[2 Stroke] How plug up a 2-stroke wristpin?

Ciao a tutti,
I have a little question about a Cagiva Mito barrel with large booster; how plug up the wrsitpin, avoiding the "short circuit" between exhaust and transfer?
It's a 16 mm pin, can't fit an Aprilia GP pin!
I'm thinking to put some kneadatite into the pin ID..any suggestions?
Thanks

Filandro a écrit:

Ciao a tutti,
I have a little question about a Cagiva Mito barrel with large booster; how plug up the wrsitpin, avoiding the "short circuit" between exhaust and transfer?
It's a 16 mm pin, can't fit an Aprilia GP pin!
I'm thinking to put some kneadatite into the pin ID..any suggestions?
Thanks

Aprilia wristpins were made by Pankl.
It was done by welding.
Every different solution we tried was a failure.
Maybe they will make some for you too!

Hi Jan, thanks !

Pit Lane désormais lieu de rencontre international !
On s'échange des renseignements techniques de pays à pays via P.L.
Bravo Marc ! Belle réussite (sans flagornerie)

Kentai, vous have to thank Jan and Frits, not me...

Filandro a écrit:

Hi Jan, thanks !

Dont go to Pankle, they rip you. Go to : THOMAS MüLLER LASERTECHNIK in Neukichen-Vluyn in Germany, the real wizard in the highest quality of laser welding AND affordable.

Ciao

Hi Bob, thanks for your answer!

Hi Guys,

I do have a question regarding welding of wrist pin..

Is piston pin cooled by it's construction (as pipe, not rod)?
If we weld ends, is there any negative side effect, by wrist pin accumulating heat more than predicted and thus expanding more, having negative effect on central (needle) bearing and "bearings" (position) in piston?

Or, opposite, it is better to weld it, for same reason?

Put aside benefits of closing passage.

Thanks,
T.

Hi guys,

Mabe this solution made with PEEK.
What do you think?

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Did you test it? What were the results? And how much does it weigh?

Hello Frits,
The weight of this PEEK insert : 5,62 gr.
The welded 15mm pin from Pankl : 35,28 gr.
My pin with this insert : 37,00 gr.
I think with an other design, i can gain 1 gr.
I only have to find a solution for assembling the 2 parts together.

Results not yet, a bit later for sure.
What are the benefits do you think?

Hello Frits,

Some small modifications in shape brings less weight.

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Hoping the pluged pin brings me a gain in performance, what do you think about ?

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Thank you

Vortex a écrit:

Hoping the pluged pin brings me a gain in performance, what do you think about ?

Jan Thiel already established that the plugs improve performance. But I think you need to concentrate on something else:

Vortex a écrit:

I only have to find a solution for assembling the 2 parts together.

Hi,
I think the best polymer is polysulfone molded in situ , no need to be attached, hold very high temps without structural dilatations, but there is a very expensive material.

Cheers.

Vortex a écrit:

Hello Frits,
The weight of this PEEK insert : 5,62 gr.
The welded 15mm pin from Pankl : 35,28 gr.
My pin with this insert : 37,00 gr.
I think with an other design, i can gain 1 gr.
I only have to find a solution for assembling the 2 parts together.

Results not yet, a bit later for sure.
What are the benefits do you think?

There are two methods I have thought of using:
1. Exactly what you have done but add a thread to the pieces and use a locking agent to secure (maybe a bit hard to disassemble though this might not be a problem if they survive
2. Mold the plug within the pin - either by pouring a liquid chemical which later hardens or make the material extrudible by heat or other means and push it into the pin, flaring the ends of the plug in a die -machined to the required shape after the process.
I would like to hear if anyone knows a suitable liquid chemical that can be used or how to make the material extrudible.

Those polymers are thermical hardening behaviour, no more melting after chemically react.
To remove them , there is only one possibility >burning.

Use Vespel. Very expensive but it works. Machine the plugs to snap into the circlips.

Yes, i think so.
Thank you Howard.

Dear Mr. Frits,
One other pic, TT to high or what is here going on?

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Any advise?
Where to buy your software?

Thank you

Howard Gifford a écrit:

Use Vespel. Very expensive but it works. Machine the plugs to snap into the circlips.

You win the refrigerator, Howard   .
We don't use Vespel, but something quite similar (and even a little more expensive   ).

Vortex a écrit:

Dear Mr. Frits, One other pic, TT to high or what is here going on?
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What am I looking at? At first glance I saw a cylinder with three transfer ports and zero exhaust ports.
On second thought I think it is a cylinder with only two transfer ports flanking a single, too-narrow, too-low exhaust port; not a racing cylinder at all.

Citation :

Where to buy your software?

You can't; it never was for sale. I gave it away; I only took money for the hardware that went with it.
But I stopped adapting it to ever newer and better(??) Microsoft Operating Systems.
When I started writing my programs, I used Algol (ancient Greek for computers). Those programs would not even run on home computers, because these did not yet exist. Later, when I got my own PC, I had to rewrite everything for the MSDOS operating system. And when that was succeeded by Windows95/98 I had the same pleasure again.
The sad thing about it is that this repeated labour did not contribute a thing to the functionality of the programs; it only served to keep them alive under ever more Microsoft-belches.

The programs in their present form run under all Microsoft operating systems from DOS 6.2 to Windows 98SE. Depending on the graphics card in a particular computer they may also function with Windows 2000 and XP. Under Vista and Windows 7 they can be used via an emulator. But the recent Microsoft operating systems are so preoccupied with virus control that real-time communication between my electronic equipment and the computer suffers. Of course there is a solution: rewrite all programs and have new measuring equipment built, at appreciable financial consequences. And then, when everything functions again, Microsoft will introduce something even newer, even better, and I can start all over again. I am not young enough anymore to waste my time with such nonsense.

Hi All

On our new 250cc single Superkart motor, before going to large amounts of trouble in manufacturing a permenant method of plugging the piston pin and closing the cavity between the end of the pin and the edge of the piston, we used this simple plug arrangement to test. The pin is 18mm O/D and 13mm I/D. the head of the allen bolt sits into a counter-bore so it is flush with the plug.

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The assembly weighs less than 15 grams and we were able to machine the interior of our prototype pistons so that the complete piston assemblies used for the test (with the plug) and for the control (without the plug) were identical weights.

You can see that the assembly clamps either side of the right-hand circlip, therefore can't move side-to-side in the piston. The wider step on the left-hand side means that it doesn't clamp on the left-hand circlip which might cause unwanted stress.

The bolt is an M4 and we used medium strength Loctite to retain it. It stayed in place admirably for perhaps 20 minutes total running including about 10 dyno runs both single top gear runs and through the gear runs, allowing the engine to run out of overrev at the end of each run.

I was able to remove the assembly quite easily straight after the last run (it was still quite hot), by digging the point of the pointed tool that I usually use for circlip fitting/removal into the side of the threaded portion via the pin installation slot.

I wouldn't recommend it as a permanent solution, but fine for testing. We learnt everything we needed to know and will proceed accordingly.

Best Regards

Ian 

hello Ian , i'm having problem with carbon reeds ( cr250 ), , Vf3 and stock cages with 4 or 6 windows in KitA 125 honda engine ( not production cases )

have you any special reeds to get high rpm for me or any tip welcome as they are to light on tension to work correctly ...

thanks

Seb

been reading on the RD/RZ forum, and aparently Tony Doukas from TDR-racing (http://www.tdrrz.com/)  makes them from titanium.

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midle of the page in his 1. answer.

EDIT : apparently it was something he did some time ago to increase crankcase compression, not to avoid interference between aux and transfer.

Ian Harrison a écrit:

Hi All

On our new 250cc single Superkart motor, before going to large amounts of trouble in manufacturing a permenant method of plugging the piston pin and closing the cavity between the end of the pin and the edge of the piston, we used this simple plug arrangement to test. The pin is 18mm O/D and 13mm I/D. the head of the allen bolt sits into a counter-bore so it is flush with the plug.

[Vous devez être inscrit et connecté pour voir cette image]

The assembly weighs less than 15 grams and we were able to machine the interior of our prototype pistons so that the complete piston assemblies used for the test (with the plug) and for the control (without the plug) were identical weights.

You can see that the assembly clamps either side of the right-hand circlip, therefore can't move side-to-side in the piston. The wider step on the left-hand side means that it doesn't clamp on the left-hand circlip which might cause unwanted stress.

The bolt is an M4 and we used medium strength Loctite to retain it. It stayed in place admirably for perhaps 20 minutes total running including about 10 dyno runs both single top gear runs and through the gear runs, allowing the engine to run out of overrev at the end of each run.

I was able to remove the assembly quite easily straight after the last run (it was still quite hot), by digging the point of the pointed tool that I usually use for circlip fitting/removal into the side of the threaded portion via the pin installation slot.

I wouldn't recommend it as a permanent solution, but fine for testing. We learnt everything we needed to know and will proceed accordingly.

Best Regards

Ian 

Hi Ian,

What did you see on the dyno with the pluged pin?

THX

Absolutely no difference with or without  

Best Regards,

Ian