Hey guys,

I'm in the middle of a rebuild and I had the crank at the machine shop for inspection. The guy just called me to say the piston to wrist pin clearance is 0.002" and the inside diameter of the small end is 0.947" . He suggests I rebuild it at a cost of $350. I just checked my manual and unless I'm reading this wrong, I'm showing the inside diameter being up to 0.9465" new and 0.948" service limit, and the clearance being up to 0.0019" new and 0.004" service limit. Seems to me I'm well within spec and a new rod kit probably isn't going to be much different. Is there something I'm missing here, or am I using the wrong shop?

Thanks.

Verv650 said:

If the new piston pin is at the top spec of 0.9447", you are only looking at just barely over .002" clearance. I don't think you have a problem providing that the small end of the rod is not significantly out of round.

Has anyone heard that the pig's small end clearance is sloppy compared to other bikes? The crank tech at the shop was saying a normal clearance is 0.0002", meaning 10x less clearance than the XR650L's OEM clearance. Maybe it's bigger because there's no small end bearing?

It depends on what bike it's being compared to. I looked up a CBR600 F4i pin clearance and it's 0.0001-0.0006". I also looked up the XL600 spec and it's the same. The XR600, however, is a little wider at 0.0003-0.0007" with the service limit at 0.003"

I just put my bike together with a measured .0019 or .002 pin to rod clearance. I'm somewhat less than pleased. It makes a racket of clanking from that .002. I plan on changing that rod out in the future.

Quote

I don't recall what my clearance was, but it was just a little under the service limit, so I went with it. In retrospect it was a bad decision. I'm gonna replace the rod this winter. Way to much noise!

Quote

Mr. Crankshaft did my other one for $230 including the rod kit (pro-x) and shipping. He was quick about it also.

cleonard said:

That's unbelievable to me. I realize that 0.0019 is the sloppy end of new, but if you're measuring the same and hearing some noise, that means a brand new pig could conceivably come out of the factory with the same noise. How much noise is it? Do you have to really be listening for it to hear it?

uranys said:

That's a little more understandable, because the service limit is way up at 0.004, so almost double what I'm showing. But even still, you wouldn't think they'd allow for little end knock within the service limit. Maybe Honda doesn't see little end knock as a big problem.

Quote

At first I was going to tear it down right away, but since I have 2 motors and didn't have that much money into it, I decided to go with it. 2k so far and it hasn't let loose yet, but it does sound alarming.

I'm going to leave it and see how it goes. I'll update you guys after it's back in.

I hate to not do something while it's apart, but $350 is a lot of money for me to drop on something that is probably not a problem.