Topic: My piston project(s).

[traveler]

Work that head.....the power you are getting from this will go up 10-12% I estimate.

~Joe

Are you estimating according to pure displacement increases? Or taking into consideration displacement and compression? Hate to say it, but I know you're not taking into consideration the Surface Turbulence, as I can guarantee you have no experience with it. This will be the main source of increased efficiency and power.

Really?  I don't remember meeting you....

~Joe

[Pinhead]

Which is exactly my point.

[traveler]

mind reading must be a rare item these days

[Soos]

Middle row
std 550, cb750 auto piston W/ "Gentleman's Express" & 0.330 lift valve pockets, std 750 piston with same mods, std cb650 piston

Bottom row
cb650 piston modified to "Gentleman's Express" specs W/ clearance for 550 running a 650 cam, next as before but w/+2mm to the diameter where I started the 15 deg cut, third +4mm, fourth +6mm.

Man, where was this stuff a year ago?? Good work, dude. I may have to start another 550 just to get in on some of those...

In my wildest dreams, why?

You get there, I'll whip you up a set.
I could do it before(to an extent), but now am way better tooled up to do piston mods on both the lathe and mill.



How are those 60mm pistons holding up anyway?
Running well I hope!!




l8r

[V4 Lover]

So what kind of final HP outputs are you looking at here? Either with Pinhead's or your 763cc?

[Kemp]

Soos, did you finalize the KZ650 pistons in the CB650 cylinders? Still interested in whether this is a viable option in the 550/650 hybrid build. Looking for a lower cost yet reasonable displacement CB550/650 conversion much like paulages but without the high machining costs associated with larger liners. The idea would be to use 550 cases as paul did as well as 650 cyl, crank and head (ported, flowed, Megacycle cam, 750 carbs ). Displacement around 673cc. I guess the main issue would be valve size cut outs and squish/dome machining to make the pistons work. Got a set of KZ650 pistons in front of me and they look very promising.

[Soos]

Soos, did you finalize the KZ650 pistons in the CB650 cylinders? Still interested in whether this is a viable option in the 550/650 hybrid build. Looking for a lower cost yet reasonable displacement CB550/650 conversion much like paulages but without the high machining costs associated with larger liners. The idea would be to use 550 cases as paul did as well as 650 cyl, crank and head (ported, flowed, Megacycle cam, 750 carbs ). Displacement around 673cc. I guess the main issue would be valve size cut outs and squish/dome machining to make the pistons work. Got a set of KZ650 pistons in front of me and they look very promising.

Nearly.
I do have a set of 62mm pistons ready to go(rings and all!)
They were THE MOST work of any piston I have mod'ed to date though.
The dome, simple.
The valve releifs, simple.

Figuring out how to hold the pistons while cutting all the ring lands wider WITHOUT making new piston holding fixtures..... A PITA!
However, after a few discussions with a few wily old machinists, I got something going(not my favorite but it works well)


And yes 62mm pistons are as big as you can get using cb650 liners(and not resleeving)
If you REALLY need them, I would be willing to trade the 62mm pistons+rings of mine for your $$ and your pistons.
I have a set of bored(not honed yet) cylinders that can go for the right $$ as well.





I'll post letting everyone know when I have a bit of time to do more piston mods for everyone.
Right now, a family member has moved into my house, I am still on vacation(and work wants me to come back early), as well I will be in OT mode at work for the first 2-3 weeks back.
It's nice being the big fish in the little pond at work sometimes.












l8r

[Kemp]

Great news Soos! Question; why change the ring grove in the KZ650 pistons? Yes, I would be interested in a swap plus $$$. Probably interested in the barrel swap also although the shipping to Toronto Canada might be prohibitive on that item??

Kemp

[Soos]

The ring groove widening was due to the prohibitive $$ for KZ650 rings.
The CB750 +1mm rings were $50 for 4 sets.
Compared to $75 PER set. A full set for 4 pistons was quoted to me (with tax) at just under $325.00.   

So me being able to adapt to cb750 rings was a massive advantage IMO.



The only thing I think I MIGHT do past what has been done is add some oil weep holes.
All the cb750/550/650 (overbore and stockers) have more oil drain holes than these KZ650 pistons do.(in/below the 3rd ring groove)

But I dunno, the KZ has 5 in each side in the ring land area.
the CB pistons have had 4 in each side of the ring land, with 3 holes(offset from the set of 4 in the ring land) on the bevel just below the 3rd ring.

But also the KZ pistons have more of a wrist pin offset as well.
Perhaps I am worrying about nothing, they were designed well, just slightly different?



And prohibitive as far as $$ for shipping the cylinders....
That depends on how big/deep your pockets are.

Might be cheaper to have yours done locally.
I do have a set bored(not honed yet) if seriously interested though.

Gotta go slave away. Just checking in for a few minutes




l8r

[Kemp]

Hi Soos,
          Piston swap sounds good, what would the cash difference be. That's amazing about the difference in cost between Kawasaki and Honda!
          When you say their is a wrist pin offset that is different from the Honda, what do you mean? How would this affect the engine, would the rod be pulling the pistons down at the wrong angle

[Soos]

Hi Soos,
          Piston swap sounds good, what would the cash difference be. That's amazing about the difference in cost between Kawasaki and Honda!
          When you say their is a wrist pin offset that is different from the Honda, what do you mean? How would this affect the engine, would the rod be pulling the pistons down at the wrong angle

For the piston swap, how about $80(US) + your pistons shipped to me?
It's more than the usual $50 for piston mods, but most piston mods don't need the ring lands widened.

And the wrist pin is 1mm off center.
The cb760/650/550's pistons are all 0.5mm offset.
From what I know the offset allows reduced piston slap.
Would you like to see some photos?




l8r

[Kemp]

That sounds fine, would love to see some pics!! Please send me your mailing address and I'll send the pistons to you. Does this price include rings and wrist pins? As for the pistons I'm sending you would you like the rings and wrist pins with them?
I can send you payment via paypal.

Kemp

[Soos]

That sounds fine, would love to see some pics!! Please send me your mailing address and I'll send the pistons to you. Does this price include rings and wrist pins? As for the pistons I'm sending you would you like the rings and wrist pins with them?
I can send you payment via paypal.

Kemp

 

Yes it includes wrist pins(that came with those pistons), NO that does not cover rings.
The rings are another $50

PM sent



l8r









A little back to the project..... Recently got a cb500 motor to play with.
Now I can test fit cb650 stock pistons cut for 500(and 550?) use.




l8r

[Soos]

Well Kemp, sorry for the wait, but here is your pics of the pistons.


At some point I had dropped one of the pistons, and slightly bent the skirt, but IMO it is runnable.(I would run it in my bike)




l8r

[Kemp]

Hi Soos,
        Pistons look great! What is expected CR using them in the CB650. What rings are you using? I'm a bit confused as I thought there were issues with KZ ring avail and you changed ring land to accommodate Honda rings??

Kemp

[Soos]

You are correct, I have modified the ringlands to accept 1.0mm over cb750 K rings.


Does 2 really nice things (IMO).
1. allows me to not have to clean the friggin ringlands of carbon
2. they use cheaper more common rings.


I have to hone my tester block to accept these 62mm pistons to verify CR.
Something I have been meaning to do for a while now in fact.


This weekend possibly, the hot season is the OT season at work, so personal time is limited at the moment for projects at the moment.

[fastbroshi]

Soos, do you have any notes on the 550 pistons from response  #41 in this thread? 

[Soos]

Soos, do you have any notes on the 550 pistons from response  #41 in this thread? 

Are you talking about the Surface Turbulence ones for Pinhead?
What would you like to know?


l8r

[Soos]

Well,

It's the last day these pistons will viewable in my house(boxing them up soon)
So I thought I would post a before and after pic of KZ650 pistons.

Kemp sent me some trade in pistons for my machined ones, and here they are!

[Kemp]

Nice! They look fast in the raw. Can't wait to start the 697 build.

[Soos]

Glad you finally got them in the mail!


Never again will I do an international shipment thro0ugh USPS.


Never.





l8r

[Flying J]

PMed you. have any more pistons?

[Flying J]

ANybody know where Soos is or what his email is?  Soos.... where are you?

[Soos]

Sorry,



Online time takes third seat to work and family.
And lately work and family have been both very demanding on my time.



The cb750 F pistons you have, are they they ones that the dome starts near the edge of the piston, of the ones with the (2?3?mm) dome rise about 2/3 of the diameter of the piston?
There are 2 varieties.









I am alive people, sorry to any who are waiting on responses to PM's.

responses will be coming soon.




l8r

[Flying J]

they are 77-78 f pistons.