Jump to content
Sign in to follow this  

....more bottom end issues

Recommended Posts

Just put a fresh top/bottom end in my 08. At about the 1hr mark (3rd moto of the day) it locked up while entering a corner. I knew it didn't stall as it came to an abrubt stop. Kick start wouldn't move.

Last night I pulled the right side cover to get a ratchet on the crank primary gear bolt. It was locked up but broke free and rolls over now. I'm guessing I seized the big end rod bearing; I'm just curious as to why at 1hr after a rebuild.

Some things I checked:

Cam timing was right on

Engine oil was drained through a auto paint strainer - Nothing in there

Oil filter had no trash in it

Plug color appeared to be gray/ashy

Any ideas or thoughts?

Share this post


Link to post
Share on other sites

OEM parts or aftermarket? Possible the bearing wasn't clearenced right? Hard to tell untill you get it apart. Did you use any additive in the oil and plenty of assmbly lube?

Share this post


Link to post
Share on other sites

It was all OEM parts. I lubed all the bearings with engine oil as I was building the motor, with a syringe filled with oil.

Does anyone know if the flywheel side crank end is pressure fed oil, such that internal passages supply the crank bearings and lower con rod bearing with oil, or is the crankcase only lubed with oil squirted from the brass nipple (spray and pray)? I'm wondering if a passage in the ignition cover is blocked (although I cleaned things up before rebuilding). I did notice that that it was pushing the slightest bit of oil past the ignition cover gasket at the cover/case mating surface where the pressurized oil passages meet. this is the galley that feeds the cylinder and goes up to the cyl head.

Share this post


Link to post
Share on other sites

Just to follow up -

I got ambitious and peeled it apart last night. Vertical score marks on the cylinder walls and piston skirt - So I squeeked it. The cylinder scores were basically 360 deg around so it led me to believe it was a ring end gap issue. Atleast it wasn't the bottom end.

Measured my ring end gap: 0.008" which is roughly 0.002" below the lower spec per the manual.

First time in 10 years of building bikes that I didn't measure ring end gap/ piston ring groove OD/ Piston-Bore CL while rebuilding. I was in a hurry trying to slam this thing together to go riding, and it jumped up and bit me.

Lesson learned.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×