Next time, i`ll locktite the oil drain...!!


So there it happened, the rear bottom oil drain screw is missing.. so is the engine oil.. I noticed a very noisy engine when i got home, and saw oil drips under the bike after few seconds.. :bonk:

I could have gotten lucky, but i dont take any chances...

Guess i will take out the engine, and try to open it and change out bearings, rings and look for other damages now..

Life sucks sometimes.. :bonk: Allthoug, life was great only seconds before :bonk:

I think locktiting the oil drain plug is a bad idea. Too many chance to goober up the hole. Safety wire if you must but I think a better choice is a properly torqued oil drain bolt with a fiber washer. Also, how do you intend to clean out the threads after you have drained the oil to make the locktite work? There's always a dribble of oil even if it drains for a long time.

Ditto, forget the loctite! Drill the head of the bolt and safety wire it to the frame if you must be sure. :applause:

I'm going to 3rd that. don't use a loctie on your drain plug. use a torque wrench if you must!!!!! or tie wire like Indy says.

I concur, I'm the resident factory Loctite Rep and I'm all for the safety wire route as it relates to the oil drain plug.

Cured Threadlocker might make it's way into some of the small oil passages.

And that would be bad...bad.


I've always drilled & safety wired my drain plugs as well as the oil filter screws. Indy's advice is sound.

Ok, i take that advice..

Ripped off the head, and cylinder now, and found the piston in a bad shape..

The camshafts are ok, and they had plenty of oil film on them..

The piston`s rear side, has heat damage, so the rings are stuck there..

The cylinder has marks after the heat of the piston, but it feels like it`s something stuck in there if you know what i mean.. Seems like the piston metal has melted on the nicalsil cyl or something.. I`ll try to "hone" (is that a word for cylinder "grinding/polishing" in english? :applause: ) the cylinder to see if i get it out..

But a much more important question:

The cranck is a little blue on both sides of the rod. Is this normal?

I can feel a little slack sideways (from left to right, not twisting) but can not say that i feel anything up/down..

Is there hope for not splitting the engine, or is it just a stupid thought not to?



The connecting rod movements and colour are normal.

I've always drilled & safety wired my drain plugs as well as the oil filter screws. Indy's advice is sound.

to do this do you just drill a small hole through the head of the bolt and then safety wire it to where? just want to make sure this doesn't happen to me and burn the piston.


Damn, talk about Yamaha reliability.

YOu do this to a CRF and I'd bet a dollar to donut that it would have been a mortgage payment to fix.

I safety wire the big drain plug to the little drain plug.

i would say if the crank big end isnt "crunchy" or "sloppy" felling you should be fine with just doing the top end stuff. it would be safe to guess with the heat involved up top that you could melt the piston long before the crank is/was damaged.

now is the perfect time for the 490 kin in your SM bike :applause:.

you will need a piston, rings, and cyl any way!!!

The 490 kit was the only big + i saw about this too :applause:

Wondering if i really need a new cyl though.. Guess i`ll try to see if i can polish away the damage..

If the cams were okay and had a good film, my guess is the crank is fine too. The piston takes the brunt of the heat.

Great thread there! Thanx!

I ordered a standard size wiseco piston today, so i will try this out first..

If the engine still makes alot of noise, i will pull it out of the bike, and do a full makeover.. Perhaps i build it up again with a ported head and big bore then.. But for now i`ll just stick with original ccm and my hotcams+ setup from before..

If this goes well, then my cristmas is saved :applause: A full week free from work, without my bike running, could be boooring...

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