Oil Change

i bought a 1979 xs650,Yamaha, tank was rusted so i clean it out,took the cabs off rebuilt then, put them on bike started right up, but back fired like a lot took them off took a hot air gun heated the intakes up put the carbs back on. that fixed the problem. runs good.took it for a little ride. now the oil change, so i need a 27mm and a lot off luck, and I can clean the filters Right.

Not luck, unless you're unlucky. You can spray the filters with brake cleaner. The big filter sometimes has a tear you'll have to fix with JB Weld. Drain plug washers are easy to get on ebay these days cheap. 1 3/16 or 30mm ID. Let the oil warm up before you remove the plugs. I like to take the rear plug out first, because it's in an area where sludge can accumulate and the gush of oil might wash it out. Careful not to overtighten the big bolt on the small filter or the small bolts on the big filter. There ought to be a better way to measure JB Weld. Too much white and it dries too soft.

every petcock I get from dealers leak, is their a dealer out their that gives a shit about his customers to get them the pet cock for left side xs650 yamaha 1979 that don't leak and turns off and on .

buy a brand new yamaha "valve", the 4 hole rubber gasket, then read the rebuild thread. Only way I know of to get a petcock that doesn't leak. NOS or used petcocks WILL leak, and some of the metal parts in used petcocks are too far gone to ever seal again. Just part of the fun with old motorcycles.

From the sump of "Madness"

Pretty sure this is a MikesXS sump screen, no idea how long it had been in there.
A JB weld repaired stock filter going in.
Kind of related; Decades ago "JB Weld epoxy was used on the Madness RH side cover as part of a remote oil filter plumbing install, The JB weld is holding up fine, only minor flake off, lifting found where it was just smeared thinly on a rough casting.

Yes, that looks like the aftermarket replacement. The "tells" are the perforated sheet metal backing plate behind the screening and the round magnets. That one tore in some odd spots, never saw tears there before. Especially that 1st pic. That spot is nearly as far away from the oil intake hole as you can get. Suction should be the least powerful there.

Nice write up, Hosk. The only thing I didn't see in the directions was to warm the bike up a bit before draining oil.

I recently discovered gas in the oil of my 83. I believe this was from gas leaking past the rings. The petcocks are doing their job and I recently re-jet the mikuni VM 34 (on the bike when I bought it ) to base along with new needle seats (I suspect that was the culprit). With that fixed, it on to the issue of gas that mingled with the oil. I dumped the oil and found that the sump filter is in very good shape. A tiny amount of metal specks on the plug magnets and these bits of plastic (photo below, no doubt cam chain guide)
1. Is this enough debris to warrant replacing the cam chain guide?
2. With fresh filters, gaskets, and oil on hand, what is the next best step? Should I reinstall the existing filters and flush out the case with solvent or fresh oil and then dump and refill with all fresh or replace the cam chain guide first and then move on?
This site has been very helpful so, a great deal of gratitude to all who have contributed.
Thanks

Looks like chain guide. Close it up and add new oil and ride the wheels off.

Yeah the guide tends to shed the thin edges from each side. if you adjust the chain properly and the rubber don't fall off they can go a long time, chain rubbing on aluminum is pretty obvious to the sympathetic ear. Watch for that pretty metal flake swirl look at oil changes. Keep riding.