Hey y'all.

My ride is a 99 600 F4. I changed the cam tensioner in it, adjusted it out and took it for a ride.
On the ride, it acted a little different. It struggled after 9k RPM's. I changed out the fuel filter, and broke a line. I put a line on it that ended up being a little smaller. I thought that was it, so I put a properly sized hose back on. Went to start it up, and it was making a tapping or knocking noise. It is also blowing exhaust out of the #1 cylinder carb. The noise seems to be most apparent at the #1 cylinder. Can be heard in the video below:


It has a new APE manual CCT on it. I have checked the time, and it is in time. I have checked the valve clearance, and all the valves are in spec.

Any help or ideas are appreciated! I have been stumped on this for about 3 weeks now. I don't think I'm gonna have her fixed before riding season is done here. :/

 

I'm trying to find a compression tester that will fit this bike. Then I'm going to check the compression in the #1 cylinder. I'm about certain now that there is something wrong with a valve. It's spitting exhaust out of the carbs, and the exhaust is popping.

If it fails the compression test, I'm taking it to a shop. I don't have the time or patience to be messing with valves right now. Really getting slammed at work!

 

Do you have an automotive stethoscope? It'd help you pinpoint where the sound is coming from.

 

I used a long handled screwdriver to do the same thing. The sound is most apparent from the #1 cylinder area. It is definitely coming from that cylinder.

 

I had very similar noise and it was exhaust pipe gasket blowing, I had my fingers in there and could feel no leaks , my mate had a look also , we tried it hot n cold , could feel nuthin, we were both convinced it was valve train / camshaft/chain related ,only clue was very slight decrease in power at mid /high range
we would never have said it was gasket/copper ring but it was , it deffo sounded like a knock/tap
we changed the gaskets on that side and deep joy !

 

With the gasket leaking, was there exhaust coming from the carb? I did check for exhaust leakage at first. I thought that was what it was, until I seen the problem with exhaust coming from the carbs.

 

Got the head off. Valves look fine. But I did find this.








Looks like I'll be getting a new head and piston.

 

Success! I have figured out what it is. The machine shop can fix my head. But it broke a valve guide. And it did the normal mess it does when that happens. I'll have the head back next week. And the gaskets the week after. Just in time before riding season ends here!