my engine sounds REALY bad it has this knocking sound.

i am thinking my rod bearing is shot, so i may have to either toss the bike or rebuild.

what are your thoughts

 

Yea, I think you have a big problem, but it is not in the engine!

 

ouch

 

Don't mind him.. He's frequently off his meds - just search on all his posts for a good read on a tortured soul wanting to spread the misery..

 

Thx

still leaves me sitting with what to do with the bike. perhaps a good sleep will clear my head.

 

I was hoping someone else would bring up this point since when I do some tend to think I'm just trying to sell parts. I'm not, I am just pointing out this possibility.

Have you gone to a manual cam chain tensioner? I noticed the rapping goes down significantly as you bring up the rpm. That could be the chain is pulled tight on the front run as rpm increases, the tensioner can hold the chain play in check then. It is when the throttle is backed off and idling the rap is really loud. Reminiscent of the noise my 650 made. That is when the cam drive can whip around a bit, pushing the tensioner in and it snapping back out.

If it has a manual tensioner and it is properly adjusted, if that rapping is still there, now you could be talking bearings.

If it doesn't have the tensioner swap, it's a heck of a lot cheaper to try a new tensioner than to tear down an engine only to find out it was a trashed tensioner. The tensioner will look fine, but you have to pay attention to the wear pattern that will be visible on the plunger rack teeth and the back side of the plunger rack will be polished over 1/4-1/2 inch where it is sliding in and out. If that bad it is also to the point where there is risk of jumping timing with the chain at the crank - chain breakage or valves meet piston.

 

atm a manual is installed and set just tight enoug so tha the buzzing is gone ( defective auto chain buzzing at 5-6k rpm)

set during cold engine as loose i dare so it will not be to tight when warmed up (i hope)

 

That is your piston hitting the cylinder wall, quite normal.

 

In car engines, if the rod bearing has too much clearance, the knocking volume increases with the load on the engine. I would guess that this would carry over to cycle engine.

Ride on
Brewster

 

You're right on the tensioner adjustment unless it is too loose, but I don't think so. It would have to be way out for that kind of rattle, but you will know if you do the following:

You need to locate the noise - where is it coming from - more specifically. If you can't tell by listening in general you can use a long handle screwdriver, but I prefer a mechanic's stethoscope (less than $4 at Harbor Freight) placing the tip around different places on the head, cylinder, and cases. When the noise is the loudest you have identified where it is at.



Piston rock should be loudest on the front or back of the cylinder, cam drive would be in the area of the cam drive, valves in the head area, and bearings in the case area. See if you can get the noise localized. Then you will know what to do.