Hi guys, I'm in the process of installing a kustom Kraft 331 bb kit with wossner piston and ring set. The oil control ring and second ring are fine but the top ring when squared in the bore overlaps about 3mm. Is this excessive? I know you can file them back, but that seems too much. Any advice please.

 

If it overlaps at all, that isn't going to work, let alone being excessive.
I'll let the motorheads advise on clearance, if you don't get any help check with a moto shop mech.

 

Hey durielk, got a Moto mechanic on it. He hasn't come across it before. Going to try find the answers on Monday. Looks like a new ring set. Just a bit annoying, I am busting to ride it with the new cubes on board. Cheers.

 

When ever you install a piston you will need to set the gap on the rings, part of the job. I just don't know what the clearance is suppose to be. Bill did mine with the BB piston. You just need to talk to someone that does engines or a motorcycle engine repair manual. I don't have one.

 

For the stock 72mm bore the top ring is supposed to have an end gap of 0.20 - 0.35 mm (0.0079 - 0.014 inch). Wear limit 0.6 mm (0.02 inch). From the '09 service manual.

Bigger bore, bigger end gap.
Arithmetic.

 

Wiseco recommends suggests setting the top ring gap using this formula-(bore size(in inches)) X .0040 Say your bore size is 80mm then 80/25.4(mm/in)=3.15 in. X.004= 0.012 in. end gap Wiseco also suggests setting 2nd ring gap using 0.0045 multiplier. The larger gap on the second ring reduces pressure between the top ring and helps with sealing.
I would be very concerned about the top ring that you have- I think that it isn't the correct one for your bore size. I have never had to remove more than a couple hundredths on an inch to get the gap right.
Try this link- http://www.wiseco.com/PDFs/Manuals/RingEndGap.pdf

 

I've never come across this before either. I have screwed a few auto donks together in my time but I'm very green when it comes to Moto stuff. Just thought it might be how they come and you can knock off the excess albeit excessive. Sounding very much like its the wrong top ring. Lucky me.

 

I would take it to a small automotive engine shop or garage, they should have a ring grinding machine. Explain your problem & try and get them to trim the ring.

 

Don't try to grind it! It's the wrong ring
marc

 

Got a new ring set coming from Kustom Kraft. Mark has been very helpfull. Hope to get it soon.