Topic: 69mm pistons?

[turboguzzi]

Looking at Satanic Mechanic's site, I've seen he mentions 67.5mm and 70mm big bore kits.

Does anybody ever cam across 68mm or 69mm pistons?

Need them for my new secret project, all will be revealed in time.... 

TG

[mec]

eventually you will find page 95 and 100 interesting for you?
http://www.woessner-kolben.de/sites/default/files/Motorcycle_Pistons_2009.pdf

mec

[turboguzzi]

eventually you will find page 95 and 100 interesting for you?
http://www.woessner-kolben.de/sites/default/files/Motorcycle_Pistons_2009.pdf

mec

Thanks Mec,

Yes, of course that making custom ones is always an option, just trying to see if there's something on the shelf already with 69mm / 15mm pin.

Asso and Pistal in italy also do cutom pistons but it was great to see that Woessner have this very large ring choice, will sure help in other projects.

Cheers

TG

How's the guzzi?

any idea of Woessners proces for a small batch? 

[754]

 Cosworth may do a custom order or short run.. I think they are experienced...

[kos]

Stay here in "merica. JE Pistons will make any piston you want, but be sure they can provide rings in bore size you are wanting.  Make sure you can draw out what you want and explain in detail the design you are wanting with measurements!  You will need some experience in working with engineers and people that ask a lot of questions.

KOS

[Kurlon]

What pin height do you need, and what size valves/combustion chamber are you going for?  Akunar has a bunch of 69mm bore / 15mm wrist pin pistons.

http://www.akunar.com

[turboguzzi]

Believe it or not, am currently using akunar pistons on my racer.

Never felt like recommending them because:

1. I had received very bad treatment from customer service. 

2.The piston design is very modern, but the quality is only so-so. Piston pins had huge internal machining marks, didn t even used them, pistons had pin oil holes undrilled, etc.

On the other hand, I am on my third race on them and during this winter's rebuilt they looked OK.

But still, they could be an option, at least for a first test.   

[mick7504]

Hey TG
Don't know if you saw this on Axl's site.
Mick
http://www.satanicmechanic.de/board/viewtopic.php?t=355&postdays=0&postorder=asc&start=0&sid=cdbe05a5eb450d57f68dd07eb056009e

[mec]

How's the guzzi?

hello,

everything is fine. I am hoping to have the first roll out end of april, beginning of may. there is a 50:50 chance to compete at the GTF race at pannoniaring 1st of may.

mec

[turboguzzi]

Hey TG
Don't know if you saw this on Axl's site.
Mick
http://www.satanicmechanic.de/board/viewtopic.php?t=355&postdays=0&postorder=asc&start=0&sid=cdbe05a5eb450d57f68dd07eb056009e

Thanks for the link Mick, surely interesting. soon you'll see why.

Checked akunar, deck height waaaayyyy too low. the 69mm one's got 20mm, I need 25....

Had the same problem with the 57mm piston  I bought from them for the 500, had to mill tons off the block and head but not 5mm!

Those are after all big bore kit pistons for much more modern stuff and nowadays pistons are extremely short

Leaving custom pistons for last really, we'll see.

Mec, wow! you are quick! So will you bring the Guzzi to spa? What about some updates on it? I'm sure nobody will tell Sam or Mlinder to move out a short racing guzzi post  

Some sun here at last, after having a very rainy easter closed in the garage finishing off my bike, took my girl for a bicycle ride to a nearby middle ages church estate. Don't forget your ladies guys..... specially the ones that can stand our reclusive activities!

Happy Easter to ya all.

TG

[Kurlon]

Has anyone dug around to see if there is a direct swap rod option that is say... 5mm longer?  Get a little bit better rod ratio, AND be able to run more modern pistons in one move?

On the Akunars they are certainly a cheaply made unit, but so far they've held up pretty well for us in race single cylinder motors.

[turboguzzi]

Has anyone dug around to see if there is a direct swap rod option that is say... 5mm longer?  Get a little bit better rod ratio, AND be able to run more modern pistons in one move?

On the Akunars they are certainly a cheaply made unit, but so far they've held up pretty well for us in race single cylinder motors.

Kurlon, in what engine/bike are you running these pistons? If its a single then its quite interesting.... There's a guy here that is trying to start a small series around CB125's, a bit like CB160 racing in the US.

Dont know what engine do you want to fit longer rods to but member howell discovered that GSXR1000 rods are a straight fit on the 500/550 crank and longer by a few mm's. 

[Kurlon]

http://www.x386.net/TTR/media/unsorted/HPIM0357.JPG
http://www.x386.net/TTR/media/fishtail/_K5C5820s.jpg
http://www.x386.net/TTR/media/06Rebuild/06-15Bike/HPIM0409a.jpg

The rods question was aimed at Truboguzzi, as he noted the pin heights on the Akunar units was too low.

[fastbroshi]

  I believe GSXR rods of some sort my be an excellent fit.  Howell used them in his racer, don't think he gave specs though.  Maybe he'll chime in here.  On a side note,  I got to talking with my neighbor who used to drag race his 550 and he told me the stock rods never gave him any problems and all he did was have them shot peened.  Said he used to rev it to 13k on the strip.