Topic: bottom end knock , metal shavings in oil HELP

[hoekakes]

alright so i recently traded my truck for a motorcycle ..now that ive got the motorcycle im sure the carbs are out of adjustment the guy said he cleaned them and couldnt get the rubber boots seated right .. anyway i got it started but theres a knocking coming from the lower end while the engines cold .. it almost goes away completely when its warmed up then i went to change the oil and found a bunch of metal shavings .. how much trouble am i in right now ?

[Scott S]

 First of all, what bike? Model and year, please. You posted in the Hondamatic section....do you have the semi automatic CB750?

 The bottom end knock could be carbs out of sync, and most likely is, since you say someone has been working on them.
 Do the 3K mile tune up and vacuum sync the carbs.

 Pics of the shavings would be helpful. But start with the tune up and carb sync.

[hoekakes]

ive got a 1977 cb750a , the shavings look like glitter , i cant get a good picture right now since its sitting at my friends house

[754]

Sounds like it needs a new bottom end,as in crank and bearings.

[hoekakes]

exactly what i was afraid of , does anyone buy bikes with problems like that .. its a complete bike with vetter fairing and even the original owners manual

[754]

Do yo want to pull the motor and fix it..afew hundred for bearing sand gaskets, may need a used crank.. You can usually pick up a wreck for cheap, swap motors.

[hoekakes]

i did find a crank with bearings and rods on ebay for 120 but im not sure im capable of tearing something like this down and gettingbit back together right

[scottly]

Just how much "glitter"? Was the glitter in the oil filter housing, the oil pan, or the pan you drained the oil into? Does the glitter stick to a magnet? Does the oil pressure warning light come on when you first turn the key on, but go out once the motor is running?

[hoekakes]

i dont have any of the oil at hand right now but there was a good amount that settled to the bottom of the pan i drained it into, oil light does come on until i turn it over which i assumed was normal

[scottly]

Yes, it's normal for the light to go out once the motor is turning. If it stayed on with the motor running, then a lack of pressure from a worn bottom end might be the cause, but since the light goes out, I wouldn't be too quick to tear the motor apart just yet.

[hoekakes]

weve got the carbs off it right now and slide number 2 is open further than the other 3 and the butterfly valve doesnt close as far as the other 3 .. im not seeing any thing that adjusts that on these carbs lol im clueless but want this bike to run without issues by next summer

[stikman]

The bottom end knock could be carbs out of sync, and most likely is, since you say someone has been working on them.
 Do the 3K mile tune up and vacuum sync the carbs.

 Pics of the shavings would be helpful. But start with the tune up and carb sync.

+1.  These motors are notorious for a bottom end knocking sound at low idle with carbs out of sync.  Certainly worth trying that first.

[Randy Nevrotski]

I read your post what did you ever end up finding out the problem . what did you do

[jukku]

Something like this?
http://forums.sohc4.net/index.php/topic,179354.0.html