Topic: cb750 to 900cc -- I need one 67mm big bore Henry Abe piston

[fang]

I need one of these:

(Thanks SatanicMechanic for the picture.)  This is a Henry Abe, 67mm, 900cc big bore, "slipper-style" piston with large valve cutouts for a SOHC CB750.

I have a 67mm Henry Abe kit installed in my cb750, complete with big sleeves and bored out crankcase....  But I broke a piston.  The oil ring pinched when installing them, cracking the metal between the piston rings.  DANG!

If any of you have one you can spare, I need one, and I can promise it will go to good use.

Thanks in advance,
-Fang

[Big Jay]

Probably going to have to buy a second kit. At least you will have a spare ring set and head gasket.

Jay

[fang]

Maybe so, but I need to ask everywhere I can!
Besides, I already have a spare head gasket and set of rings.....  =)  I know a guy who is looking for a set of replacement rings for one of these.  Maybe we could try to go in together for a set.
-steve

[fang]

Saturday morning visibility bump.

“When kids hit 1 year old, it's like hanging out with a miniature drunk. You have to hold onto them. They bump into things. They laugh and cry. They urinate. They vomit.'”

If anyone has one of these pistons I will cry... Just like a little girl.
-fang

[moham]

All I gotta say is "real nervous pegs with a crazy crease"...man, the fang, that's great shyte.

[fang]

I appreciate a man who knows his shyt.
-fang

[scunny]

I might get a chance tomorrow to look at a set of these plus sleeves, can't remember off hand if they are new or used but will let you know, seem to remember he wanted $900 NZ wich seemed a bit pricey to me.

[fang]

I have no idea what $900 NZ = in $USD, but a whole Henry Abe kit which includes new pistons, rings, pins, clips and a head gasket tend to sell for about $300 +/- $50.  I have bought two or three for about $200. 

I might have a lead on 8 of these pistons, used and possibly damaged for about $20 + shipping.

-fang

[fang]

Here are two pics of the damaged piston.  Click for a great big, fat, macro view.





Anyone have any good ideas?  Anyone?  Anyone?
peace and grease,
-fang

[Terry in Australia]

Here are two pics of the damaged piston.  Click for a great big, fat, macro view.





Anyone have any good ideas?  Anyone?  Anyone?
peace and grease,
-fang

Why not get it repaired? I bought my 1060cc MTC pistons from a guy in the US and he sent them to Sean Condon to send to me, and Sean noticed that a chunk had been knocked out when the PO had somehow tapped out the wrist pin without first removing the circlip? Oooooer!

The seller asked me to send it back to him, and even though I had little confidence that he'd fix it properly I did, and I must say, he did a brilliant job of welding/machining that piston, he even managed to machine a new circlip slot in it, it just looks perfect. Do you know anyone with a tig welder and a lathe? Cheers, Terry.

[fang]

That is a good idea -- one that I had not really seriously considered.

So the call is out!

Does anyone out there know of a machinist with the Mad Skillz to repair a piston?  If so, please send me their contact info!

-fang 

[Jerry Rxman Griffin aka MuthaF'er]

Hey Fang,

Why not contact Hastings or Total Seal and see if they can repair the piston or perhaps know someone that can? I sent my 73.75mm pistons to Total Seal to be cut for 3 piece rings so they do provide some services. If you should happen to send them the piston and rings how about asking if they can match up the rings so we can include that info in our data base. I'm eventually going to have to find 3 piece rings for my set.

Jerry

[fang]

I did some trolling over at our brother forum, the SOHC Chopperz Forum.  I used to spend a lot of time over there.  They are good guys.  Anyway, I got two fair leads on some 67 Henry Abe pistons.  That was a huge encouragement.  I hope one of them works out.

Jerry,
I agree about finding some 3-piece rings.  My first two set of Henry Abe pistons came with the 3-piece oil rings. The 3rd and 4th did not.  (The 4th set was a recent purchase off eBay from that guy at Rusty Riders.  He's been selling sets of H-A 67mm rings and head gaskets w/o sleeves or pistons.  I just got the rings and gasket; he didn't have anything else for sale.  My other previous kits all included everything: pistons, rings, clips, pins, sleeves, and a head gasket.  Two of the kits included a base gasket.)

I can't help but wonder about the "universality" of modern 3-piece oil rings.  I mean, there are a number of modern and old bikes out there with stock 67mm pistons.  If they have oil rings at all (ie forget all the 2-strokes), then it seems there is a good chance they might fit. 

• The new Honda CBR600 has stock 67mm pistons
• The new Yamaha R6 and Kawasaki ZX6R also have 67mm pistons
• A number of the single-cylinder Honda, Suzuki, etc 4-stroke dirt bikes and ATVs either have 67mm bores, or have bore-up kits to bring them up to 67mm.  This is true for the 1980's - to present.
• The Kawasaki 900cc z bikes (Z900, LTD900) -- their 1.00mm (1st oversize) pistons are/were 67mm
• The old 1980's DOHC CB900s had 64.5mm bore, so the over-bore might fit
• The 973cc over bore for the CB1000s has 67mm
• The old '80-'85 Kawasaki GPZ 750s (both turbo and N/A) had 66mm pistons ,so 1st over is 67mm.
• I am pretty sure the old '80-'85 Kawasaki GPZ 750s non-turbo had 15mm wrist pins (like our CB750's).  Plus they were 8-valve motors.  They might be an option for a direct drop-in big-bore piston.  There is a 69mm Wiseco kit for this bike -- if it fits, it would be in the ball park of 942cc in a CB750.  However, I don't know anything about the GPZ piston skirt legnth, nor the crown's shape, height, volume, etc.   It would be very exciting if this is a real option as a big-bore drop-in piston.  Hmm I really need to look into this.

...

Back to 3-piece oil rings... I guess the first step to finding compatibility is to get some measurements of the H-A pistons' oil ring channel.  Seems that depth and width is what we need.  Then we can call a few people like Wiseco to see what is out there.  I have two virgin sets of H-A, 3-piece oil rings sitting on my workbench right now.  Two sets, as in two piston's worth.  That might help.   They are sitting next to a full set of single-piece oil rings.  Maybe the way to do this is to measure the big, fat single rings for dimensions.  I don't know.

LOL!  I mean, seriously:  There are only a handful of people in the world who even know what H-A pistons are for the CB750.  Fewer own them, and even fewer care about 3-piece oil rings.  We are a minority's minority.   Nevertheless, I am amazed at how many dudes have these kits stashed away.  The world is a crazy place.

Anyway, its late.  Good night.

peace and grease.
-steve

[Terry in Australia]

Hey guys, while we're talking piston rings, I need some compression rings for my 72mm 1060cc MTC pistons.

I found that my Suzuki GS1100 three piece oil rings fit perfectly, but at 1.5mm, the compression ring slots are too wide on my old MTC pistons for the Suzuki compression rings ?

Does anyone know where I can find some 1.5mm thick 72mm compression rings? Cheers, Terry.

[fang]

I spent hours thumbing through the Wiseco piston catalogs.  They are searchable as .PDFs
HERE is a link to the complete 2008 V-Twin/Metric piston catalog.
HERE is a the Street one.

Look for something with the correct diameter.  Use the search feature for "72.00."  When you find a couple, then call Wiseco asking for details on those sets of rings.  There probably is a better way to do this, but that is what I was doing last night (minus the calling).

Happy hunting!

... What do you think about the GPZ 750 pistons?  I am excited about the idea.

-steve

[Terry in Australia]

I spent hours thumbing through the Wiseco piston catalogs.  They are searchable as .PDFs
HERE is a link to the complete 2008 V-Twin/Metric piston catalog.
HERE is a the Street one.

Look for something with the correct diameter.  Use the search feature for "72.00."  When you find a couple, then call Wiseco asking for details on those sets of rings.  There probably is a better way to do this, but that is what I was doing last night (minus the calling).

Happy hunting!

... What do you think about the GPZ 750 pistons?  I am excited about the idea.

-steve

Thanks Steve, I'll check the links when I get home. Re: the GPZ pistons, if the stock size is 66mm, then first oversize will be 66.25, then 66.50, 66.75, and finally, 67.00 will be FOURTH oversize, if you can find them.

Most important is the height from the centre of the wrist pin to the crown, for example, I bought a NOS 65mm "Action Fours" big bore kit for a Kawasaki KZ650 (718 kit) as it has 15mm wrist pins and of course, 65mm for a CB750 is 836cc, but the crowns are too high, and the valve reliefs are in the wrong position for our engines with the canted valve arrangement. Cheers, Terry.

[fang]

right on, Terry. I'm with you 110%.
I can still hope.
 

peace and grease.
-steve

[Big Jay]

Hey guys, while we're talking piston rings, I need some compression rings for my 72mm 1060cc MTC pistons.

I found that my Suzuki GS1100 three piece oil rings fit perfectly, but at 1.5mm, the compression ring slots are too wide on my old MTC pistons for the Suzuki compression rings ?

Does anyone know where I can find some 1.5mm thick 72mm compression rings? Cheers, Terry.

Terry;
I think that was the original Honda GL1000 Goldwing.

Jay

[bryanj]

Terry and Jay
GL1000 75-79

Cylinder I.D. 72 to 72.015

Ring groove width (top & second) 1.5-1.52---clearance 0.02 to 0.045
Ring groove width (oil ring) 2.805-2.82

piston pin 17 dia

ring gaps top & second 0.25 to 0.4 oil 0.2 to 0.9


Hope that helps

All Data from Genuine Honda Manual

[Terry in Australia]

Hey thanks guys, you blokes are brilliant! Now I'm gonna go find me some rings............. 

[bryanj]

No problem Terry, I have tones of crap, sorry information here its just finding it that aint easy!!!

[fang]

There has been a parallel to this discussion going over at the Satanic Mechanic CB750 forum with some good pictures.  HERE.

I bought a set of used Kawasaki GPZ 750 pistons of eBay today.  LINK.  Worked out a deal with the seller and he only is mailing me the pistons without the cylinder block to save shipping.  I also am going out of town tomorrow for about three weeks.  When I get back I will take a good look at them and post some comparison pictures of them with my Henry Abe pistons.  That might be as late as early March.

peace and grease.
-fang

[Soos]

Hey... in case you missed my PM....



In this http://www.satanicmechanic.de/board/viewtopic.php?t=355 thread you posted you would offer the GPZ750 pistons for the cost of shipping....

Do you have those still, and is the offer still good?


I'm tempted to buy a set to test out(measure and machine) but am afraid of scrapping a set of pistons I shell out a good chunk o change for.
Your GPZ750 pistons you posted for the cost of shipping sounds like a perfect candidate for this type of test IMO...

PM me if you get a chance.

l8r

[fang]

Sure.  The offer is still good.  Check your PMs.
-steve

[Terry in Australia]

Hey what a great thread, I have a NOS 65mm "Action Fours" big bore kit for a KZ650 Kawasaki (718cc) that I bought on EBay years ago to use in a CB750 engine, but like Fang, discovered that the domes were a tad high for my "K" bikes, but didn't think about my F2?

I've currently got a K6 top end on the F2 but I'd much rather add to the original F2's performance with an 836cc kit that I've had sitting in a box for the last 5 or 6 years, ha ha! Thanks Fang, you've got me thinking! Oooher, but then again, I've got my own boring bar, so maybe I'll go buy a set of GPZ750 pistons! Anyone need a NOS 836cc kit for their F2? Cheers, Terry.