ESE's works engine tuner

**speedpro** · 26th February 2013, 11:56

Should probably put some oil in Rob's gearbox then going by the noises it was making when Av came into the pits.

**F5 Dave** · 26th February 2013, 14:36

Bit of that going around, my 50s clutch bearing was looking pretty dry, sadly I'd drained the oil into a large sump container so not sure how much came out (it was pouring out then I walked away). Time for crank seal leak test.

**jasonu** · 26th February 2013, 14:38

Originally Posted by F5 Dave

Yeah I was just remembering Jase was supposed to be in NZ by now? Pity you couldn't have been down this way for the NI round 4 at Kaitoke.

I was planning on going to the Manfield back track but it was cancelled. Not enough hours in a month to see and do everything.

**jasonu** · 26th February 2013, 14:42

Originally Posted by cotswold

Take note he is looking forward to the next GP

Probably because it isn't on a big track...

**no mates** · 26th February 2013, 15:21

Originally Posted by jasonu

Probably because it isn't on a big track...

I will take any size track now fellas, problem identified and solved
no mates

**husaberg** · 26th February 2013, 17:43

sorry i couldn't resist

Welcome aboard Nigel tell us about the bike, RG125 sleeved to 100?

**Yow Ling** · 26th February 2013, 18:07

My brain is not big enough for this, but there are people here who have brain mass to spare

Borrowed from another place in the ether
"I found some very excellent software at Autodesk. It is a beta test of Computational Fluid Dynamics (CFD) software. It is a wind tunnel simulation. This is a stand alone program so you don't need anything else. Very unfortunately the beta test runs out on March 15 next month. Fortunately there are still almost three weeks to play with it. This is very easy to use software with no math required at all. You may insert models in 2D as simple JPEG or PNG shapes or as full 3D models from just about any software. I use Sketchup and export the 3D model as an STL file. There is a free plugin for that. It works perfectly.

The program is Falcon and is available here: http://labs.autodesk.com/utilities/falcon"

Here is a link to the source http://bbs.homeshopmachinist.net/thr...tion-using-CFD

Should be good for keeping you up at night

**no mates** · 26th February 2013, 19:33

Originally Posted by husaberg

sorry i couldn't resist

Welcome aboard Nigel tell us about the bike, RG125 sleeved to 100?

RG150 with a RG250 barrel to get it down to 56mm then a steel sleeve to get down to 50mm
currently 98cc
motor is six years old now
numbers by Wob ( port timing, head shape, pipe dimensions)
assembly by me (when its broken, or Wob when its taking lap records apparently)
have had i bit of bother with nippin up on tracks where you spend a long time wide open, But I (if it fails, or Wob if it doesent) reckon its cured now
been on dynos anywhere between 23 and 28.3 hp, power from 8500 to 1200, nice flat easy to use neddies.
mid eighties RS125 chassis with standard rear end and undermaintained front end

Nomates

**koba** · 26th February 2013, 20:07

Originally Posted by no mates

I will take any size track now fellas, problem identified and solved
no mates

Haha, nice.

I have identified my problem, time to try and solve it. Perhaps I should start by smacking myself in the head...

**crazy man** · 26th February 2013, 20:13

Originally Posted by koba

Haha, nice.

I have identified my problem, time to try and solve it. Perhaps I should start by smacking myself in the head...

we have all done this . to far advance or lean

**koba** · 26th February 2013, 20:19

Originally Posted by crazy man

we have all done this . to far advance or lean

The headsmack come from me knowing this BEFORE I WENT OUT!
I had checked the plug, looked a bit hot, asked Dave for his experienced opinion and he said go richer.
I knew it, I dismissed it thinking; ahhh it's not that far off and BOOM!

I've always bee conservative in jetting and timing but was starting to push things further as I thought I was too prudish.

Lesson learned!

**Neal** · 26th February 2013, 22:31

@ Koba - what plug were you using ?

**Forgi** · 26th February 2013, 22:37

Originally Posted by wobbly

Now we have the tools to accurately predict the correct blowdown needed for a desired power output, then of course we get people wanting to go "to big " , as always, more must be better.
When the blowdown is too big for the engines tune, then all that happens is the mid power drops dramatically.

Re the 75% nozzle "rule ".
This works in most cases very well, but of course it is based as I said before on the effective total Exhaust area.
Basing the nozzle on the Ex ,that is in effect irrelevant, is dumb - but is all we have at this time.
If the Ex area is large, then 75% of large is too big.
If the Ex area is small - compared to the strict calculated numbers for STA, then the 75% may in fact be too small.
This hasnt happened to me yet, as most people havnt started to fill in the bottom corner radi, or raise the port floor, to reduce the duct volume and or reduce short circuiting, thus making a very small port.
But the few engines that I have done - like Rossi 125 hydro outboards, work very well with a small port, HUGE aux , and 75% nozzle.

Thanks for your detailed explanation!

Well of course the '75% rule' depends on the shape of the exhaust port...it is obvious, it could be too much or too little but I think that the ideal size could be determined only by testing.

As I didn't have my own observations I have shaped the blowdown according to Blair's recommendation. It seems that it works, but I haven't tested it yet. If you have any experience or result please let me know, I'd be grateful!

**koba** · 27th February 2013, 05:26

Originally Posted by Neal

@ Koba - what plug were you using ?

B10ES

I wad a 9 before that, the only change I had made was going to a Ten.
It was a hot day and I started shifting erlier before one high speed corner and pulling through under more load, at lower revs, than I had been before.