ESE's works engine tuner

[Frits Overmars]

I am interested as to what the eyes of experience would read in it.

How much time is on that piston....

Can't remember the hours on that one but quite a few

Which reminds me of the man who went to a fortune-teller to get some palm-reading done. The palmist promised him he would meet a gorgeous woman and get married. The man replied: "Some palmist you are. I got married to her allright. And divorced too!"
The palmist said: "What do you expect from me when you never wash your hands."
It's the same with spark plug and piston reading.

[kel]

I thought I read in the Pit Lane forum that Frits/Jan tried a radius on bottom of piston with worse results. I definitely could be mistaken.

You are not mistaken. It was mentioned in part two of the "all you need to know" thread

[richban]

Which reminds me of the man who went to a fortune-teller to get some palm-reading done. The palmist promised him he would meet a gorgeous woman and get married. The man replied: "Some palmist you are. I got married to her allright. And divorced too!" To which the palmist said: "Don't blame me if you never wash your hands."
It's the same with spark plug and piston reading.

Haha. Well I have been happily married to that little wiseco for over a year now. And when things are going great in your marriage, I figure its best to not to suggest she is looking old, caked in crap and needs a wash. She's getting ditched soon for a younger model.

[190mech]

I too have wondered why the rounded(ballnosed)barrel to transfer duct,yet the sharp edged piston worked well with Mr.Thiels RSA engine.If the piston is held in the cylinder and slowly lowered.the transfer ports open well before the piston skirt interferes with the barrel/duct area.I tend to think the rounded area greatly improves flow during initial transfer opening and once its at BDC the duct volume is large enough to keep good flow..Just a theory from a country boy...

[richban]

OK so now not liking this piston as much.

Mock up at BDC. Or should I say cock up? Seams to be a lot of piston in the way. hummmm.

[peewee]

OK so now not liking this piston as much.

Mock up at BDC. Or should I say cock up? Seams to be a lot of piston in the way. hummmm.

do you see in the first pic how the wristpin hole pops open at bdc ? i wonder if thats bad. maybe frits or wobbly could answer. i have the same thing happen on one of my engines, some of my other engines the wristpin hole stays covered at bdc. depends on the cylinder wall length, wristpin height etc, i guess.

[richban]

do you see in the first pic how the wristpin hole pops open at bdc ?

Yeah its almost the same on the NSR250 barrel. But not as pronounced but you just see a touch of the wrist pin. But a 59mm piston stuck into cases that are made for a 54mm piston with no skirt mods is not looking that hot. Almost 6mm either side of the skirt needs to be chopped to bring it back to how a stock honda piston sits in the case. How much more could come off I don't know. But it looks like there can be big gains in the duct.

[husaberg]

Yeah its almost the same on the NSR250 barrel. But not as pronounced but you just see a touch of the wrist pin. But a 59mm piston stuck into cases that are made for a 54mm piston with no skirt mods is not looking that hot. Almost 6mm either side of the skirt needs to be chopped to bring it back to how a stock honda piston sits in the case. How much more could come off I don't know. But it looks like there can be big gains in the duct.

Rich was this a diy 300 or a Tyga300?

The cases were a bit of a mismatch to the transfer port entry and needed a bit of cutting. It was a toss up whether to cut the cases (for top end power) or to epoxy the cylinder (midrange). I went for the former. While I was in the cases, I smoothed out all the lumps and bumps for a smoother flow.

http://tyga-performance.com/site/index.php?cPath=73_191
I see prox do a kr150 piston.

[richban]

Rich was this a diy 300 or a Tyga300?


http://tyga-performance.com/site/index.php?cPath=73_191
I see prox do a kr150 piston.

Lets just say all Tyga kits are a little (Do it yourself). I should have noticed.

The photos are mocked up with stock cases. Mine are way way different, rough F3 case copy. But still the piston skirt is a bit of a wall. The good thing is it can be fixed. In an NSR250 at BDC the piston skirt sits above the tang the same amount as the 150 piston on the 300. But obviously it is a lot more narrow and scooped away more than the 150 piston.

[wobbly]

Yep Rich you are onto the issue.
I am building 3 - 300 engines right now using a 60mm Wossner piston based on RS125 with long rods from Samarin to correct two big issues.
The piston cutout being the obvious one you have found, and the second is that Tyga machine the 150 cylinder base to get the timing ( very ) roughly
in the ball park.
What it needs is a short deck piston, and a long rod ( as per A kit ) then a spacer plate to get the case volume increased to somewhere near correct, NOT
reduced by chomping down the deck.
This way you get to increase the case vol and fix the cutout issue, and get the boost port timing correct, so the A and B can be ground up, along with the Ex to correct the idiot
blowdown STA designed in by the Thai noddy in charge of the cylinder specs.

[richban]

Yep Rich you are onto the issue.
I am building 3 - 300 engines right now using a 60mm Wossner piston based on RS125 with long rods from Samarin to correct two big issues.
The piston cutout being the obvious one you have found, and the second is that Tyga machine the 150 cylinder base to get the timing ( very ) roughly
in the ball park.
What it needs is a short deck piston, and a long rod ( as per A kit ) then a spacer plate to get the case volume increased to somewhere near correct, NOT
reduced by chomping down the deck.
This way you get to increase the case vol and fix the cutout issue, and get the boost port timing correct, so the A and B can be ground up, along with the Ex to correct the idiot
blowdown STA designed in by the Thai noddy in charge of the cylinder specs.

3? You bastard. I hope they will not appear next to me on the grid anytime soon. In the MC21 chassis they are a fun fast bike.

[richban]

( as per A kit ) then a spacer plate to get the case volume increased to somewhere near correct

Just make sure you use them very very short plugs on the bottom barrel and watch you air gap in the forks. There is maybe 10mm to play with before you would be needing to loose front fork travel.

[wobbly]

You are lucky Rich, two are going to WA the other is here as road bike using a NSR250 frame, and will only get used for the occasional track day.
Dropping the plug into the head with the toroid will help, but yes there aint no room even with shorty RS125 plugs.
The one here is really being built to stick it up the Honda Fagots on the NSR forum, whos dying belief is that if HRC didnt build it then its a piece of shit.
So the sole idea is to blitz all their dyno numbers out of the park.

[richban]

You are lucky Rich, two are going to WA the other is here as road bike using a NSR250 frame, and will only get used for the occasional track day.

Good oh. Well there will be another 2 on the track by end of the year anyway. So spill the beans what does your sim file say the HP could be?

[wobbly]

The STA says 100 Hp crank = 88 rear wheel at 11500.
The limiting factor is keeping the powervalve/port geometry correct, so it cant be ground up much.
Sorry I should have said the one here is going into an RS250 chassis.
And now that we have gone long rod the cylinder does not need cutting and we dont need a plate, so plug/wheel clearance will be helped.