Connecting Rod C2C Length

[ayedurand]

So I've spent WAY too much time searching and am finally breaking down to ask.

What is the center-to-center length for the GSXR750 connecting rods?

85-87 = A

88-90 = B

91-95 = A

96-99 = 4.193 inches (106.5mm)

The Carillo rod part number is CRS750-87

A Yoshimura-Carillo rod part number CRS751 (for stroker build?)

I have a terrible idea of using 1100 sleeves and pistons in a 750W jugs block.  I have no idea what the pin to crown height is for the 1100 pistons but I need to start somewhere.  I'm trying to be as cheap as possible using only junkyard parts.  Hell, the project may never even happen but I can't sleep until I have the answers.

 

Please help.

[dupersunc]

The long stroke 750s 85-87 & 89-92 have different wrist pin size to the 1100 pistons. 

88-89 short stroke has a different big end size to all the other 750s from 85 to the Srads . 

[ayedurand]

I appreciate your considering downstream affects. You are correct and this is a problem that I will have to address. Off the top of my head is that the wrist pin hole could be bored out. More exotic things could be done to the pistons. 

However, none of it matters if I can't calculate TDC height. 

Shims and a devil may care attitude will get me all sorts of lovely unintended consequences. (timing chain?) 

The thing is, the information regarding the C2C distance is not available on the internet. I've looked.

[ayedurand]

So I have figured out the dimensions.  I got a used set off of Eblag and measured them.  My tools aren't fantastic.  In fact, I am rounding up to the nearest half millimeter.  There doesn't appear to be any bike manufacturer building connecting rods without round numbers.  

GSXR750W Connecting Rod Dimensions (nominal)

Center to Center:   109.5mm

Big Bore Diameter:   37mm

Big End Width:   21mm

Small Bore Diameter:   18mm

Small End Width:   16mm

Wrist Pin Oil Holes:   3mm at 45 degrees clockwise and counterclockwise on rod body center line

Chamfers all appear nominal and the forging is not terribly clean.  Flashing is gone but small end concentricity for the raw material to hole bore isn't spectacular.  I haven't thought too hard about how they went about balancing the rods.  It may be as simple as the grinding marks  near the rod bolts (9mm x 35mm).  The rods I have are a little rusty in parts.  I think a wire brush and a little emery paper will take care of the nicks and pits.  The oil film will take care of the rest.

Rod caps have dowel pins to locate the cap.  The orientation has both bearing anti rotation clips on the same side of the bore.  This isn't what I had expected.

ZX-10 pistons are in my future.  They have a 76mm bore and 17mm wrist pins.  They should work nicely for a junk yard big bore kit.  I need to confirm the piston face to wrist pin center line height first but it looks promising.  A 0.5mm wall bronze bush (Ampco 18) will space the pin into the rod.  Custom or made by Crower, not sure.

[Nik]

I saved some photos from the old OSS site, concerning rod dimensions. Unfortunately, I do not know who shared them, but I hope he/she doesn't mind that I share them again. I know you asked for 750 rods, but I share 1100s too, in case others are interested.

Note: I am pretty sure that the GSX-R 1100 86-88 rod C2C is 117.37 (the photo below says 117.4).

 

Edited September 12, 2019 by Nik