non GS. Pic of failed rod bearing. SV650

[Redman]

Helped son last night. With engine tear down.
Could hold piston and move it in and out on crank -klunk - klunk.
Got down to this.
Rod bearing look like it got hot and near melted and thinned out. Have yet to remove the other rod, but it feels okay (not like this one).

On the SV650 both rods are connected to crank on the same place on the crank (pin?), well, right next to each other (not forks like Harley). CAn slide the other rod to the side, so can compare the place under this rod to the place under the other rod. The place on crank under this rod is just slightly not as shiney, but no real marring or gaulling or scratches.

Any way, any insite on possible cause of this?

SOn has had bike for 3 years. We did notice yellow paint pen markings on bottom of engine (a 5 digit number). Wondered if it was a salvage engine. After having it for a short time it becaome apparent that it was a repaired wreck.

[catbed]

glad i dont have to worry...


lack of oil maybe? on the bearings, is it shiny?

and i thought harleys had connecting rods next to each other, as you described?

[Fast Doc]

It has to be an oil flow/pressure issue. Maybe a blocked passage that affected only one rod. Make sure you get the cause 100% diagnosed and repaired, or you'll sing the same song again.

Just my 2 cents.

Your son is lucky to have a dad to help him with such issues!

[Dave8338]

From the looks of things, it appears as though you caught things JUST in time!!! Not sure why it let go but I'm also not convinced that it was oil related unless there was debris that somehow lodged in the oil gallery for that rod. Oil restriction (were it pump/ filter related) should have shown up on the top end first.

The more I think about it...you mention that it was a wrecked bike. If the cases were not scratched / dinged up...I'll bet the hack that "replaced" them, left some junk on the inside of the bottom end that eventually found it's way to the oil gallery for that rod.

[tkent02]

Rods that have gotten hot are usually blackened?
Did you clean it before the pic was taken?
Don't see any black?

The ones I have seen heated up were from the caps being installed on the wrong rods, the bore is only round when matched with the correct cap. Has this engine been assembled by someone other than the factory?

Could certainly be an oil problem.

[Steve]

... i thought harleys had connecting rods next to each other, as you described?

No, Harleys have cylinders that are perfectly inline with each other, not offset by the width of a connecting rod.
To accomplish this, they use a "knife and fork" arrangement, where one of the rods is split, and straddles the other.

.

[Zook]

I think if it was an oiling problem the bearing and its journal would have been destroyed.
IMO this might be an instance of the wrong clearances due to someone "fixing" an engine to be sold without repairing the bearing journal. They just slapped a new rod bearing in it and allow the same thing happen again.

HDs are basically two cylinders from a radial aircraft engine. Their rods use a "knife and fork" arrangement on a single, shared crank journal. Their cylinders are in line with each other.
The SV uses a journal for each rod, but they are on the same crank throw. One cylinder is offset slightly to one side.
Turn the engine sideways as on a Guzzi and one jug will be closer to your knees than the other.

[Dave8338]

No, Harleys have cylinders that are perfectly inline with each other, not offset by the width of a connecting rod.
To accomplish this, they use a "knife and fork" arrangement, where one of the rods is split, and straddles the other.

.

Did they ever run a single "Y-rod"?

[Zook]

Did they ever run a single "Y-rod"?

Not to my knowledge, at least from the "Knuckle" on up.

[Steve]

Turn the engine sideways as on a Guzzi and one jug will be closer to your knees than the other.

Same idea applies on a BMW twin or a Wing. One bank of cylinders is a bit farther forward, by the width of a connecting rod.

.

[Sunburn]

they just don't build them like they used to. lol

[Zook]

Same idea applies on a BMW twin or a Wing. One bank of cylinders is a bit farther forward, by the width of a connecting rod.

.

But on the Wing there are two crank throws.
AIIRC there are two throws on the BMW because the pistons both go out and in at the same time. IOW both are at TDC at the same time, except one is on compression and the other on exhaust, whereas the Guzzi has one piston at TDC, the other at BDC.

[Suzuki_Don]

It may not be an oiling problem, but it needs to be checked anyway. Source an oiling diagram and study it carefully. It is very important to fully understand how the oil flows from "go to woe".

Check gauze pickup in sump, check internals of oil pump for scoring and other damage, check oil filter and by-pass valve. Cut filter in half and check paper element for metal particles that will give a clue to what has gone on before.

Then follow oiling galleries throughout the motor, proble with wire, use compressed air. make sure all is OK before reassembling the motor. You MUST understand how the oil flows through the engine to be able to trace it out methodically and alleviate any problems. I've just done this on my 550, there are no short cuts. We don't want it too happen again do we.
Cheers
Don

[rapidray]

You also need to send the crank out to have it magnafluxed to check for cracks. If it checks out ok, send it out to have the journals polished. Mic the journals & get the CORRECT size bearings & get it ready for reassembly. It is good you caught it before it killed the journal & broke the rod. I know that motor has oil starvation issues if wheelied much so it IS possible that's what it's from. Ray.

[rphillips]

Looks, to me, like that bearing shows the advantages of roller bearing on cranks.