ESE's works engine tuner

[jbiplane]

The Lambda O2 sensors are affected by oil ( and we were told - lead ) residues coating the element. We discovered in SKUSA racing with CR125 stock classes
that if it was put into a hollow threaded bung in the very front of the muffler with its tip just short of the perforated , it lasted for years and the readings were very reliable/stable.
Stuck in the belly we had nothing but problems with reliability and inconsistent readings.

Do you have any picture how correctly install?

[diesel pig]

What cylinder are you using, TZ350?

[TZ350]

What cylinder are you using, TZ350?

RG50 cylinder with the original inlet tract sealed up with Kneed-It putty. Also for the RV, the left side case was filled up with Kneed-It too before milling it flat for the rotary valve and cover.

[F5 Dave]

Um, have you not made a conventiinal boost port by cutting up to the two rear ports the and blocking the transfers from them?

[wobbly]

Here is the setup for Lambda used on the CR125 in SKUSA

[lodgernz]

RG50 cylinder with the original inlet tract sealed up with Kneed-It putty. Also for the RV, the left side case was filled up with Kneed-It too before milling it flat for the rotary valve and cover.

Rob, did you have to cut the end of the crank to fit the carb directly to that stub?

[TZ350]

Rob, did you have to cut the end of the crank to fit the carb directly to that stub?

Yes. It is also where the ignition trigger gets installed.



This is how I went about it.
I used all the rotary valve parts from a Suzuki GP125 and flywheel.
1) Salvage the crankshaft hub from an old flywheel.
2) Cut the thread off the end of the crankshaft.
3) Drill and tap the crankshaft for a M5 screw.
4) Machine the hub and crank flush. Then machine 0.005" five thou off the end of the crank to give some crush on the hub. You only just want it gently squeezed, just enough to hold it securely but easy to get off again.
5) Make a spacer with about 0.010" ten thou clearance between the hub and the rotary valve driving dog.
6) Insert a 2-3mm thick "O" ring in the face of the spacer to give it some crush on the RV driving dog.
7) The hub is keyed to the crankshaft. Screw a M3 dome head into the hub for the ignition trigger at the appropriate timing position.
8) Crush the dome head in a vice to collapse the Philips star. You need to do this so you don't get two ignition pulses close together. One from each side of the Philips dome head screw.
9) At TDC drill a 5mm hole in the crank shaft for the RV driving dog's driving pin. 5mm fitted the key way in my Suzuki RV driving dog. I cut an old drill bit down to use for the pin.
10) Used a short piece of hose and two hose clips to secure the carburetor to the inlet stub. I put a larger "O" ring inside the hose to prevent metal to metal vibration contact between the carb and stub.

[TZ350]

Um, have you not made a conventional boost port by cutting up to the two rear ports the and blocking the transfers from them?

Yes and no. We did try removing the bridge between the two boost ports. Bad idea. We have not tried the idea you suggest. It looks worth trying. Thanks for the tip.

[diesel pig]

Yes and no. We did try removing the bridge between the two boost ports. Bad idea. We have not tried the idea you suggest. It looks worth trying. Thanks for the tip.

I am fascinated. What made removing the bridge between the two boost or C ports a bad idea? I am thinking about doing something like that to a similar cylinder.

[F5 Dave]

I did this with my RG Reed valve conversion. Many years ago and cocked up as I made a mistake on the exhaust so i abandoned it. Just turned into a convential design. You would extend boost to gasket face (I did this on my case reed MB100 conversion).

[Flettner]

Foundry work, the sides go in last so as to be able to check all is in place.

[Wos]

Dear experts!

Which is minimum bridge of material between main exhaust and the auxiliary ports at a nikasil plated 40mm bore cylinder?

Does the minimum depend on bore size? On shape and cordal width of main?
How wide were the bridges for example in the rsa?

Is there a rule of thump for bridge on a FOS shape 70% cordal main Ex?

thanks a lot !

Grüße Wolfgang

[wobbly]

3 millimeters

[Wos]

3 millimeters

Hey wobbly,

Thanks for answering 😀
Do you talk from 125 cc...54 bore...rsa? 😀

Is there a corelation to other bores or technical datas? Cant belive 3 mm over all?

Another question to get a feeling what could be minimum bridge at main with auxiliary ports...

What is minimum rlieable coated surface width at a mid bridge on a butterfly ex port?

Tanks from germany to NZ 😉

Grüße Wolfgang

[wobbly]

3mm is needed as a minimum to have sufficient load area supporting the ring face with lubrication.
This works in 125 and smaller cylinders - I have seen a 50cc race cylinder with 2mm Aux bridge widths and it wore away slots in the ring.