Top-end confirmation, YZ450F

Hi, im doing the top-end on my 450 and i wanted to know which procedure i do. A dry setup(no lubrication in the cylinder), or a wet setup(lubrication in the cylinder). Gonna need to know soon, got a race next week and everything is apart for the piston to go in. Thanks in advance.

I don't know why you would do a dry setup in the first place. Oil that cylinder down and after you put the head on and get it torqued down pour lots of oil all over the cam, lifters and springs. Be sure to use a MolyLube type of material on the cams and lifters during assembly.

Use WD 40 in the cylinder when installing your top end. I've heard people say that if you use oil in the cylinder your rings may never seal correctly. WD 40 worked for me.

I've used marvel mystery oil to assemble the cylinder on a 2 stroke, no complaints. Can't see why engine oil wouldn't be OK too. I've heard conflicting reports on the moly assembly lube in bikes with shared engine and transmission oil. Something about the moly and the clutch, I think. :banghead:

I'll second the Marvel's oil based on a claim a very intelligent friend of mine made in that it is ashless when burned (which any oil will be burned in the cylinder, and not all are ashless)....

I've heard people say that if you use oil in the cylinder your rings may never seal correctly.
Myth. Use oil. Lots of oil. Mop it down good, too. Just wipe out the excess above the piston before the head goes on so it doesn't smoke too much when you light it off.

Good lubrication is more important during break-in that it is later on. If your cylinder is finished right, the rings will seat within the first hour of operation. I broke in our 250F this last year on Mobil 1 MX4T, and it hasn't used any oil since I changed out the oil after the first 3 hours.

Myth. Use oil. Lots of oil. Mop it down good, too. Just wipe out the excess above the piston before the head goes on so it doesn't smoke too much when you light it off.

Good lubrication is more important during break-in that it is later on. If your cylinder is finished right, the rings will seat within the first hour of operation. I broke in our 250F this last year on Mobil 1 MX4T, and it hasn't used any oil since I changed out the oil after the first 3 hours.

ok so ill just use the usual semi-synthetic that i put in the bike and make sure not to get any above the piston. I hope it doesnt smoke, never did a 4-stroke topend before, just 2-strokes

Don't worry too much about the oil on top. That will burn off in less than a minute. Just make sure it's not excessively oily before you drop the head on, that's all.

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