ESE's works engine tuner

[Muhr]

Are we still talking DLC? The toughest honing stones I know are diamond. And what did the D in DLC stand for? So if there are places where you don't want the DLC, masking seems the only option.

Well, I was general in my statement. anyway i agree that honing a dlc surface will be a problem. Making a start and stop on the thickness of a DLC coating will be a challenge in itself regardless of the material, and nothing I would choose to try. however, to cut off eg 0.5mm from a dlc coated part, I can not say is impossible as the material behind will give way.

[Flettner]

Yeah love to see an update on this.

Although dirtbikes are evil. Well mine is.

Im suitably ashamed of myself.
It means nothing but it felt good just to hear it bark a few times.
The plan is to have a dirt bike that is not evil, just fun but I still want max top end, you know, because you can never have too much top end on a dirt bike, aye, especially a 360cc rotary valve.
Interesting, the short bursts it did do, the throttle mechanisim worked.
https://youtu.be/bhKrRlZxomc

[wobbly]

Well done Frits , but to me Flett configured his drive like that for a specific purpose.
The big gear keeps the two cranks in phase but its primary function in life is the speed reduction directly to a prop.
How or why would an engine designer do it that way when a clutch and gearbox is required .
You could put the clutch on the big gear , but then the gearbox primary shaft runs thru the cranks.
Or to get around that you could have the crank and big drive gears centers inline , with the output shaft stacked directly below , but then the cylinders become spaced well apart and the rocking couple is huge.
Then as you would say KISS , have the cylinders as close together as the components allow , and with small gears on the cranks you could drive the clutch input gear directly behind.
But then you still end up with a big , extra , connecting gear/bearings , churning oil and adding inertia.
I think the 360* Tandem is the best configuration in a Superkart ( or in a bike only if the cranks/cylinders are angled , and the gear cluster stacked underneath ) - unless there is another solution you have , I cant see.

[Frits Overmars]

Well done Frits , but to me Flett configured his drive like that for a specific purpose. The big gear keeps the two cranks in phase but its primary function in life is the speed reduction directly to a prop. How or why would an engine designer do it that way when a clutch and gearbox is required . You could put the clutch on the big gear , but then the gearbox primary shaft runs thru the cranks. Or to get around that you could have the crank and big drive gears centers inline , with the output shaft stacked directly below , but then the cylinders become spaced well apart and the rocking couple is huge. Then as you would say KISS , have the cylinders as close together as the components allow , and with small gears on the cranks you could drive the clutch input gear directly behind. But then you still end up with a big , extra , connecting gear/bearings , churning oil and adding inertia. I think the 360* Tandem is the best configuration in a Superkart ( or in a bike only if the cranks/cylinders are angled , and the gear cluster stacked underneath ) - unless there is another solution you have , I cant see.

I agree with you all the way Wob; I just couldn't resist pulling your leg with those pictures of Neil's tandemtwin

[wobbly]

You forgot Frits ( so did I for a moment ) that I cant feel my leg being pulled.

[Andreas Nilsson]

I am currently building a KTM 300 TPI for supermoto and trying to get my head around the ignition curves. The older carbed bikes had a very mellow timing with 15deg max advance(Blue+ýellow), so when tuning I tried the red curve with 22deg max advance, worked really well. The New TPI bikes got TPS so i guess they found room to add more advance in the 3000-6000RPM range.(green+darkgreen) What i find strange is however that the new TPI ignition curve pull out very little advance. The classic theory would be to decrease advance and aim for around 15 deg @ max power RPM and furher decrease the advance after that.

Any good explanation why this igition cuvre looks like it does? After my first dyno runs i notice the engine goes notably flat right after the 7800RPM peak power. Is it perhaps a way to discourage overrevving ?

[lohring]

Try this:


Lohring Miller

[Frits Overmars]

Try this:

Lohring Miller

Got it now. Thanks Lohring

[wobbly]

Two reasons I can imagine.
First is that as you pull out advance the pipe runs hotter , thus giving more overev power - this is not what the factory want happening, the engine is already unreliable under warranty.
Second , if the thing did naturally want to overev with a hot pipe scenario , they would then have to add more fuel to keep the egt down.
Maybe the single per side TPI injector , is not capable of actually flowing sufficient fuel at those stratospheric 300cc rpms , so adding fuel isnt an option.
Adding an extra pair of injectors , as in the Mk2 TPI , would solve that issue - but KTM would know already they cant patent that , as some bunch of bastards from down under
have done it already.

[Brett S]

I think you should spark up the 2 stroke whipper snipper before the bike, that's a fire hazard..

The most advanced twostroke in the world, well, perhaps just the most advanced TPI in the world. Anyway its been sitting outside under a cover for almost a year, bad me.
Finaly got excited about it enough today to sort the Ignitech out, found spark. Turned the LINK ecu off and fired it up using plastic bottle injection. Loud, but it runs, yay. Tomorrow get the LINK ecu working.

[Flettner]

I think you should spark up the 2 stroke whipper snipper before the bike, that's a fire hazard..

Dont you you just use a match to clear the long grass?

Actually just been clearing around the bike, got stung by some jolly wasps. Barstards got what was coming to them, their nest is somewhat flat now.

[Peter1962]

Two reasons I can imagine.
First is that as you pull out advance the pipe runs hotter , thus giving more overev power - this is not what the factory want happening, the engine is already unreliable under warranty.
Second , if the thing did naturally want to overev with a hot pipe scenario , they would then have to add more fuel to keep the egt down.
Maybe the single per side TPI injector , is not capable of actually flowing sufficient fuel at those stratospheric 300cc rpms , so adding fuel isnt an option.
Adding an extra pair of injectors , as in the Mk2 TPI , would solve that issue - but KTM would know already they cant patent that , as some bunch of bastards from down under
have done it already.

Beaten at their own game ?

[SwePatrick]

Well, I was general in my statement. anyway i agree that honing a dlc surface will be a problem. Making a start and stop on the thickness of a DLC coating will be a challenge in itself regardless of the material, and nothing I would choose to try. however, to cut off eg 0.5mm from a dlc coated part, I can not say is impossible as the material behind will give way.

I would say it´s far more better process to hone rod to correct spec including coating, BEFORE coating it.
And aslo include the needlebearing cages and the wristpins.

[Frits Overmars]

I would say it´s far more better process to hone rod to correct spec including coating, BEFORE coating it.

Quite right Patrick. DLC-coating an object that is not very smooth already, will in fact create a diamond file.

[Muhr]

I would say it´s far more better process to hone rod to correct spec including coating, BEFORE coating it.
And aslo include the needlebearing cages and the wristpins.

Hi Patrick sorry if you feel I have suggested any execution.
To my knowledge, I have neither expressed which method is preferred nor that one should process bearing surfaces after dlc coating.
Dlc coating is in many cases thinner than the tolerance range of a roller bearing assembly, which means that you probably you can find a pin and a rod that you can run without machining, however, a very good Ra is needed. In the picture with tm rod you can see a pankl piston pin that has lost most of its coating due to slightly lower surface finish (that is at least my analysis). all parts have been used one World Cup round.