ESE's works engine tuner

[koba]

.8 is very conservative, I would have thought something around the .4-.5mm would be closer. If you ever need machine work done on the MB, let me know, i have jigs for machining the heads and barrels, and even one for milling the rear aux ports/reed cage in (takes about an hour to mill and god knows how long to grind!)

I'm not God but it took me about 43 hours for the first version.

Going to build a jig of my own for the aux port now that the dirty drill-press/hoary-mill conversion is complete.

Cheers all the same.

The .8 was the done-by-hand-with-few-tools version, I've now made a jig and used a lathe to get it to .6 and a better shape chamber.

I'd post some pic's but I dropped my iPhone in the shitter; post shit.

[TZ350]

My plan was to raise the barrel a fraction more to end up at around 132/198.

I'm not too sure if I should raise it further or not now, widening transfers is another option but easy to cock up; especially given my experience/tools....

These numbers are simalar to yours ...



Transfers open 114 ATDC for 132 Duration A port angled 12 deg up (Std), B port 5 deg up.
Exhaust opens 80 ATDC for 200 Duration and 72% port width.
Inlet opens 145 BTDC closes 80 ATDC 32mm equivalent dia port window, 24mm taper bored carb, 135mm inlet tract from RV to bellmouth.
Old Honda RS125 exhaust.

We got most of the improved performance from widening the rear transfers as much a possible and opening the exhaust port to 72%

[Frits Overmars]

Just love these small engines, turbo and nitro what fun.... and thanks for the link to the pullys

Here you go, TeeZee: 'small' engines, turbo, nitro and pulleys. The pulley transmission keeps up fairly well with the engine power, wouldn't you say?
http://www.youtube.com/radarruns

I almost forgot: the indicated speeds are mph .

[rgvbaz]

Here you go, TeeZee: 'small' engines, turbo, nitro and pulleys. The pulley transmission keeps up fairly well with the engine power, wouldn't you say?
http://www.youtube.com/radarruns

I almost forgot: the indicated speeds are mph .

Fuck!!!!!!

[TZ350]

Impressed ....

[TZ350]

Some on board shots from the Island.

[Farmaken]

Might be useful

[TZ350]

Add some allowance for material for a radial head nice swooping transfers and decent size cooling fins?
But are the drawings in the stuff Frits posted enough to work from?

I think this is the drawing or at least similar to that cylinder TwoTempi found in his junk box.

Its amazing what TwoTempi can dig out of his junk box.

Attachment 277728

Now if we could just hack the water jacket off this sucker and glue some fins on with a bit of weld and maybe piston port/case reed it for a good old 6 speed TF125 engine/cylinder conversion we could have ourselves something to putter around on.

Thanks for posting that, I am particuarly interested in the inside radius of the transfer ports.

Attachment 277746 Attachment 277747

The inside curves radius is important, as I understand it the wrong shape will promote flow separation, effectively narrowing the transfer duct.

I will have to look back and check on the angles but I think the transfer port (the smaller one) nearest the exhaust is angled up at 24 deg and what is the main transfer port on this cylinder which is next to the boost port and is angled up at 12 deg.

Its worth checking out Frits comments in the link below.

Frits talks about that new school cylinders transfer port shape and angles. It worth checking the original post out because Frits posted more pictures and there was quite a bit of discussion about transfer ports at the time.

A link to Yamahas paper on whats important in transfer ports. A bit older school now but its basically the shape of transfer port us Bucketeers find in our old school TZR TF TS GP engines.

[Flettner]

TZ 350 , be careful what you wish for.

http://www.youtube.com/watch?v=5DyPU...9On_IfKGD31hGA

[koba]

These numbers are simalar to yours ...



Transfers open 114 ATDC for 132 Duration A port angled 12 deg up (Std), B port 5 deg up.
Exhaust opens 80 ATDC for 200 Duration and 72% port width.
Inlet opens 145 BTDC closes 80 ATDC 32mm equivalent dia port window, 24mm taper bored carb, 135mm inlet tract from RV to bellmouth.
Old Honda RS125 exhaust.

We got most of the improved performance from widening the rear transfers as much a possible and opening the exhaust port to 72%

Cheers.

I'm at 70% exhaust at the moment and will likely soon go wider.

Widening transfers is going to be a bit harder to achieve, I'm currently mulling that one over.

[2T Institute]

Its amazing what TwoTempi can dig out of his junk box.

Attachment 277728

He has some nice stuff in there

[teriks]

So that you might be able to raise the exhaust's 'floor'.This helps improve blowdown flow, as seen on a flowbench.In 2007 we started to raise the underside of the exhaust port.The first results were very promising!But at the end of 2007 I retired, so I could not finish what I started.The idea was to raise the exhaust underside as much as possible until power dropped.
And then, with a smaller exhaust port underside it might have been possible to widen the A-ports more
without losing the fresh charge into the exhaust.

Interesting stuff, this have been around on MB40 cylinders for quite a few years. (think i got my first around 2001-2002 or so, but memory is vague.)
Great to hear the theory behind!

Even more radical things were tested I have been told, like an additional transfer port below the export floor. That did not make it to production though.

[Frits Overmars]

Interesting stuff, this have been around on MB40 cylinders for quite a few years. (think i got my first around 2001-2002 or so, but memory is vague.) Great to hear the theory behind!
Even more radical things were tested I have been told, like an additional transfer port below the export floor. That did not make it to production though.

Here it is: the MB40-6port. What is your link with MB40 engines, Teriks? Do you take part in F3D competition? If so, under which name?

[TZ350]

Widening transfers is going to be a bit harder to achieve, I'm currently mulling that one over.

For Transfers its Wobs or is it Frit's catch phrase, "wide and low" to get the specific blow down time area required (STA).

Somewhere else I read that low transfer ports work better than higher ones of the same STA.

[Frits Overmars]

... I read that low transfer ports work better than higher ones of the same STA.

The lower the transfer timing, the less risk of too-early returning exhaust pulses shoving the cylinder contents back into the crankcase.
In short: lower transfers give a better powerband, all other things being equal (which of course they never are).