Reply To: KG7 Lower Cylinder not firing

[Sam M.]

Mark Quint wrote:

To remove rust, would you recommend removing the cylinder block cover and polishing (with pistons still in and protected) or would I be completely disassembling?

Also, can I replace the top and bottom oil seals without complete disassembly of crankcase?  Seems like yes if I read the service manual and replace the oil seals carefully.

Also I see that the points on the bottom cylinder open only to 0.012 in… not 0.018 in as recommended… need adjustment (and cleaning). That could cause weak spark. I do not see pitting or wear on the points, I think they are OK.

I would put Evaporust in through the sparkplug holes, put the sparkplugs back in to reduce evaporation, and let it sit for several hours, while making sure the rust is not covered by the pistons and that the pistons are covering the ports so the Evaporust doesn’t leak out.  Then, drain the Evaporust out and check with your video scope if the rust is gone.  Repeat if needed.  I would then blast out the dislodged rust particles with carburetor cleaner, which would probably be more effective if you took the cylinder head off.  Maybe you could try to shoot it out the exhaust port(s) if you kept the cylinder head on, but be careful not to wedge it between the pistons and cylinder wall as it could cause damage there when your motor is running.  I bet official published procedures would recommend removing the pistons for an even more thorough cleaning, however for that little amount of rust I think it will be OK not to remove the pistons so long as you don’t let the dislodged rust particles go where you don’t want them.

I don’t know about your oil seals.

In that case I would just reset the points.  No need to wear them away by resurfacing unnecessarily.