Topic: Hmm. What piston is this? It's a big boy

[rbmgf7]

i was taking apart this engine that i thought to be junk. i was curious as to why 2 tappet covers were blown off. after i took the valve cover off, i noticed aftermarket valve retainers. I'm guessing they're Ti. I also noticed an aftermarket cam chain sprocket and chain. the cam seems stock compared it to another one i had lying around. it could be a special grind from modifiying the stock one. i started to work off the head and noticed, hmm...this is an all copper gasket! i knew only all copper gaskets are used for high compression racing engines. once i removed the head...booya! some aftermarket pistons. i haven't been around the CB750 world long enough to declare what they are so i was hoping for one of the old timers here to spot me. i measured the bore to be roughly 2.652" that's 67.335mm! i'll get some pics once my batteries are done charging.

[rbmgf7]

I think i found what it is. it looks like the wiseco 67mm big bore according to satanicmechanics site

[scondon]

 Found the same thing in a motor that's been sitting in my garage over a year. Been a while so my numbers are probably off a bit, but from what I remember the pistons are 12:1 "910" kit that actually measure to 896cc. Cam is a lumpy, low lift "Kenny Harmon" D grind.

   Axl's satanicmechanic site is top notch for identifying old performance parts

http://www.satanicmechanic.org/


EDIT: you found it

[rbmgf7]

got some photos




Ti retainers? I'm guessing so since it came from a F2. springs look aftermarket too.


couldn't find anything special about the cam.

[scondon]

 Those pistons look familiar, sweet Let's see a pic of that cam if you have one. Stock cams generally have "R" and a number stamped on them.

[rbmgf7]

I found a "K134" and "CWC" stamped on the cam. side by side it looks like a stock cam. i'll crack the cases and see if i can get a better look at the con rods too.

just a thought. can someone appraise these? if an 836 is about $400-$500 then...

[martino1972]

you lucky basterd..
those pistons dont even look old....this is like finding gold...

[rbmgf7]

you lucky basterd..
those pistons dont even look old....this is like finding gold...

lol, the cylinder walls cross hatchings are still there from the hone. i bet there wasn't but a few hundred miles on the bike after the PO rebuild it. 

i don't want to sound like a tool but i just happen to have my luck these past few weeks. first, found a rare dual disc setup front end for a few bucks and now this which by the way was free. good thing i had a hunch or else this block was off to the recycling center monday

[754]

I am not sure what you think you have, but it is used parts.

So without a full measured report on them they wont be worth a real lot.

if you measure everything and it is tight then it is worth more. Pistons dont appear  be forged, but pic did not show much. If they are cast, some wont want to use them..

If the bores are loose, either worn or [poor machining], then to be useable you will need sleeves at around 250 plus and maybe a cyl.. so putting together that will not be cheap.

 If your rods have bushings in the piston pin end they are modded.. if you dont see this or different bolt heads.. from looking own on them.. no sense in digging. no more treasure unless the crank is knif-edged..

[martino1972]

I am not sure what you think you have, but it is used parts.

So without a full measured report on them they wont be worth a real lot.

if you measure everything and it is tight then it is worth more. Pistons dont appear  be forged, but pic did not show much. If they are cast, some wont want to use them..

If the bores are loose, either worn or [poor machining], then to be useable you will need sleeves at around 250 plus and maybe a cyl.. so putting together that will not be cheap.

 If your rods have bushings in the piston pin end they are modded.. if you dont see this or different bolt heads.. from looking own on them.. no sense in digging. no more treasure unless the crank is knif-edged..

sounds like you downgrading it cause you wanne buy it....

[rbmgf7]

i also noticed on the face of the valves had a symbol stamped on it. it's a diamond with a theta in the middle. all my stock ones are plain. kibblewhites?

edit: i just got some more pics loaded

[MRieck]

The valves are stock. You have an RC cam sprocket. I'd say those are Wiseco 915cc pistons (67.5mm) with an XC ring pack.

[rbmgf7]

ok, i've been searching the net about this cam or it's manufacturer. it appears like Crower, Crane, or Textron-CWC made it. i've seen more posts about automotive applications. haven't seen any on motorcycle.

i went ahead and measured the differences between my stock F2 and the CWC. i encompassed the entire lobe by measuring the point at which the valve is closed to the peak opening using a caliper.

i just hope i have the right intake and exhaust lobes, they may be backwards.

stock (in/ex): 1.422"/1.402
cwc (in/ex): 1.470/1.445

there are also a couple more markings. there's a "D1" and "C1" but i can't seem to make this last one out. it looks like "L 14"

tried getting some more pics but my camera sucks on focusing

[martino1972]

i think you should stop worrying about all those parts and just donate them to a poor canadian that's starting on his 1973 cb750(wink,wink)..............let me worry what parts they are...

[rbmgf7]

i think you should stop worrying about all those parts and just donate them to a poor canadian that's starting on his 1973 cb750(wink,wink)..............let me worry what parts they are...

lol, dynoman carries 915 head gaskets and total seal appears to list rings so this kit will live another day...and that day will come when i have more money and time 

[rbmgf7]

thought i'd move on for the time being and check the rods. haven't cracked the cases but was able to remove a couple studs to pivot the pistons a bit more...

...there it is "RC" stamped on one side with two "U's" and three dots on the other.

i'll consider this entire treasure find an early b-day present for myself 

[Big Jay]

It is an aftermarkt billet cam. The CWC is the billet manufacturer. There must be other markings either stamper or written with a viba pencil to identify the grinder and grind. Might be one of our X grinds or H360.  Sold a lot of them with Wiseco 915s.  I would hope that has an aftermarket rod in it.

Retainers don't look titanium. Try a magnet on them.

Jay

[rbmgf7]

It is an aftermarkt billet cam. The CWC is the billet manufacturer. There must be other markings either stamper or written with a viba pencil to identify the grinder and grind. Might be one of our X grinds or H360.  Sold a lot of them with Wiseco 915s.  I would hope that has an aftermarket rod in it.

Retainers don't look titanium. Try a magnet on them.

Jay

lol, it just caught my eye. i put the retaining washer back on the end of the cam and didn't think to look under it. i have:

"RG295B" and "38H"

the first serial looks like there's a "C" on top of the "G" so i'll probably guess it's "RCG295B".

you got me on the retainers. they're ferrous. maybe some alloy like 4130. i'll take it all apart later on to inspect and clean.

[Jerry Rxman Griffin aka MuthaF'er]

RC made 2 different rods using stock Honda rods. Both were stronger rods. Both were shot peened but the Super Rods had larger bolts. Compare the bolt diameter to stock bolts. I'd also expect to find bronze bushings inserted into the small end.

[rbmgf7]

RC made 2 different rods using stock Honda rods. Both were stronger rods. Both were shot peened but the Super Rods had larger bolts. Compare the bolt diameter to stock bolts. I'd also expect to find bronze bushings inserted into the small end.

i'm not sure how to remove the clip restraining the piston on the wrist pin. i looks like an overlapped lock washer. something tells me this is a one time deal and the only way to get the whole assembly out is to unbolt the conrod from the crank.

[MRieck]

RC made 2 different rods using stock Honda rods. Both were stronger rods. Both were shot peened but the Super Rods had larger bolts. Compare the bolt diameter to stock bolts. I'd also expect to find bronze bushings inserted into the small end.

i'm not sure how to remove the clip restraining the piston on the wrist pin. i looks like an overlapped lock washer. something tells me this is a one time deal and the only way to get the whole assembly out is to unbolt the conrod from the crank.

Like a Spiroloc?

[goon 1492]

man looks like fun, rebuild and drive it like you stole it, then don't brake till you see god! Oh yeah if ya don't want that dual front disc setup give me a buss up here in KC and ill put it to good use for ya

[rbmgf7]

RC made 2 different rods using stock Honda rods. Both were stronger rods. Both were shot peened but the Super Rods had larger bolts. Compare the bolt diameter to stock bolts. I'd also expect to find bronze bushings inserted into the small end.

i'm not sure how to remove the clip restraining the piston on the wrist pin. i looks like an overlapped lock washer. something tells me this is a one time deal and the only way to get the whole assembly out is to unbolt the conrod from the crank.

Like a Spiroloc?

yup. just learned something new.

found a tool to remove them and pow! right in the kisser! $90! i think i'll hold off removing the pistons. i'd rather not try mangling them trying to remove the locs. unless....someone here has one they're willing to lend... . i'll try calling around town. doubt anyone will have one. seems like a performace shop tool.

[Big Jay]

Nice cam
RC295B  Lifts, In .390", Ex .360"  Their durations were taken at lash (.004" In, .006" Ex ) so that made then seem very long. IIn 306 / EX 296. Probably in the 260 range at .050"
Ground to run 105 lobe centers.

[Big Jay]

Not sure if the Spyro locks are still available. Be careful taking them out. The way the grooves in the pistons are cut, you can not put regular clips in it. Tale out only one from each pistons if you need to take the pistons off the rods. I have four new ones if you need them.

Jay