Which Ring on Top?

Im rebuilding my top end and im trying to figure out which ring goes on top. the brown one or the black one?

Try them in the grooves. I don't think they both fit in both of them.

Try them in the grooves. I don't think they both fit in both of them.

thank you very much...as soon as i read that i noticed that the black one wouldnt even go in the other grove. :lol:

hey

i need alittle bit of help.

my yz450f have about 150 hours.

im going to rebuild the top end and put a new timing chain in a few weeks, just to be safe for the next 2 sessons.:lol:

which top end kit is the best? oem or after market. found a deal on ebay 150 shippped http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=300260925189&ssPageName=ADME:X:RTQ:MOTORS:1123

is there a way to check when piston should be replaced. maybe compression gage.

will you recommend to replace anything alse while im in there .

thanks alot

A leak down test, performed by your local shop, is the best way to determine the condition of the rings. If it passes that, then there's not much reason to do any more with it than the timing chain. Or, you can adopt the philosophy that if you replace the rings now, you won't need to later, when it might not be as convenient.

That's kind of the approach I've taken with my son's bike. He's at boot camp, the head gasket is under suspicion, and it's got about 150 on it, so I'm putting rings in at the same time.

As for the piston, you can measure it, and actually see if it has significant wear. Look at the skirts, inspect the pin bore, and measure the ring side clearance with the new rings. It's all in the manual.

Hone the cylinder:

http://www.thumpertalk.com/forum/showthread.php?p=4380759#post4380759

I just replaced my piston,rings,timing chain,valve springs, and valve seals on my 06 WR450. I was very surprised at how good the condition was on the piston. The motor has about 11,000 miles on it and was still running strong.My timing chain was only stretched about an 1/8 to a 1/4 of an inch.

I think that by keeping the oil fresh and air filters clean is the reason these parts wore so well.

I'm looking forward to the next 11,000.:lol:

I just replaced my piston,rings,timing chain,valve springs, and valve seals on my 06 WR450. I was very surprised at how good the condition was on the piston. The motor has about 11,000 miles on it and was still running strong.My timing chain was only stretched about an 1/8 to a 1/4 of an inch.

I think that by keeping the oil fresh and air filters clean is the reason these parts wore so well.

I'm looking forward to the next 11,000.:lol:

Not bad for a couple of newbies trying to rebuilt their first 4 stroke. Heck we even got it timed correctly the first time (after a quick TT search and found a response from Gray (suprise suprise)).:p

which piston should last longer, oem or after market?

The answer to that question is difficult to give definitively, and it seems to me that it would depend to some degree on how the engine is used, but in general, the OEM piston is very durable. It will probably outlast a Wiseco in most cases, but a CP unit could be a different story.

how much those cp pistons go for?

Got mine for 190$ from ebay. It was more expensive then other brands, but I really wanted to try it out. I bought the one with 13:1 compression.

190 is pretty good for a little bit peace of mind.

thanks again for the help guys .:lol:

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