When to change piston rings in a yz 85 - 2005 Yamaha yZ 85

SOURCE: Piston rings

If the piston you are using has a pin in the ring grooves then the ends of the ring will be shaped to conform to the round shape of the pin. That will dictate how the rings go on.

If no pin exists, it doesn't matter which side us up.

Standard industry specs call for a 32/1 mix That equals 4 ounces per gallon of gas.

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SOURCE: yz 250 2008 possible 5th gear stripped?

I doubt that any gears are stripped. Believe me you would have known it when it happened at 40mph which is where you would have to be in 5th gear. This is a bent shift fork. The actual gear is fine. The slider gear is not moving far enough to engage with 5th gear. The YZ does tend to have this problem in 5th and 1st. "Dirt rider Magazine " did a story on it. Best to let the shop do the repair as the entire motor gets torn down into about 100 parts.

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SOURCE: 87 yz 125t. bored .30'' over need 56.75mm Piston

yea, for most bikes they only come in .020 increments now. if your looking to freshen up the top end, then youll have to go to a 56.00mm piston. there will be almost no change in displacement or jetting from 55 to 56mm. if your replacing the piston, its best to have your cylinder bored anyways. since the worn cylinder walls may have adverse effects on the new piston rings, and they may wear a bit prematurely. a bore only costs about 30-40 bucks most places, and its cheap insurance. plus you will have the peace of mind knowing that your bore is matched specifically for your piston. I would definitely recommend a fresh bore.

SOURCE: got given a old yz 80 changed piston and rings its

I'll start with the obvious.... have you tried removing the plug, putting a little gas in the cylinder, putting the plug in and wire back on and then kicking it over? If it starts, runs for a couple seconds and dies (burns off the gas you just put in there), it's a fuel or fuel delivery problem. Has the carb been cleaned, the needle and seat checked, the float height checked, air passages cleaned out, etc.? These carbs are famous for getting gummed up after sitting a while. (I have 4 dirtbikes and clean the carbs every spring before firing them up for the first time). Is the oil to fuel mix ratio correct? Too much oil will cause this as well. If it doesn't start with gas poured in the cylinder as mentioned above, check to see how strong of a spark you have and if the plug is gapped correctly. The spark should be bright blue. Hopefully you know how to check this, but if not, take the plug out, put the plug wire back on the plug and lay the electrode end of the plug (spark end) up against the cylinder head with the end of the plug touching metal and kick the kick starter over. You should see a bright blue spark. If it's a weak spark (not bright blue) it's an electrical problem such as a faulty coil. (WARNING: DO NOT HOLD THE PLUG IN PLACE WITH YOUR BARE HAND when kicking it over. You will get zapped good if the coil/spark are ok.) Try these troubleshooting tips and then let us know the result. We'll go from there.

SOURCE: YZ 125 Keeps burnig piston & Ring on Exhaust

only reason would be your running too lean. which causes more heat, which causes pre-gnition and pinging. Also if timing is off you create more pressure which in turn causes more heat