ESE's works engine tuner

[fatbastd]

TZ's ran backwards way before 82..think BIG TZ's. Running the piston with the offset the wrong way won't make a blind bit of difference, in practical terms..BTDT.

[TZ350]

Most have an offset gudgeon pin, and mostly it is offset about 2% of bore toward the inlet side, but I have two pistons with offset of more than 4% toward the exhaust. If I use one of these, is it going to cause me grief? Actually they always cause grief, but will these be worse?

Piston pin offset theory and Engine noise reduction.

Below is a Thesis on the phenomenon of Piston Slap.



http://dspace.mit.edu/bitstream/hand...6/30012843.pdf

[richban]

Just for you Mr Wobbly.

After you bagged my first attempt head, it has been eating me up inside ever since I installed it ( not really ).

Here is the second attempt. 16:1 48% squish band .77 squish. Plug tip 5.8mm from piston top.

It will be interesting to see what happens on the dyno. The other heads seamed to be working very well. No sign of det.

[husaberg]

TZ's ran backwards way before 82..think BIG TZ's. Running the piston with the offset the wrong way won't make a blind bit of difference, in practical terms..BTDT.

This is true.

[Bert]

Just for you Mr Wobbly.

After you bagged my first attempt head, it has been eating me up inside ever since I installed it ( not really ).

Here is the second attempt. 16:1 48% squish band .77 squish. Plug tip 5.8mm from piston top.

It will be interesting to see what happens on the dyno. The other heads seamed to be working very well. No sign of det.

They have come up well, looking forward to running those up next week.
Now have your plugs arrived so we can do TPS maps???

[senso]

I was also intrigued about the desaxe layout, to apply in a 54mm x 44mm engine configuration, thinking that having the piston in the PMS after the crank as passed the 90º mark would improve the torque delivery, but to even see a difference with eng-mod I need to go crazy and put 5mm off-set in the piston.
Is it a bug, or is the "advantages" of the off-set pin something so reduced/limited?

[husaberg]

I was also intrigued about the desaxe layout, to apply in a 54mm x 44mm engine configuration, thinking that having the piston in the PMS after the crank as passed the 90º mark would improve the torque delivery, but to even see a difference with eng-mod I need to go crazy and put 5mm off-set in the piston.
Is it a bug, or is the "advantages" of the off-set pin something so reduced/limited?

Frits covered it further back........ Yamaha achieve it via offsetting the crankshaft and cylinder on quite a few modern bikes. ie YZF450
The port timing can be made asymmetric on a two stroke.
I think TZ ran the sim up to 12mm?

[senso]

Up to 4mm would be easy to do, just mill the crankcase off-set and add some guide pins, more than that would need welding, but given the over-squareness of 54x44mm its a strange layout to work with, the exhaust pipes need much different sizes when compared to a more conventional square or almost square engine, the combustion chamber is also stranger and more difficult to react to some changes talked here.

[senso]

And then there is the strange W shapped exhaust port, here with already a couple hours of work into it to gain the much needed blow-down to get this cylinder to really shine.

[Drew]

And then there is the strange W shapped exhaust port, here with already a couple hours of work into it to gain the much needed blow-down to get this cylinder to really shine.

There to hold the ring in its gove perhaps?

[senso]

Yes, without the "teeth" the exhaust port even with original specs/size would be over the safe 75% width, but they steal a lot of usable area.

[lodgernz]

And then there is the strange W shapped exhaust port, here with already a couple hours of work into it to gain the much needed blow-down to get this cylinder to really shine.

Senso, is that a Gilardoni cylinder?

[senso]

Yes, gillardoni italkit for yamaha dt 80 lc, used a lot in the dt 50 lc in Portugal, with strokes from 40mm to 48mm, there is a dozen brands and home shops doing cranks for them.

[wobbly]

So tell me whats the advantage of having 3 overheating ' teeth ' hanging down ( up ) in the Ex port over a simple 68% main port and huge Aux
to generate the needed blowdown STA.
Unless you were intent on buggering the ports Cd numbers as well as heating up the returning plugging pulse - I really dont see it.

[wobbly]

Hey Rich that head looks alot like Mr Thiels for his Aprilia, hope it works as well.
Personally I would have done a toroid, but you have the plug plent close enough to the combustion burn space
so probably no free lunch to be had.