Tight spot turning the crank

This is #1 piston when I ran it out of oil in 13. STUPID. You can see most of the wear is on the right side facing the journal with the broken pin. I'm still running the others. They were undamaged. I didn't realize how bad the valve guide seals really were. I was planning to order a new sight glass and the idiot light was undependable. I knew better and wound up cleaning the old one with carb spray and Q tips. It's still in use. I try to stay on top of things now.
Steve

Man, you got your money's worth out of that one.

I few years back I was riding off-road in the Rockies with some buddies of mine. One of them with a Honda XR600R made sure he changed the oil before the trip. Sure enough he didn't tighten the drain plug. We we're pretty deep in the mountains when the plug came out, and he didn't realize until it powered down and seized. It was a tough trek towing him back with a rope. After we got back to the cabin and the engine cooled down, replaced the plug and filled it with oil, it kicked over and ran fine. No noise or smoke. XR engines are as close to bulletproof as you're gonna get. But of course he sold it as soon as he got home.

I rode it like that until the 1015 barres came. Had to use the stock pistons and rings that came with them. A year later I had a new piston and did a valve job. These bikes are tough.
Steve

Guess I jumped the gun. Been spinning the crank and still feel a slight tight spot. It's random, not any particular number of turns. I put a dial inch pound torque wrench on it and the tight spot is only 5 or 6 inch pounds.

I'm getting a straight edge to check the line bore.

It's either the bore is off, a bad bearing I can't detect otherwise, or maybe just the .0025" run out at the center of the crank. The runout is within specs but new is closer to 0. I'm sure most people wouldn't have noticed it. Maybe I'm overanalyzing.

I spoke with Stan at grc cranks and he suggested swapping case and/or crank and see which fixes it. Wish I Had a few laying around.

Is the crank well lubed while spinning?
Steve

VTEC wrote: Maybe I'm overanalyzing.

Maybe… but I can tell you that I have the same problem, it would keep me up thinking about it.
It would probably run many miles maybe vibrate a touch more but who knows . I am rebuilding a old dirt bike right know and I am trying really hard not to get to technical because like you I am compulsive , it really sucks.

Have someone else put it together then you can blame them :laugh:

Did you ask Stan if he would run it???

VTEC wrote: Guess I jumped the gun. Been spinning the crank and still feel a slight tight spot. It's random, not any particular number of turns. I put a dial inch pound torque wrench on it and the tight spot is only 5 or 6 inch pounds.

I'm getting a straight edge to check the line bore.

It's either the bore is off, a bad bearing I can't detect otherwise, or maybe just the .0025" run out at the center of the crank. The runout is within specs but new is closer to 0. I'm sure most people wouldn't have noticed it. Maybe I'm overanalyzing.

I spoke with Stan at grc cranks and he suggested swapping case and/or crank and see which fixes it. Wish I Had a few laying around.

I'll stand corrected but I can't see a crank or any major item out of alignment having a random tight spot, my crank was badly out when it twisted and it still spun freely, sounds more like a bearing nipping up once in a while. The other thing to consider is a cam chain, if it is not new or the link (if it is riveted) is too tight it might bind once in a while.

"I'll stand corrected but I can't see a crank or any major item out of alignment having a random tight spot, my crank was badly out when it twisted and it still spun freely, sounds more like a bearing nipping up once in a while. The other thing to consider is a cam chain, if it is not new or the link (if it is riveted) is too tight it might bind once in a while."

Chain is off, crank only. This crank spun freely in my previous case because the twisted crank enlarged the journals so the bearings weren't held tight.

SWest wrote: Is the crank well lubed while spinning?
Steve

Yep. poured oil into the oil switch housing hole to lube and confirm oil at all bearings.

Man, It's only 5 inch/lbs. I bet most would have spun it and said it was fine. Hope I'm not chasing ghosts.

Spinning it fast you feel nothing, just slowly by hand.

If it were me I'd put it together and ride the piss out of it.:woohoo:
Steve

Torqued the case and checked line bore. Couldn't get a .0015" blade under anywhere. Ordered another eBay crank to test. After all this work I just can't put it together knowing something's not right.