ESE's works engine tuner

[jonny quest]

I tried Klotz Benol 30 years ago for some reason. It's not good for cold weather, but it smells good and really seems to work well. No bridged exhaust port wear compared to other oils. And I don't drill the holes in piston for bridge lube.

[peewee]

benol works good in methanol and nitro . maybe its not the cleanest stuff but thats not something i ever cared about

[Henrik Y]

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Hi Henrik Y. Thanks for posting your Suzuki GP project. I loved the hand shifter modification your made that makes riding easier for you.

Here are some of the details about our gear box conversions....

I've bought a 110mm kart rod for 15mm/20mm pins to fit the vespa pistons. I don't feel like messing with the crank and try to bore it out as that can easily get screwed up with alignment and such so instead I'm grinding the crank pin down to 19mm on the ends. And while doing that I also make it eccentric for an extra 1,7mm stroke. The aluminium sleeve to the right is used for final dimension polishing with polishing compound.




I received the RG125 gearbox and it looks very similar to the GP125 gearbox. The splines are a little longer on the clutch side so might need a spacer or something but that remains to be investigated further. The selector forks seem to fit as well, might have to take of a few millimeters on the base that slides on the pin for clearance on one of them. It has the same style of clutch push rod so no drilling needed.
Instead of spacing the whole engine apart I'm thinking about cutting the wall with the bearings and reweld it further out and then modify the left side of the case for the selector drum. Instead of the oil plugs spring pin to hold engagement points against the drum, the RG drum has a "sprocket thing" slid over the left end so will have to build something there. If the selector drum wasn't cast iron I would've welded up the right side and drilled holes just like the GP drum but oily cast iron could become a cracking mess so I rather avoid that if I can.

[peewee]

nice project henrik. i once had to use a larger crank pin in a smaller hole and thought of machining down the ends but decided against that for fear of it shearing. a shop bored the crank wheel holes larger and its worked great so far. i hope you have no trouble from the pin

[Henrik Y]

nice project henrik. i once had to use a larger crank pin in a smaller hole and thought of machining down the ends but decided against that for fear of it shearing. a shop bored the crank wheel holes larger and its worked great so far. i hope you have no trouble from the pin

I will make sure to have a small radius along the transition and polish it so there's no scratches that could induce any cracks. There are eccentric pins being sold and used and I haven't found anything about them failing so I'll give it a go.

This was a first test piece and that's the raw grinding and leaving scratches like the in the corner might be a bad idea.

[F5 Dave]

Yup easy to do. Was very careful with radius etc.

Broke twice when on long tracks. Bored out and used bigger pin.. problems over. Find a decent toolmaker.

[peewee]

well if your forced to use a step pin maybe youll be ok if you put the biggest radius you can into the step. a matching radius in the crank wheel should help to get a large radius on the pin. but a sharp step i think is very risky

[speedpro]

I had a stepped pin made which lasted until I retired the engine. Started with a blank and ground 20mm ends with a 22mm centre with an offset to reduce the stroke. I cant remember the material but it was heat treated once complete. I rebuilt the crank after the bearings failed but the pin was still good.

[HenkS]

since weare discussing oils, don't know if it's available down under but since i use Putoline RS959, i haven't had any engine failure in 15 orso years. use it in my KR1S on the road and track, in my KDX200 and in my MX-mopeds.

Putoline RS959

[wobbly]

Stepped pins can be made to be reliable , but its so much easyer to use a CNC spark errosion process.
A good operator will know what copper electrode size to use and can adjust the current to get a dead straight sized hole on exactly the correct stroke.
Ive done this several tines now , with only one hole being a little tight.

Edit - its really good for destroking , as you make the new hole on center , but oversize , and use a spacer sleeve to re establish the press fit.
That way the actual new hole size is immaterial , as long as they are all the same.
Depending upon the flywheel OD lengthening the stroke this way could make the web too thin above the pin hole.

[ken seeber]

DCI update:

So, with ever so many distractions, have made up a dyno and run it with a standard ARC kart engine, with just the one pathetic carby...

Next is the all important run with the 3 carbies and see if the whole thing is a winner or a failure.

The actual dyno can provide any amount of absorption capability, but is a real prick to get steady readings, ie to hold a constant speed.

However, given this lack of control, I can sort of get any reading/result that I want..

[TZ350]

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2Stroke Stuffing makes progress on his eddy current dyno:- https://youtu.be/9IcUQfxCCUo

[jfn2]

Hello Frits:
In working with your scavenging concept drawing, I want to check my leading and trailing direction angles in an old school cylinder, and try to adjust as necessary. The engine is similar to a TZ 350 twin. It was mentioned earlier that the TZ 350 "A" port leading directional angle was to large and therefore allowed too much short circuiting. The angle I come up with for this engine is 55*. The engine I'm working with has a leading directional angle of 53*. Pretty close. In your concept drawing your example shows a leading directional angle of 30* for the "A" port and it shows it intersecting the bore center line +/- 3/4 of the way down the bore center line from the exhaust port side of the cylinder. When drawing things out on paper, for my engine, the 30* angle line doesn't hit the bore center line until past the 3/4 mark. I went back to your drawing and measured, from the drawing, the 'leading distance' from the center point on the bore center line to where your 30* line intersects the bore center line and came up with +/- 22% of the bore dia. Drawing this up using my engine bore of 62mm dia and using the 22%, I came up with, instead of a 30* angle, a 37* angle. My question is...... Is the angle more important or is the placement of the intersection point with the bore center line more important? I hope I was not too confusing.
Also could you explain a little more about the 'sum' of the axial scavenging direction degrees and how that is measured?
Thank you, jfn2

[JanBros]

my simple brain (compared to Frits') says :
not only look at the leading/trailing angles, but also the position of the port in the bore. consider exactly the same port, but if it is positionned closer to the exhaust port, it will need sharper leading/trailing angles to intersect at the same point on the centerline in the bore than a port that sits further away from the exhaust port.

you can play with this in my excel, where you'll see that changing the "center location" of the port also changes the intersecting points.
in the end, the angles themselves are not so important, but the combination of your STA-numbers and the angle of the scavenging column are what matter.

excel : http://users.telenet.be/jannemie/Jan...oke%201.2.xlsm
"manual" : http://users.telenet.be/jannemie/Jan...oke%201.2.docx

[flyonly]

Ignition timing for a 50cc being tuned for top end only. Where should it end up? I know it’s a combination of many factors and it’s a balance of them all but I expect there is a target of everything was optimal.
Looking for any advice/guidance. Not sure if I should use less of the data points in the first half of the curve. It doesn’t start to produce until 11.5k till 14.25k



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