Today, after rejetting going back to Dynojets recommendations of 128 main and needle on third notch down, I went on a short ride and about a half mile later, the engine decided to completely die in the middle of the ride the back tire just locked up. I shifted to neutral and tried to turn it over with the electric starter, but nothing was budging. After pushing my bike home, I took a rubber mallet and started tapping on the cylinder sleeve trying to see if the piston had seized. After doing this for a while, the engine turned over again, but only very briefly before locking up again. I then sat there and rocked it back and forth in first gear trying to break the engine loose again. This worked, but again the engine locked up after turning over a couple times. One thing that I noticed when the engine was turning over was it sounded like a 50cc motor turning over, like it had no compression whatsoever. I've been riding the bike no problem at all up until this recent jetting change. In case some of you haven't been following my progress, I have recently completed installing the 351 big bore kit and doing Marcelinos cam shaft mod. The first time through, I had a slight oil leak and didn't torque the engine components down to spec so I went back in and fixed all this up and everything was running perfectly. I took the cover off the side of the engine and unlike before when I changed out to the 351 kit, a little bit of oil came out. The oil was dark and crappy looking; it did not look like it was a week old oil with a new top end. I also checked the sight glass to make sure that I had enough oil in the machine and it was right where it should be.

I have the top end partially apart now, and something has occurred to me. After removing the cam shafts, I noticed that one of the valves is sticking out farther than the rest of them. I tried pushing it back down, but it feels springy. The other valves didn't have this feeling when I tried pushing them down. I took some pictures so you guys could see what it looks like.

Look closely at the top left of this picture and you can see that it sticks out farther than the other valves



Again, bottom left of this picture and you can clearly see that the valve is sticking out farther than the rest of them.



So what happened here? I'm not sure what to do.

 

piston hit the valves?

 

I take it that's not supposed to happen? Which means my timing was probably off, correct?

 

I assume that is the only way a valve can be pushed up into the head more than it is supposed to? I would just take the head off.

 

Yeah, it makes sense. I wonder what would cause this. I'm going to pull the head and have a look.

 

I backed you up the other day little brother, but your gonna have to start thinking for yourself. When a valve hits a piston, that's not supposed to happen.

 

Appreciate it, I did some researching and found that when that happens it's normally due to the timing jumping. I still am clueless as to what would cause this.

 

Regardless of anything else, you need to remove the cylinder and have a look at the piston top. Do that and then report back.

 

Valve spring retainer failure maybe ?

Can you remove the bucket (tappet) and see what the top side of the valve looks like ?

 

Problem with the cam mod perhaps?