Rod knock...I think....

[scottynoface]

Originally Posted by hardlydangerous

usually a rod bearing you can hear knocking even if the engine is just turning over under compression (spark plug wires removed) crank bearings need to be running before they are heard in most cases.

Interesting...something to do with the oil heating up and making it easier to hear once running?

Just curious.

[05RedKat600]

No, just the crank moving fast enough to shake around a bit. Remember that a rod stops twice each revolution, so at each stop you'll get a knock from a rod. Cranks don't stop, so you need to spin them up to hear the bad bearing.

[scottynoface]

Originally Posted by 05RedKat600

No, just the crank moving fast enough to shake around a bit. Remember that a rod stops twice each revolution, so at each stop you'll get a knock from a rod. Cranks don't stop, so you need to spin them up to hear the bad bearing.

Interesting.

Makes sense. Replaced the crank bearings and big end bearings on the RM last time just for ****s and giggles.

The crank didnt seem to have much runout, but it DEFINITELY needed some new seals...what a mess...it was like sandy peanut butter down there

[05RedKat600]

Your RM uses roller or needle bearings. The Kat uses bearings like a car engine. Also, if one goes bad, there are 4 others to support as I believe the Kat is a 5 main bearing engine....but that doesn't last long. Also, the knocking is only when the rod next to the main bearing is near the top or bottom of the stroke. More stress on the crank at that point.

[scottynoface]

Originally Posted by 05RedKat600

Your RM uses roller or needle bearings. The Kat uses bearings like a car engine. Also, if one goes bad, there are 4 others to support as I believe the Kat is a 5 main bearing engine....but that doesn't last long. Also, the knocking is only when the rod next to the main bearing is near the top or bottom of the stroke. More stress on the crank at that point.

Oh I understand, just interesting. I've torn a few I4's down to that point but it's interesting to listen to people who actually have a clue

[Mojoe]

Originally Posted by 05RedKat600

No, just the crank moving fast enough to shake around a bit. Remember that a rod stops twice each revolution, so at each stop you'll get a knock from a rod. Cranks don't stop, so you need to spin them up to hear the bad bearing.

you are correct, but you should add that this applies to both ends of the rod, which includes wrist pins, which can just as easily be the problem.

[scottynoface]

Originally Posted by Mojoe

you are correct, but you should add that this applies to both ends of the rod, which includes wrist pins, which can just as easily be the problem.

Again, my only experience with a blown wrist pin bearing has been on my RM (needle bearing) but I never noticed it until I took the jug off to replace the top end and saw the sloppiness...I mean the ring allows for a certain amount of cushion and when you have four cylinders the others can kinda compensate...

OP needs to tear that sucker down to make sure.

[Mojoe]

Originally Posted by 05RedKat600

Your RM uses roller or needle bearings. The Kat uses bearings like a car engine.

have you always referred to them as bearings? I ask because it has only been the last ...oh 10 years maybe, and on forums such as this that I see them called bearings. during my HS years where I studied mechanics, and the few years after that when I worked as a mechanic, and during our racing years, everyone referred to them as inserts. it was crank inserts, and rod inserts....never heard anyone call them bearings.

I am not questioning which is right or wrong or anything like that.....just curious is all.

[05RedKat600]

The rings don't cushion anything. The piston is free to move in the rings. There is a fine film of oil that helps keep it centered, but really that's it. On a worn motor, you see the marks in the cylinder from the piston. It's typically a mark on the front of the wall, and another on the back. That's normal wear from the piston skirt as it moves front to rear with the change in the stroke. All the rings do is seal the cylinder and wipe the oil off the cylinder walls.

[scottynoface]

Originally Posted by 05RedKat600

The piston is free to move in the rings.

So we're saying the same thing

Either way...OP needs to either spend some time or buy a new engine.

Afterall, it's a Katana 600, and you can get one of those engines for cheaper than replacing a bearing. Hell almost as cheap as the bearings themselves