Author Topic: CB 750 K2 oilmpan debris mystery (Read 5510 times)

Hastenbrucke · « **on:** September 21, 2013, 03:34:21 AM »

dropped the oil pan on my K2 today and found some very scary debris.
Some ferrous some not.
My bike has done 20575 miles and was running ok albeit poor idle. Carbs re built.
I am told my bike had a big bore kit installedmin75 (836).
I am the third owner.
Before I split the motor and go through a massive re build does anybody have any idea what this junk is or where it may have come from.
The larger bits are very thin like shavings and are blued as though they have seen heat.
Any help would be really appreciated....I won't sleep well tonight.
Pics are included.
I am stumped!!!!!

ekpent · « **Reply #1 on:** September 21, 2013, 04:01:11 AM »

Somebody must have been drinkin' a Heiniken beer when it was put together

Some of that stuff does look pretty big. Is the piece your holding steel ?

Hastenbrucke · « **Reply #2 on:** September 21, 2013, 04:15:11 AM »

LOL???yes the piece being held is very thin metal. It is blued which I gather means it has seen heat....my thoughts were clutch.?

ekpent · « **Reply #3 on:** September 21, 2013, 04:20:46 AM »

Are you doing the "massive" re-build based on what you found in there or was it something you had planned anyways. We all like these mystery oil pan threads sure others will chime in with guesses today.

Hastenbrucke · « **Reply #4 on:** September 21, 2013, 04:24:46 AM »

Well no I wasn't planning a re build but based on what I saw in the pan maybe it's on the cards. I just want to make sure it's all as it should be.

scunny · « **Reply #5 on:** September 21, 2013, 04:26:06 AM »

more beers for better ideas.
looks too thin to be clutch related imho. any noises from the motor ?

Ace · « **Reply #6 on:** September 21, 2013, 04:32:01 AM »

Having inspected the contents of the oil pan, I'm stumped as to what it could be from. Apart from the beer cap

the piece of metal is like a thin sheet, and reasonably flexible. It reminds me of a metal coating that has been shaved off, not aluminum either. As for the rebuild...I hope there is no need to.

ekpent · « **Reply #7 on:** September 21, 2013, 04:38:15 AM »

It would be nice to know if the oil pan was ever taken off before. You may be the first, was there any signs it had been off in the past. Apparently the top end has been apart if it indeed has a big bore kit ? Sometimes stuff gets dropped in there etc you just never know. Does it have an aftermarket oil pressure gauge installed by chance ?

Hastenbrucke · « **Reply #8 on:** September 21, 2013, 04:58:59 AM »

I suspect the oil pan has not been off before. The engine wasn't noisy other,than a bit of cam chain and slightly noisy clutch. Pretty normal though. No aftermarket pressure guage. We did find broken valve cover thread which worried me. This MIGHT be the shiney flakes as they are non ferrous.

Pecantree · « **Reply #9 on:** September 21, 2013, 07:19:32 AM »

THAT would keep me up at night

What did the oil filter look like?
Pull the clutch, that's a pretty easy next step.
I'd almost say a shield from a bearing. But I don't remember any internal bearings have shields.
And that would have trashed the bearing.
I'll be following your thread.
Good luck
STeve

PS. A good hack is to remove the magnets from a disk drive and stick them to the oil filter.
You can catch any ferrous stuff that goes thru the system. Just clean them and move to the new filter when you change them. Learned about this from this forum.

70CB750 · « **Reply #10 on:** September 21, 2013, 07:38:55 AM »

Subscribed.

Don R · « **Reply #11 on:** September 21, 2013, 09:05:49 AM »

I spun a rod bearing once and it looked like that. That would make noise though. there were pieces in the rocker covers and valley too.

martin99 · « **Reply #12 on:** September 21, 2013, 10:31:08 AM »

My first thought was rod big end bearing. Don't know if those would be ferrous or not.

Are you sure it's not flaking paint? Like the stuff you use on porous cases? It's often done as a preventative measure.

You could try dropping a bit in thinners or paintstripper and see what happens.

Hastenbrucke · « **Reply #13 on:** September 21, 2013, 11:37:56 AM »

Thanks everyone for your replies.
If it was a rod and bearing would there not be an issue with the bike running?
There didn't seem to be any unusual noises other the normal cam chain rattles which went away largely with tension.
Definitely not paint as it sticks to the magnet. It is very thin metal like its shaved.
I will pull the clutch and have a look next.
Nothing in the oil filter and the oil pump screen looked pretty clean.
The rollers were all intact on inspection whilst I had my head under there.
Not entirely sure where to go if its not clutch...

Thanks again everyone....
ACE, it's 2.40 am ..told you!!!!!

Pecantree · « **Reply #14 on:** September 21, 2013, 11:47:26 AM »

Kinda remember Hondaman writing about failed crank bearings.
The engine was still running good with a trashed bearing.
I think he was talking about how beafy these engines were.
Or
I might just be smoking crack.
Good luck with this.
Steve

Pecantree · « **Reply #15 on:** September 21, 2013, 12:45:39 PM »

Quote from: rotortiller on September 21, 2013, 12:24:27 PM

Main and rod bearings are not ferrous.<<<<<<<<<snip>>>>>>>>.

Oh yeah, Forgot about that.

Steve

lucky · « **Reply #16 on:** September 21, 2013, 12:59:30 PM »

It could be debris from an earlier rebuild.
I would remove some covers and use a bright LED flash light to look around.

scottly · « **Reply #17 on:** September 21, 2013, 01:12:21 PM »

Quote from: Pecantree on September 21, 2013, 12:45:39 PM

Quote from: rotortiller on September 21, 2013, 12:24:27 PM
Main and rod bearings are not ferrous.<<<<<<<<<snip>>>>>>>>.

Oh yeah, Forgot about that.

Steve

The bearing shells have a thin layer of steel on the outside diameter.

754 · « **Reply #18 on:** September 21, 2013, 01:24:12 PM »

Actually the bearings are about 75 or more% steel ,with a thin layer of bearing material on the running surface. .looks like it could be part of a bearing shell

Ace · « **Reply #19 on:** September 21, 2013, 04:12:42 PM »

If it was from a rod or main bearing, how did a piece(s) that big get out and not be destroyed in the process? If a main bearing did fail, would that be enough to take a cut/shave off the crank looking like what was found (something sharp and just in the right place)? It would have to a be a complete failure/destruction. The piece has been blued remember as if excessive heat got to it. I've done a big end bearing due to lack of oil in the bottom end, blueing of crank/rods/pistons etc. Lucky when it went bang it all kept inside the cases but I didn't tear it down, left that to a professional due to lack of skill many years ago.

Thinking from top of the engine down, shouldn't be rocker/valves/cam, working down pistons and barrels doubt that due to feel of it, not gears/primary hub/clutch or rods, if it was generator or stator then how did it manage to get into sump due to size, doubt clutch but running out of ideas....

Hastenbrucke · « **Reply #20 on:** September 21, 2013, 05:21:23 PM »

This is a picture of the pan at removal if this helps?

ekpent · « **Reply #21 on:** September 21, 2013, 05:27:37 PM »

I see a cool "F" in the middle of the pan--do you see it also. ?? Might be a sign

754 · « **Reply #22 on:** September 21, 2013, 05:38:01 PM »

Me too

scottly · « **Reply #23 on:** September 21, 2013, 08:26:33 PM »

Bet a cyber beer it's a rod bearing; if it was a main, there would be more aluminum debris. Also, to hammer steel like that would mean it was hammered between two pieces of hard steel, like the crank and a rod. Just guessing, as I can't come up with any other explanation.

754 · « **Reply #24 on:** September 22, 2013, 08:27:30 AM »

If they didnt have a steel backing they would probably bend while assembling.

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Author Topic: CB 750 K2 oilmpan debris mystery (Read 5510 times)