I relieve the bridge on my FL350R cylinders with a flapper wheel on the air grinder. I tilt the grinder at an angle one way then the other and do this from both ends of the cylinder. This gives me a cross hatching on the bridge. I check the depth by bending a feeler guage and putting it across the center of the bridge. I then put a straight edge across the feeler guage. If the straight edge rocks rocks on the guage, I have not removed enough. I use .004", but the FL350s run hotter because of being air cooled.

 

Is this common on the 86 model ? I have had trouble with ring wear on the exhaust side ever since it was bored . I was told the cylinder was shot and needed replaced because of the ring wear . I check the wiesco piston and it does not have the holes lined up with the exhaust bridge . What do i order for a piston to get these hole as this makes alot of sense to me as i can get 4 motos out of it before low compression . Lastly i have been thinking of changing to a pro-x piston would they have these lube holes ?

 

As was mentioned before, a person can relieve the bridge.
The bridge heats up faster, because it is so thin. As it heats up, it expands, and sticks out into the cylinder causing undue wear.

A good motor builder will relieve this area as part of his bore job.

 

You can drill your own holes in the bridge area of the piston. I don't rember the size drill to use but I think the instructions are included with Weisco pistons(or at least they were) I sold my 250R so it's been awhile since I did mine.

 

Thanks for the help all i will try this it may save me some $$$$$$$$$$$$$

 

Your welcome & good luck

 

I drill my own holes. I drill two .080" holes centered at 3/8" and 5/8" below the lower ring groove. With a bit that small, it will flex and walk around. You need to start it with a centering tool first.

Put the piston on the rod without the rings and lower it on. Put a felt tip marker through the exhaust port and draw a line on each side of the bridge. Pull the piston back off and drill the holes between the lines.

A small amount of mixed fuel will go through these holes from the crank case. The fuel evaporates cooling the bridge and leaving the oil behind.