ESE's works engine tuner

**TZ350** · 13th November 2009, 20:50

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Given up on the big carb idea, but could this work? a 24mm carb feeding into a plenum chamber and the 34mm rotary valve inlet feeding directly from the chamber to the motor. That way when the motor takes a gulp (duration 200 deg) it sucks full atmospheric pressure through a high flow 34mm bell-mouth and the restrictive 24mm carb has much more time (duration 360 deg) to refill the plenum.

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**TZ350** · 13th November 2009, 21:10

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Where we have got to after 100 pages.

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

And a collection of the better links from the last few pages, more collections on pages 80 & 90

24mm carb for 30+ hp go-cart engines posted by Sonic_V
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

Low loss venture tubes: http://www.cranemfginc.com/PDF/Ventu...0CATALOG-2.pdf thanks Bucketracer

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

Expansion Chamber Design According to Blair:- http://members.bellatlantic.net/~vze...es/expcham.htm

This http://www.geocities.com/a57ngel/moto/CDI.html talks about repairing/modifying a KDX CDI's retard curve, there is also a schematic.

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, taken from http://www.lortim.demon.co.uk/vsih/pistons.htm

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.

Some handy hints on making cables:- http://www.dansmc.com/solder_cable.htm posted by Bucketracer

It might be a 12A Rotary exhaust port but there is some interesting ideas about testing and port radiusing applicable to 2-stroke exhaust port shaping. http://www.yawpower.com/Flow%20Testing.html

Using a venture instead of a throttle plate in the carburetor to controle engine speed...........
Venture throttle:- http://www.prvperformance.com/PRV_in...l_overview.pdf

Another interesting pipe design program:- http://www.mh-aerotools.de/airfoils/javapipe_en.htm

Here is a xls spread sheet that can be downloaded that is based on MacDizzys work and covers blowdown time area:- www.essjayar.com/motorbikes/2_stroke.xls

Its a bit wordy but has some interesting ideas on getting ignitions going and lights if you need them. http://www.btinternet.com/~jhpart/bkns125a.htm

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**koba** · 13th November 2009, 22:49

Woop Woop!

Celebrating 100 pages!

**gav** · 13th November 2009, 23:05

After 100 pages would've thought he'd have an FXR150 by now and save all the stress ....

**bucketracer** · 14th November 2009, 09:29

Originally Posted by gav

After 100 pages would've thought he'd have an FXR150 by now and save all the stress ....

I think good old TeeZee (Dad) still dreams of two-stroke glory,

If he had brought an FXR150 he would have been able to watch a lot more TV.

Mow the lawns more often.......

Do the shopping.........

Spend time with the grand kids.......

Finish that second degree he started.....

Watch more of those interesting art house movies he likes......

Play solo in a friends aging punk rock band.......

Tell his wider group of friends, and especially the motorcycle ones how much he loves and enjoys them......

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**bucketracer** · 14th November 2009, 15:35

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Suzuki GP125 parts micro fiche and other things GP
http://www.cmsnl.com/suzuki-gp125-19...393/partslist/

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**Buckets4Me** · 15th November 2009, 07:39

Originally Posted by bucketracer

I think good old TeeZee (Dad) still dreams of two-stroke glory,

If he had brought an FXR150 he would have been able to watch a lot more TV.

Spend time with the grand kids.......

Tell his wider group of friends, and especially the motorcycle ones how much he loves and enjoys them......

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he spends lots of time with the grandkids every month (now push the bucket faster this time)

and he has made a wider group of motorbike friends (in the bucket community)

see you all at Mt Wellington

**Yow Ling** · 16th November 2009, 11:06

OK Ive got myself a bit confused with this Carankcase compression thing. What is high and whats low. Say for example you had a crank case of 100cc and a displacment of 100cc that would be 1:1 Is that high or low? now say you had a crank case of 150cc and a displacment of 100cc 1:1.5? the number sounds higher but the compression will be lower.

Im sure somebody can sum this up in 1 line (please)

**sonic_v** · 16th November 2009, 11:57

crankase compression ratio = CV / (CV - SV)

CV : crankcase volume with piston at tdc
SV : swept volume of piston

**TZ350** · 16th November 2009, 18:35

Originally Posted by sonic_v

crankase compression ratio = CV / (CV - SV)

CV : crankcase volume with piston at tdc
SV : swept volume of piston

Putting values to Sonic_V's formula:-

For:- CV = 300cc and SV = 100cc........300/(300-100) = 300/200 = 1.50:1 High......peak power, narrow power band

For:- CV = 350cc and SV = 100cc........350/(350-100) = 350/250 = 1.40:1 Med

For:- CV = 380cc and SV = 100cc........380/(380-100) = 380/280 = 1.33:1 Low......broad range, drivability

And as I understand it the common ratio range is something like 1.3 to 1.5

and the terms High, Med, Low, peak and broad range are all a bit arbitrary.

**Chambers** · 17th November 2009, 17:39

Originally Posted by TZ350

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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.

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Used TeeZee’s software to plan my new engine for Taupo. The software can work with either Jennings or Blairs formulas.

Picture 1, is the screen for determining port heights and durations and port time area for the power you want.

Picture 2, is the cad section where you plan your ports to get the required port time area.

Picture 3, the software prints out all the data and a pattern of the new ports.

Picture 4, from the port cad printout I made a metal template of the port shapes.

Picture 5, with the template in the bore its easy to cut the ports to the right shape and the metal template also protects the bore from accidental slips with the Dreammel.

Bet TZ wishes he had thought of making a protective metal template when he did his barrel….

.... great software, thanks TZ.

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**F5 Dave** · 18th November 2009, 14:28

Originally Posted by SS90

As a sidetrack,

These 2 pictures arrived today, I'm not 100% sure, but the cylinders are off a Yamaha from the early eighties belonging either to Johler Harald or Emmerich Stenger.

Evidently this engine was (apparently) faster than Anton Mang's Kwaka, but I havn't seen any evidence of that.

I imagine that ring life would be somewhat "short".

There are some pretty harsh marks on the bore directly above the transfers, I would surmise that is due to the "boost channels".

I'm 100% sure that it would have any gains, but it seems it may have.

I wonder if Boysen started off with this concept before ending up with the transfer boost's we know today?

Well back to this sidetrack from a month ago. (Page 95 for SS's pic) I've finally gotten to reading this Yamaha book (I got sidetracked by Kevin Cameron's TDC vol 1) ok I'm only just past first couple of chapters but there was a bit that went on fairly accurately describing this type of gullery port curving around the inlet (from memory) ". . . this type of port was first seen in the US in 1966. . ." on the Yam TD1 racers.

They were aircooled & the claim was it did help with sm.end oiling along with some piston holes as well.

Being watercooled & paired & piston port I still believe these were TZ500. Any thoughts on this?

**bucketracer** · 18th November 2009, 20:34

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SS90's cylinder pictures and some TZ250 cylinders.

I guess early TZ500 cylinders would look the same, or did all the 500's have power valves?

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**F5 Dave** · 19th November 2009, 08:27

oh lookie there, watercooled 250 cylinders with piston port inlet. I hadn't gotten to the TZ250 section of the book but I always assumed the 250s were reed once they got to that era. After all the first TZ750 was a 700 using 2 TZ350 top ends & the 750s were reed from the start, but I knew the 500s weren't.

All I can claim is I am young & ignorant

. . . . Especially the young bit.

**bucketracer** · 19th November 2009, 20:56

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Yamaha TZ500

Yamaha's smaller works four cylinder 2 stroke racer, the YZR500, or OW19, first saw competition in the 1973 French Grand Prix, won by the late, great, Jarno Saarinen. The bike had originally been little more than basically a "double" TZ250, including a rather large dose of the 250's peakiness, and had been fitted with reed valve induction to tame it's power delivery by the factory after the "Flying Finn", Saarinen, had made comment on the difficulty he had controlling this type of power surge from such a potent machine.

That first Yamaha four, measuring 54 x 54 mm, set the format for others which followed over the next decade, with horizontally split crankcases, four transverse in-line piston port cylinders, each with four transfer ports and a single exhaust, and two separate crankshafts utilising 180-degree crank throws, geared together and driving the six-speed transmission via a layshaft located behind the cranks. http://www.tz350.net/ac1.htm

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