ESE's works engine tuner

[Bert]

.



Attachment 223503

Cylinder bore damage.
.......

Years at 70% without any problems, and now at 75% this has happened twice recently.........

lunched piston hummm, I've seen this before. is gap set correctly for the temperature you are running at?
Interesting that only one side of bore has worn the brunt of the damage (melted piston). mine (TF) use to do this; the port (through its lead up shape and port face shape) directed slightly more gas to one side of the port (and around the piston into the transfer); so i assumed that this was heating up the piston unevenly?? i attempted to slightly reshaped the entire port length (though i can't confirm that it made any difference)..
I also noted that your port on that side of the bore looks rather square cut (might be the photo, though looking back it seems to show up in other older photos). is this putting uneven pressure on the ring? resulting in ring stress and hammering that you are seeing..

your piston, lunched (not nicked) i bet you that sounded funny when it happened... I hope you didn't do to much damage to the roof of your exhaust port?

as for your retard curve, I would have thought that is wasn't retarding enough (resulting in extra heat), I would have though that 8-10 degrees would be a mark to aim for (as seen with MX's & RS125s systems). but in saying that I haven't had any of my bikes on a dyno for years to see how well my CDI works..

[TZ350]

GP125 18+ rwhp: skim the barrel 1.5mm and “o” ring it, thin alloy spacer plate under the barrel and Suzuki RG250 pipe. Ex opens 86 deg ATDC and Trans opens 114 ATDC, std head , inlet timing 145/55 and carb mj 95.

GP125 20+ rwhp: skim the barrel 1.5mm and “o” ring it, thin alloy Spacer plate under the barrel and Suzuki RG250 pipe modified to RM125 specs, KX80 ignition. Raise the exhaust to open 83 deg ATDC, and widen to 70% of the bore, cut 30 deg from the closing point of the rotary disk, so inlet opens 145 BTDC and closes 85 ATDC. Set the mj 105 and ignition timing, 26-28 BTDC using a dyno.

Pipe dimensions Suzuki RM125 B/C page 82 Bell http://www.kreidler.nl/artikelen/per...raham-bell.pdf

Save the stuffing around and go buy one of these digital, programmable ignitions
http://www.ignitech.cz/english/aindex.htm originally posted by K14

The engine........



To fit an RG250 pipe all that is needed is to cut the header flange off, modify it to fit the GP cylinder, bolt it back onto the cylinder and weld the pipe back in place at the right angle and fit a new back mount on the chamber some place, real simple.



It turns out that the front of an RG pipe is the same dimensions as the RM chamber we want for the 20+ option.

The old 18 rwhp RG250 pipe with the front section cut off.........



The new 20+rwhp RM copy chamber made from part of the old RG250 one compared to an original RG250 pipe.




A dyno graph of the 20+ rwhp option, red line fixed KX80 ignition blue line IgniTech programmable ignition.



The above mods will pull 20+ rwhp from a GP125, Ned's manages 23 after these simple changes.

The key is being able to get some dyno time to set it all up.

Bucket and Thomas managed to get some Dyno Vids of Ned's bike which is pretty much the above specs, with maybe a little more exhaust duration.

The Vids can be seen here............

Running up NedKellys RS/GP125 on the dyno

[TZ350]

Sure, good chambers are developed on dynos by people with lots of experiance...blar blar blar.....

But most of us don't have a dyno and have to start some place........

This is my XL spreadsheet for the basic design of an expansion chamber, based on work by someone who undoubtably knows their stuff......... this is a good place to start and then develop from there if you have the $$$$ and time........

The spread sheet......

Chamber Design Spread Sheet.....xls

And the Maths...........

[bucketracer]

.

Bert has a very extensive links list........... http://www.kiwibiker.co.nz/forums/gr...cussionid=1489

Some links from this thread:-

Port/Time/Area Jennings page 81-82 http://www.vintagesleds.com/library/...20Handbook.pdf

Pipe dimensions Suzuki RM125 B/C page 82 Bell. http://www.kreidler.nl/artikelen/per...raham-bell.pdf

If you want to plan your ports using Jennings or Blairs methodology then this very good and inexpensive software is just the ticket. http://www.porting-programs.com/ makes it very easy to get the true total and mean port areas of the transfers.

We see that the flow bends upwards and forward towards the exhaust port as the cycle proceeds and the piston rises to shut the port.
Abstract taken from http://www.lortim.demon.co.uk/vsih/pistons.htm

Prof Blair on the design of an intake bell mouth:- http://www.profblairandassociates.co...mouth_Sept.pdf

IgniTech programmable ignitions for race bikes
For 2-strokes get the SPARKER DC-CDI-P2 race http://www.ignitech.cz/english/aindex.htm because it is has all the bells and whistles

KartWeb Tech Articles
www.kartweb.com/TechArt/2Stroke/chapter1.doc
www.kartweb.com/TechArt/2Stroke/chapter2.doc
www.kartweb.com/TechArt/2Stroke/chapter3.doc
http://www.kartweb.com/TechArt/2Stroke/chapter1-2-3.swf
http://www.kartweb.com/TechArt/2Stro...technology.htm

24mm carb for 30+ hp go-cart engines
Carb-01 http://www.out2win.com/catalog/images/ibeal5.jpg
Carb-02 http://www.out2win.com/catalog/ibea.html
Carb-03 http://www.j3competition.com/downloa...mologation.pdf

http://www.tz350.net/tz250page.htm portmap for the TZ250 from 1976 to 1984.

Some interesting info on hydroformed expansion chambers from Bert.
I though it might be useful; if it hasn't been posted before.
http://ypvsbox.free.fr/pipedesigner_en.html
and this
http://www.gifford.ca/hydroform.html

The specs of Avalons Team ESE's BOB Suzuki GP125 20 rwhp engine:

Skim the barrel 1.5mm and “o” ring it, no head gasket, thin alloy spacer plate under the barrel and Suzuki RG250 pipe modified to RM125 specs, KX80 ignition. Raise the exhaust to open 83 deg ATDC, and widen to 70% of the bore, cut 30 deg from the closing point of the rotary disk, so inlet opens 145 BTDC and closes 85 ATDC. Champher the inlet side of the crank at 45 deg to aid inlet flow. Set the mj about 102.5 105 107.5 and ignition timing, 26-28 BTDC using a dyno. A link to Bells book and the RM pipe specs can be found on page 100 of this thread.

Cheap easy effective mods that most anybody can do and get 20+ rwhp from a Suzuki GP125.

Forced convection and micro bubbles........
Check it out here:- http://www.liquidcooledairpower.com/lc-ridofheat.shtml

Plenty of links to other interesting items to read on pages 80-90-100-110-120-130, 140 Etc..

[TZ350]

A bit of info from Yamaha on Transfer Port Shapes.........

[TZ350]

.

Chambers is back from the Doc's and Team ESE now have 2 broken collar bones after the 2-hour.............

We were out to ride a clean race so are very pissed off.........

[Henk]

Short word, starts with F

[SS90]

lunched piston hummm, I've seen this before. is gap set correctly for the temperature you are running at?
Interesting that only one side of bore has worn the brunt of the damage (melted piston). mine (TF) use to do this; the port (through its lead up shape and port face shape) directed slightly more gas to one side of the port (and around the piston into the transfer); so i assumed that this was heating up the piston unevenly?? i attempted to slightly reshaped the entire port length (though i can't confirm that it made any difference)..
I also noted that your port on that side of the bore looks rather square cut (might be the photo, though looking back it seems to show up in other older photos). is this putting uneven pressure on the ring? resulting in ring stress and hammering that you are seeing..

your piston, lunched (not nicked) i bet you that sounded funny when it happened... I hope you didn't do to much damage to the roof of your exhaust port?

as for your retard curve, I would have thought that is wasn't retarding enough (resulting in extra heat), I would have though that 8-10 degrees would be a mark to aim for (as seen with MX's & RS125s systems). but in saying that I haven't had any of my bikes on a dyno for years to see how well my CDI works..

I agree 100% Bert, my opinion is that the square exhaust port that the standard GP125 is cursed with my well be the other limiting factor in the design (the first being the odd crowded rear transfer arrangement.)

Still, more that 22 PS from one is respectable, by any standards, it would just seem that the time area is now limited by the width you can go, meaning the only option is more duration (bummer)

Perhaps the best option in the quest for power would be to machine out the cast in liner on a lathe, and make you own liner to suit.

Not as hard as it sounds, and you can be very certain your scavenge patterns are what you want before fitting.

[Bert]

Bert has a very extensive links list..........

some stolen from Team ESE and Mr SS90...

[bucketracer]

some stolen from Team ESE and Mr SS90...

I think TeeZee is pleased you have grabbed the better ones and added them to your collection and that you have made it open for all to read.

Yes the square GP port is a problem, 70% did not allow much rounding of the window, 75% was as much about improving the shape as increasing port time area.

TeeZee and Chambers are talking about drilling in little side exhaust ports, the feasibility of it has been the topic of conversation around the lunch room table lately.

[SS90]

TeeZee and Chambers are talking about drilling in little side exhaust ports, the feasibility of it has been the topic of conversation around the lunch room table lately.

I have seen a guy here try that a few years back, on a cast iron cylinder, but I am unsure that it really worked as hoped, I cant see you ruining a cylinder if it doesn't have a real effect...... I say go for it.

How much time area would you gain by having a 70% port, and auxillery exhaust ports as big as the space allows? That would be the answer to if it worked or not.

I have had some concepts about auxillery exhaust ports explained to me, and the crux of it was that not all calculated auxillery exhaust port time area is applicible, and the main advantage is not time area as such, but rather improvement of scavenging of the exhaust port when the piston is halted at BDC... better for touring engines than racing engines.

But for sure, auxillery exhaust ports increase time area, just not as much as you wold expect. (remembering that 80% of the exhaust gasses escape as soon as the exhaust port cracks open, rather than exiting in a controlled orderly linear fashion in response to opening time.)

[CM2005]

Poor cully, no wonder he was so sore thats a nasty break!!!!

I have the answer to all our problems, let us use a bloody 28mm carb or something!!!

[TZ350]

we did 168 laps, which was 67km lol epic considering the bike was in bits 2 hours before the race with oil everywhere, broken cases, no pipe or bodywork.. hah
4th to last in the race,and i binned it twice!! Crashtastic! Need more ground clearance!!

You and Pete did very well just getting out there, and then doing 168 laps, good effort..........

[TZ350]

as for your retard curve, I would have thought that is wasn't retarding enough (resulting in extra heat), I would have though that 8-10 degrees would be a mark to aim for (as seen with MX's & RS125s systems). but in saying that I haven't had any of my bikes on a dyno for years to see how well my CDI works..

Hi Bert, this is my first time playing with a programmable ignition, so not very sure what the limits are......

[koba]

How are you guys powering the ignition units?
12v battery?