Knocking and power loss

Hi all, hope you had a happy 4th! I recently had some problems with my KZ. Over the winter I had the valves and valve seats cut, the head re-shimmed, new piston rings installed, a hone job done, new gaskets, an installed a new Vance and Hines four into one exhaust. Now to the problem, the first couple of times I rode the bike with the fresh rebuild it ran great! But I got on it once on a straight strip of road and started to hear some loud knocking coming from the motor and looked down to see the oil light had come on. Now every time I try to ride the bike there is a nasty knocking when I put load on the engine. When the bike is revved in neutral it sounds fine, but when I go to take off that nasty knocking comes back. Also, when I ride the bike for more than five minutes the oil light will come on at idle, if I rev the motor up to just 1500 rpm the oil light shuts off. When the oil light comes on at idle is about the time that the motor starts to knock REALLY loud and looses power. When I first start riding it is has a light knocking sound but runs great and the oil light stays off, it is only after a couple of minutes riding that all these problems crop up (power loss, oil light at idle, LOUD knock).Sorry for the long post, but thanks for looking.

Oil light means the oil pressure is dropping very low. Knocking sound at the same time confirms oil is probably not getting to the main and rod bearings. Loud knocking from an engine has always been rod bearings in my experience. An exhaust leak will make a kind of "crack crack" sort of noise that does get a lot louder when you get on the throttle, but doesn't really sound like a knock.

First thing I would do is obtain an actual oil pressure gauge and read what's going on. If you do have low oil pressure, the first suspect is the oil pump. After that, it's probably bottom end bearings.

jmargrav wrote:

Hi all, hope you had a happy 4th! I recently had some problems with my KZ. Over the winter I had the valves and valve seats cut, the head re-shimmed, new piston rings installed, a hone job done, new gaskets, an installed a new Vance and Hines four into one exhaust. Now to the problem, the first couple of times I rode the bike with the fresh rebuild it ran great! But I got on it once on a straight strip of road and started to hear some loud knocking coming from the motor and looked down to see the oil light had come on. Now every time I try to ride the bike there is a nasty knocking when I put load on the engine. When the bike is revved in neutral it sounds fine, but when I go to take off that nasty knocking comes back. Also, when I ride the bike for more than five minutes the oil light will come on at idle, if I rev the motor up to just 1500 rpm the oil light shuts off. When the oil light comes on at idle is about the time that the motor starts to knock REALLY loud and looses power. When I first start riding it is has a light knocking sound but runs great and the oil light stays off, it is only after a couple of minutes riding that all these problems crop up (power loss, oil light at idle, LOUD knock).Sorry for the long post, but thanks for looking.

my opinion and like cornholes everyones got one, pump went bad and something is gone in bottom end....i dont know if your bike has a roller bottom or car-like bearings....if they are car like, she s done....time for a rebuild....i m not up on my smaller motors...i m sure the more smarterer will respond...good luck man.....keith

I am pretty sure that my 82 has the plain type bearings, not the roller bearings. I wanted to get an oil pressure gauge to make sure my oil light was working correctly. I figured something was toast , I just did not want to admit it, I was looking for a simple answer/fix. Where could I get an oil gauge? Could I find all the fittings necessary at any auto parts store? What would cause the oil light to stay off when the bike is cold?

jmargrav wrote:

I am pretty sure that my 82 has the plain type bearings, not the roller bearings. I wanted to get an oil pressure gauge to make sure my oil light was working correctly. I figured something was toast , I just did not want to admit it, I was looking for a simple answer/fix. Where could I get an oil gauge? Could I find all the fittings necessary at any auto parts store? What would cause the oil light to stay off when the bike is cold?

The viscosity is highest when cold so that's when you would get maximum pressure. You might get just enough pressure cold to keep the light off. In cars, the light usually comes on when the pressure drops below about 8 psi.

jmargrav wrote:

Where could I get an oil gauge?

I got mine at JC Whitney. There are probably other places that sell them.

Harbor Freight if there's one around you will have the cheapest price on one that I've seen.