ESE's works engine tuner

[wobbly]

The RSA was developed due to Jan doing air flow tests on the RSW and finding that the rod position made a big difference .
Rear entry gave symmetric inflow and more power.
The engine position of the RSW was not as good as the RSA, and with more forward weight bias,many riders liked the feel of the older bikes front end, despite the RSA making more power.

[teriks]

I tried to post a little technical story here to help you through the Christmas days, but I could not manage to insert the pictures the way I wanted to...
But in case you're curious, you might want to take a look here: http://www.pit-lane.biz/t3173p657-gp...-part-2#134197

Great christmas present!
Now thats a good start on a book..

[husaberg]

My mussing is this.
On run down from high revs it will have high revs closed throttle closed throttle equals no fuel no fuel equals no oil.Plus the dyno drives the engine on longer than it would be on overun on the track.
I believe on the KTM 125 GP bike the solution was a injector to supply fuel on the Aprilia not sure. prossably a 45 kg physco rider that never backed of the throttle.They possibly did something tricky and secret...
i seem to remember Frits saying something about deto on overun as well.

Closed throttle results in no air blowing through the engine so the oil stays there, more or less. Extended run down on a dyno is never good though which is one reason they should all have a roller brake.

Can anyone remember where the KTM 125 injector stuff is?

The KTM injection was Bartols way of preventing the engines from siezing on the overev during downchanges.
Pulling 15000 + with no air, and thus fuel, and thus oil, wreaked havoc with some riders, the injector squirted fuel/oil into the case when this was occurring.

Jan Thiel has retired and the two stroke era is over so the designers dont mind shareing info, all kinds of really good info!
KTM injection well thats a strange one even though their GP two stroke program is long gone that still dont talk or release photos (press releases aside). But yes I do know how it works, supplementary injection that feds into the crankcase to richen the mixture, just another approach to a power jet.

Thank you so much for posting my Tower of Pisa-story, Husa; I think I'll stick to simpler things like two-stroke development .

Great christmas present!
Now thats a good start on a book..

Yes frits should write very many books with what i don't know.

I hit that 'reply with quote' button and then for a fraction of a second your code was visible; I just managed to take a screenshot.

I will attach a word version with the bits highlighted

The RSA was developed due to Jan doing air flow tests on the RSW and finding that the rod position made a big difference .
Rear entry gave symmetric inflow and more power.
The engine position of the RSW was not as good as the RSA, and with more forward weight bias,many riders liked the feel of the older bikes front end, despite the RSA making more power.

yes i can remember that bit (afterwards) but the building of one if one was to have a go the increase in the complexity i don't think is worth the gain.
Yes in GP the extra cost and complexity it would be worth it,but for other classes i am not convinced. Certainly not for buckets.

A technical explanation? Nah, too much to do today. But since you were kind enough to post that picture of your sex six sisters, I will show some curves of my own.
When Jan Thiel went to Derbi to design the bike we now know as the Aprilia RSA125, he encountered the 125 cc reed valve Derbi ridden by Lorenzo the previous season. Jan played around with the reed valver as well, because he wanted to find out the differences between reed valve and disk valve power. He managed to extract 2 HP more from the reed valver than anyone else had ever done before (never mind the fairy tales of reed valve 125s producing over 50 HP; those Horses must have been Shetland ponies, probably measured at the piston ring).
My graph shows the power curve for the Aprilia RSA, the Aprilia RSW and that best-ever reed valve Derbi. It's not quite in the same league as the rotaries, hmm?

EDIT: Shame on me; I discovered that I posted a wrong graph (and I do not have the correct one at hand here in Holland). Power curve DERBILOR shows the reed valve Derbi as Lorenzo rode it. After Jan finished playing with it, it had 49 HP. Still, the best-ever disk valver produced 10 % more power than the best-ever reed valver.

Rotary vs Reed =clearly worth it
Rear disk vs Side entry =not so much..ime

on the attachment bellow the arrow has slipped it should be in the column above if you hover your cursor there it will say align left ,center and align right you need to highlight the text or picture you wish to align first as well.

[trevor amos]

Very many thanks for your , in depth , technical treatise on transfer flow behavior and the controling influences , that the rest of us can only gues at . We are indeed very fortunate to have such an erudite tutor who has that rare talent to be able to offer difficult concepts and make it so accessable for us pupils !
So Frits , the only problem i can see is that we need more and more and more , and , given enough time , we might just get it ?

Warm seasonal greetings

[cotswold]

I got bored so stripped out the water cooled mb100 I bought a while ago. It was mentioned by someone that the motor may be over sized so I have put up a picture of the piston just to make sure before I decide what to do with it.
If any of you can tell by the numbers on the crown I would be grateful to find out the legality and also what it is so I can replace it. ( it has many dings looks like piston ring has exploded some time )

0.5 over
432 p2
cd

[Yow Ling]

I got bored so stripped out the water cooled mb100 I bought a while ago. It was mentioned by someone that the motor may be over sized so I have put up a picture of the piston just to make sure before I decide what to do with it.
If any of you can tell by the numbers on the crown I would be grateful to find out the legality and also what it is so I can replace it. ( it has many dings looks like piston ring has exploded some time )

0.5 over
432 p2
cd

Measure it across the skirt, 0.5 over what?

You should clear that up seeing as you named the previous owner in the photo !

[cotswold]

Measure it across the skirt, 0.5 over what?

You should clear that up seeing as you named the previous owner in the photo !

But I did clear him of any wrong doing as it was years ago he built it and as you know great grandads axe had many new heads and handles.

[Farmaken]

Wiseco listings show that as 54mm std bore +.5mm O/S = 54.5 mm

CD refers to the ring type

[husaberg]

I got bored so stripped out the water cooled mb100 I bought a while ago. It was mentioned by someone that the motor may be over sized so I have put up a picture of the piston just to make sure before I decide what to do with it.
If any of you can tell by the numbers on the crown I would be grateful to find out the legality and also what it is so I can replace it. ( it has many dings looks like piston ring has exploded some time )

0.5 over
432 p2
cd

Please note it's only called speedpros piston so I could find it in all my other junk and the piston came out of an engine he sold MANY MOONS ago and would have been changed many times since then........thought I should add that so if it turns out to be over, Rich won't be able to ramp up to Defcon 5

Measure it across the skirt, 0.5 over what?

You should clear that up seeing as you named the previous owner in the photo !

I cant tell much about that piston (is it single ring) the numbering looks kind of Wiseco like, but impossible to tell from the picture but is it forged? plain ring? dykes?
Before a motor is oversize the stroke has to be taken into consideration (Mike and i think now Dave) use larger diameter strike pistons that would be above the limit if they hadn't destoked first.

These strike kt100 pistons are readily available in a huge range of sizes and are incredibly inexpensive We all should be using them except for the cost of destoking plus the engine will be less efficient as a non close to square bore and stoke.
Simple fact is 50-50.5mm 2 stroke pistons are not really manufactured any more and it is killing wallets and engines.

Dave had what 2 or was it 3 failures with NOS yz100 pistons these pistons have not been listed by Yam since i was at school.

I doubt Suzuki still makes RG400 pistons, either that only leaves kart pistons (but all the usable size ones have Dykes rings)
and other std road bike (not generally up to it)and Wiesco which are f-ing expensive.and not available freely or in oversizes.

The 2 stroke cc limit should be about 112cc lc 2 strokes vs 155cc four strokes and i have the technical data done for the FIM to support it. Infact i intend to submit a remit to the rules based on this.

[cotswold]

Measure it across the skirt, 0.5 over what?

You should clear that up seeing as you named the previous owner in the photo !

54mm across the skirt and it has been rebuilt many times since it was sold by it's original owner as he sold it with a 6 speed box now it has 5.

It seems like I need to strip it right down to check it has been de stroked and if not look out for a standard cylinder and just run the water cooled head?

Or put it on a shelf along with all my other garage art

[Frits Overmars]

The RSA was developed due to Jan doing air flow tests on the RSW and finding that the rod position made a big difference. Rear entry gave symmetric inflow and more power.
The engine position of the RSA was not as good as the RSW, and with more forward weight bias, many riders liked the feel of the older bikes front end, despite the RSA making more power.

Fixed that for you, Wob. Typos do happen to the best of us .

[jasonu]

There are currently 65 users viewing this thread!!!

[speedpro]

"Please note it's only called speedpros piston so I could find it in all my other junk and the piston came out of an engine he sold MANY MOONS ago and would have been changed many times since then........thought I should add that so if it turns out to be over, Rich won't be able to ramp up to Defcon 5"

That's funny - Defcon 5.

The piston looks to have little dings from a broken little or big end cage, probably little end, from experiance.

I'm surprised it went to 54mm. Dave Diprose tried boring an MB out to 54mm years ago and went through the sleeve to aluminium in places.

Stock an MB of H100 is 50.5 X 49.5 for a capacity of about 99cc

With that piston at 54.5 X 49.5 gives a capacity of 115.5cc, just a smidge over the limit.

Dave has reduced the stroke to 48mm with the help of Yow Ling. His motor is now the same stroke as mine and he's running KT100 pistons around 52mm

With a piston at 52mm X 48mm gives a capacity of 101.9cc.

The cost of reducing the stroke using the method Dave used can more or less be recouped by using the cheaper KT piston and ring the first time. After that it's money for jam. Piston oversizes are in .05 steps which is just a hone which with the cost and the range of oversizes you may as well do every year, or more often.

Technically there is a few "legal" problems. Really you should use MB piston pin clips and not KT clips. I buy them by the packet of 10, MB clips that is. Dimensionally they are the same. Also the little end bearings. I've got some flash ones and when comparing them in the local friendly kart shop they look identical to KT100 little end bearings.

In case anyone is interested, I will be pulling my motor out of the chassis over Christmas some time. If anyone wants to drop round and have a look inside they're welcome.

[kel]

[QUOTE=speedpro;1130453648I will be pulling my motor out of the chassis over Christmas some time. If anyone wants to drop round and have a look inside they're welcome.[/QUOTE]

Count me in, but Im not interested in bearings. I tried having a sneaky look down the cylinder when the head was off at the GP, strangely the piston was locked at TDC. Can we take photos

[jasonu]

With that piston at 54.5 X 49.5 gives a capacity of 115.5cc, just a smidge over the limit.

.

The limit used to be around 106cc I thought. When did it change?