ESE's works engine tuner

[ken seeber]

My suspicions lean toward faulty heat treatment leaving the small end brittle.

Agreed. And for the actual eye of the rod to split as well is unusual. I've seen a few kart rods broken, but almost always thru the shank, not the eyes.

[Flettner]

Agreed. And for the actual eye of the rod to split as well is unusual. I've seen a few kart rods broken, but almost always thru the shank, not the eyes.

+1 , not tempered properly, or not masked properly in hardening.

[Grumph]

Agreed. And for the actual eye of the rod to split as well is unusual. I've seen a few kart rods broken, but almost always thru the shank, not the eyes.

Yeah, I've broken as much or more stuff than most - but never seen a rod break out the small end.
Since a good friend got a magnaflux setup, I've broken a lot less, LOL

[husaberg]

Hello.

Squish clearance 1.2mm, with combustion chamber designed by me. Around 12:1 compression
Cheers

For squish to be effective it needs to be up close and personal
They need to just kiss and end up just short of making intimate contact
1.2mm clearance is not squish, its barely holding hands.

[jamathi]

When you say you had trouble with the reed valve, do you mean you had trouble with it repeating on the dyno? Or trouble trying to get power out of it?

Of course the reed valve is a big obstruction for inlet flow.....
While a rotary valve is not!
And when dyno testing the reeds keep breaking, costs you half of your time.....
The rubber detaches itself from the reed case after some time.
I really HATED it!!!!

[tjbw]

Here's a broken small end, with fatigue crack:

http://products.asminternational.org...rd=729&search=

No special equipment required to see the fatigue surface.

[speedpro]

I looked at that broken motor and "my" immediate thought was that it had the tits revved off it, speaking from experience with such disasters. The broken little end need not have been due to any sort of flaw. I've smashed a 4-stroke rod in such a way on a roller crank type engine and I've completely smashed the little end on one 2-stroke, not to mention giving the rod 2 90-degree bends and a twist, and broken chunks off a couple of other little ends.

[TZ350]

... the small end top part of the rod blown up in the first miles of running in (claimed by the owner). He also says that there wasn't any strange noise on the engine before the "tic-tack and blow".

After all your work, I am sorry to see the rod failure. I had something similar with a cast piston which fell apart when it was revved well past its normal range. The only warning was a little tinkle in the expansion chamber which I assume was bits of piston, I got the clutch in just before the engine beat itself to death.

The end of my rod was missing too and the pin was split lengthwise into several bits, all the bottom of the piston below the rings was missing and funnily enough the piston crown was still in the bore and from the top it looked as if nothing was wrong.

... an engine, that had several people making stuff for it here in Portugal,

I am very interested in the head shape, it is hard to tell but are the sides straight bath tub like or curved like a toroidal? I ask because one I made recently looks similar and I would be interested in your impressions about yours.

[RomeuPT]

Thanks all of you for replys.

After all your work, I am sorry to see the rod failure. I had something similar with a cast piston which fell apart when it was revved well past its normal range. The only warning was a little tinkle in the expansion chamber which I assume was bits of piston, I got the clutch in just before the engine beat itself to death.

The end of my rod was missing too and the pin was split lengthwise into several bits, all the bottom of the piston below the rings was missing and funnily enough the piston crown was still in the bore and from the top it looked as if nothing was wrong.



I am very interested in the head shape, it is hard to tell but are the sides straight bath tub like or curved like a toroidal? I ask because one I made recently looks similar and I would be interested in your impressions about yours.

Head shape has no logic, its just the athena piston is 66 and many dt users just fit it with a standard head (56mm) so the flat part is to make sure even when the user is stupid it will not be a big problem.

Cheers

[breezy]

Transfer ducts.

Many transfer ducts with small differences were tried.
We found more power by enlarging the A-port in the direction of the exhaust.
Only the lower half, but it was important to give the A-duct an inclination away from the exhaust!
The ducts were very conical, the smallest point being the port.
In and outside walls of the ducts had a constant radius from top to bottom.
The flow remained attached to the inside radius and so cooled the piston and eliminated detonation.
Flow bench testing and the Jante type testing proved useless for power improvement.
Giving the rear side of the B-duct an inclination versus the middle of the cylinder gave a big improvemet

Jan, how were you able to know when the flow was attaching or not to the transfer walls?

[marsheng]

Do you remember the difference between both of the A-port variations from the picture? Which was better, version A or version B?
Attachment 330106

Have I missed the answer to this ?

Also what were the timings of the ports and roof angles.

Thanks Wallace.

[Frits Overmars]

Have I missed the answer to this ?

Yes you have.

Version A was the best.

Also what were the timings of the ports and roof angles.

The drawing shown by Jan in post #25655 showed an elder type RSW cylinder. Here are the RSA values.
A-ports timing 130°, roof angle 25°
B-ports timing 132°, roof angle 10°
C-port timing 132°, roof angle 50°

[Frits Overmars]

Some wishful thinking:


And some miraculous saving:
https://www.facebook.com/MotoGP/vide...5598630555769/

[Peter1962]

Some wishful thinking:

That is a nice concept of a KTM 2 stroke roadbike, based on the 300 cc enduro engine ? Probably the 2018 version with injection in the transfers ?

[jfn2]

Frits:
It looks like the guy fell asleep! Mesmerized maybe?