[Ed G.]

I just rebuilt everything from the case up, New Cylinder, New Head, New piston and rings, lapped the valves and used all OEM Honda parts. Valves were adjusted to the book specs. All new gaskets. I can not figure out why this thing is still smoking badly. Can anyone help me with this issue, it would be very much appreciated. Thank you

 

[Ed G.]

I have a 2007 400ex that I completely rebuilt the top end, New cylinder piston and rings, New head and all new gaskets all OEM Honda parts. Smokes badly when giving it throttle. Can anyone help me with this issue?

 

[Here 2 help]

Welcome to the forum

The first thing that comes to mind is the valve seals and the condition of the valve stems of the old valves.

If it's not a valve issue, then were the rings installed correctly? Was the oil rail expander ring installed without the ends overlapped and was the compressions rings installed with the marked side up? Were the rings installed with the gaps positioned appx 120* apart?

Finally, what break-in procedure was used and what kind of oil was used during break-in?

 

[Ed G.]

Welcome to the forum

The first thing that comes to mind is the valve seals and the condition of the valve stems of the old valves.

If it's not a valve issue, then were the rings installed correctly? Was the oil rail expander ring installed without the ends overlapped and was the compressions rings installed with the marked side up? Were the rings installed with the gaps positioned appx 120* apart?

Finally, what break-in procedure was used and what kind of oil was used during break-in?

Thanks for responding, First the valve seals are new, but I used the old valves. I did take it back apart and the piston had a lot of oil on top when I pulled the head off. I am going to recheck the piston rings to make sure they are right, I believe they were but it never hurts to recheck while it is tore down. I will post the results tomorrow. Thanks again for your response.

 

[davidhosmer65]

Welcome to the forum

The first thing that comes to mind is the valve seals and the condition of the valve stems of the old valves.

If it's not a valve issue, then were the rings installed correctly? Was the oil rail expander ring installed without the ends overlapped and was the compressions rings installed with the marked side up? Were the rings installed with the gaps positioned appx 120* apart?

Finally, what break-in procedure was used and what kind of oil was used during break-in?

 

[Ed G.]

Well, I fixed the problem. I'm not exactly sure which issue it was, but I put all new Kimble White valves in the head and lapped them. I also did a leak test on them and not a bit of leakage. The second thing was the rings, I went to Wisco. Website and checked the placement of the rings specially the oil ring, they were not in the place that Wisco recommended so I put them were they should be and I also forgot the two alignment pins between the cylinder and the head. Now it runs great and is not a mosquito repeller lol. No smoke. Thank you for the response, I wrote all of this so that hopefully if someone else has this problem it will be a reference for them. Thanks again.