[Mojoe]

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.

the wrist pins are designed to allow a certain amount of side to side motion between the piston and the connecting rod. as all metals have a certain amount of expansion and contraction between hot and cold, it allows for a bit of "play". even cylinder walls can "expand" to a certain degree, but that is not to say that expansion is consistent and uniform. the side to side play of the piston to the connecting rod compensates for this. without it, the chances of snapping a rod increases. plus there is the fact that most blocks are cast, which means alignment of cylinders can vary to agree, which is another reason for side to side play.

side to side play is needed.....but there should be no up-down play between the rod and piston.

there is a fairly easy way to check if it is rod bearings without completely removing the engine, as long as you can get the head off, but it's a two man job.

here is how:

1) remove head

2) put a socket on front sprocket nut

3) turn engine over so #1 piston is at top of cylinder. then take a big screwdriver and hold the end of it against the top of the piston....straight up and down, perpendicular to the piston, and apply a bit of pressure to it.

4) have you buddy get a strong arm the socket on the sprocket nut and start rocking the engine back and forth. not much...just enough to make the piston move slightly. if you have any slop in your rod bearings, and are paying attention, you should feel a slight "clunk" through the screwdriver if your rod bearings are bad. repeat this procedure with the piston half way down, then all the way down, then half way back up again. do this on all 4 cylinders.

I should advise that not everyone has the "feel" for this test. my dad does. if you have a rod knocking in any car engine, he will be able to tell you exactly which one it is.

[BareKat]

Oh, the magical mystery katana engine knock.

Been there done that.

I removed the engine, took it completely apart and found no damage what so ever.

I'd recommend you drive the thing until the motor grenades then you can find the fault.

I wasted money on a new cam chain tensioner before I stripped the motor down too.

Here is a video of my bike before I replaced my engine.
[ame="http://www.youtube.com/watch?v=ZNyf2EZRHSQ&feature=g-upl&context=G254948aAUAAAAAAAKAA"]Katana engine noise 2 - YouTube[/ame]

[Mojoe]

ouch....that sounds nasty.

[BareKat]

hehe, it use to sound nasty... the motor is now in a big box in tiny pieces. I showed it!

ouch....that sounds nasty.

[Mojoe]

I removed the engine, took it completely apart and found no damage what so ever.

I'd recommend you drive the thing until the motor grenades then you can find the fault.

the only way you are going to tell what is wrong by taking it apart is by taking EVERYTHING apart, then visually inspecting each bearing, as well as plasti-gauging them to verify clearance. however, once you are in that deep, you might as well just replace all the inserts.

hehe, it use to sound nasty... it is now in a big box in tiny pieces. I showed it!

so you actually blew it? did it go out with a bang, or a whimper?

speaking of rods....my gf ran our mower out of oil while I was gone for the weekend, but didn't tell me something was wrong. I go out in the garage that week, sit on the tractor and turned the key. it clacked a bit, then I give it a bit of throttle that was it. SNAP....then clack clack clack as the crank spun down. at least it didn't punch a hole through the block, as broken rods often do, so I might be able to rebuild it. I hope so....it's an expensive briggs and stratton 16hp that goes for close to a grand. I have my JD tractor, but still, I hate to just toss the briggs away.

[BareKat]

Naw, I just started at the top and worked my way to the bottom end. I then had a shop split the case and check the crank... nothing but normal wear. This video is after I pulled the cylindes off and the bottom end was tight no play at all. [ame="http://www.youtube.com/watch?v=dafh5YzniJc&feature=g-upl&context=G27405f9AUAAAAAAAHAA"]bearing check 001 - YouTube[/ame]

In the end it was cheaper to buy a previously enjoyed engine than reassemble my original mill.

[hart_57]

I'm not having any loss of power though, wouldn't something like that cause a loss of power or something?? and rebuilding is out of my range of mechanical ability, I would just swap motors in that case

[BareKat]

I didn't have any power loss either.

[88kat-rider]

No . You won't likely have a loss of power.

It's most likely a bearing or some rotating part and it will fail eventually. The noise is an early indication of this.

I would drive it til it ****s the bed. Prepare to swap motors or rebuild it .

[hart_57]

I think that is what I am going to do, I found a motor with 7k on it out of a 06 600 for $400 that I can probably get this weekend if all goes well

[Nut-Nut]

I'm not having any loss of power though, wouldn't something like that cause a loss of power or something?? and rebuilding is out of my range of mechanical ability, I would just swap motors in that case

Most engines run their best right before the blow up.... the extra play, where ever it is, causes less friction, allowing for a bit more power...

[Mojoe]

I'm with the guys who say drive it til it blows. unless you do a full blown rebuild, which isn't cost effective at all unless you are going with a bore kit at the same time for some added power, you are better just to swap the engine.

[hart_57]

I think I'm pretty set on doing that. I might do a rebuild on this motor when I swap so I can sell it. Any opinions on whether its worth the work or not?

[BareKat]

No it won't be worth your while. Bearings alone for my old engine would cost more than a "previously enjoyed" engine.

With the number of bikes crashed there is always a supply of engines on the wholesale market.

I'm keeping my old engine for case parts since my original motor wasn't crashed... all the side cases, oil pan, etc. are in good shape in case I need 'em.

I think I'm pretty set on doing that. I might do a rebuild on this motor when I swap so I can sell it. Any opinions on whether its worth the work or not?

[scottynoface]

I think I'm pretty set on doing that. I might do a rebuild on this motor when I swap so I can sell it. Any opinions on whether its worth the work or not?

A Katana motor that isnt an 1127 or 1052 is worth about $300. The rebuild would cost way more than that.