressure relief, but still there was pressure to expel the exhaust charge.
It was most confusing.

I disagree. I fact i think you are talking shit. Was that your Friday musical interlude?

The dip in power is due to a big mismatch in spec,that is synergistic at some points , but self cancelling at others.

This mismatch is seen in some highly tuned 4 stokes with sometimes 3 sets of peaks and throughs.All corresponding
It is this reason i believe you see interesting things like the 2 different bell mouth lengths on Honda CBR400r's which is if i am not mistaken is the factories attempt to mitigate/Balance the resonance effects. compromise.
I seen somewhere where they tried for short bell mouths and then 4 long ones results the to top end and bottom power were as expected, but the peaks and through moved and got larger as well.