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engine rebuild help

Posted: Tue Dec 22, 2009 10:03 pm
by CRGkart44
This is my first 4 stroke engine im rebuilding. I have taken apart and build 2-stroke racing engines, but thats the extent of my motor history.

Over the summer, in September to be exact, my motor all of a sudden started making a loud ticking noise. It sounded like something moving around in the engine, but im not sure. Could have been a knock.

So far, i have the heads off. including the cams and obviously the valve covers. but i have run into a couple of problems.
1. When taking the cams off, the intake cam off easily. just pulled right off after the chain was out of the way. However, the exhaust cam seemed to be stuck in the journals. As bad as an idea is sounds, i had to get a narrow pipe to put in the cam to yank it out. The weird thing is that there were no scratches on the journals, so idk what the problem was. Thoughts?
2. After i got the exhaust cam out, i looked down into the motor. More specifically, After i too the timing chain guide out, i noticed that there was a stray washer and some scoring in there as well. the washer was the exact size of the washers under the nuts holding on the head. But those are on the outside, so how would that have gotten in the engine? plus, i hadent taken those off yet. And each had their own washer. so it seemed to be extra.

So, could this mysterious washer have been dropped down there at one point and finally got picked up and banging around in the motor? I know for sure the motor has been out(complete frame has been painted). So its possible that its been torn down at one point as well. Another reason i think this has been apart at one point is that the cylinders looked perfect. i mean VERY smooth. I neglected to check the compression before i took it apart, but i think the rings are goign to be fine(30k on the odo) I have yet to measure the valves, so it still could be a valve knock. And there is a LOT of carbon on the valves and the piston tops. Meaning RICH. So im going to get a jet kit as well when i get it back together.


ANY help is greatly appreciated.

Mike

Re: engine rebuild help

Posted: Wed Dec 23, 2009 9:53 am
by haunter
washer probably got dropped in during prior service

Re: engine rebuild help

Posted: Wed Dec 23, 2009 10:33 am
by yamaha_george
haunter wrote:washer probably got dropped in during prior service
Hi,
As H said there are no washers inside the engine, so that is a stray!

Just be careful putting the cam chain tensioner back READ the manual before doing it.


Knocks from the engine internals is usually top & bottom bearing wear


CRG, be sure to add your location in your profile OK
THANX Y_G

Re: engine rebuild help

Posted: Wed Dec 23, 2009 11:20 am
by CRGkart44
haunter wrote:washer probably got dropped in during prior service
could be very true. I did notice the crosshatch pattern in the cylinders. So it has been honed recently. Im just waiting for my tools before i can take the valves apart and measure them. So it still could bt a valve knock i guess. Im just really hoping its not anything in the lower end.

Y_G... I would be lost in this 4-cycle if it wasnt for my manual. Thanks for the warning.