Posts
94
Joined
11/24/2019
Location
Lake Stevens, WA, USA
Edited Date/Time
8/26/2022 11:14am
Hi all I need some advice on my 85 sx. I was out riding in oregon on some fast flowy trails pretty much racing my brother in-law I was wide open 3rd and 4th alot the bike felt perfect till it skidded to a stop the rear wheel had locked up it looks like the rear caliper seized some what. That's when I noticed my swing arm covered in oil from the muffler I am running 36 to 1 with maxima super m and 92 non ethanol. I did just replace my the cranks seal but it didn't look bad. The bike also when I start it cold with the choke it revs real high till I blip the throttle a few times. Any advice on where to start would be great. I'll snap a photo after work of the amount of oil on the swing arm
The last 85 that I rebuilt I peened a couple small spots around the seal to prevent
it from moving.
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1) can you pull the expansion chamber and get a pic of the piston through the exhaust port?
2) the bike ever restart once it cooled? Don't start it now but if you already tried did it work? Sound like it does if I read it right but maybe that was pre-seize.
3) can you check the coolant level please? Is it low, gone?
4) do an oil change and drain it into a ratio right or whatever and compare the oil level to whats suppose to be in there in cc. If you didn't change it or it was previous owner just see if it's low
5) how was your spooge before this? Considering the blown exhaust seal maybe its exaggerated a bit.
I almost think that we're being thrown off by the torn exhaust connection and it just looks worse because its an 85 and they tend to get really dirty when not rung out. I don't know how much throttle you use on flowing trails, could it be exaggerated because of low throttle input over a long ride? You dot have to change the oil you can reuse it but I would at least measure it. Up to you if you want to actually replace it but I'm always a fan of if you took it out you're already more than half way there. The right side won't cause it to go lean, that was just to see if the spooge was a combination of engine and trans oil.
The plug is kind of whitish to me. It could be that it is lean on top where you were really on it, but the spooge is kind of the old build up you've been blowing out which would help explain why thy it looks lean and rich at the same time. Can you pull the left side and see if there is oil or wetness behind the stator? Are you skilled enough to make a pressure tester (its not bad just some pvc, a gage and a bung for the exhaust. You might have a leaking left crank as stated but I'd expect more issues than just a little rev up when cold that goes away and does not return. Can you verify your jetting and float level and make sure the petcock filter in the tank is not plugged up and causing fuel delivery issues? Maybe it slow leaned out as you were on the main a lot vs normal?
People always think a leaky right-side crank seal will only suck oil.. and that just ain't true. Take a look at most bikes where the oil level screw is relative to where the Primary gear and right seal are. Many times the seal is above the level of the oil and can easily suck air, oil, or either intermittently. Especially once it has sucked the oil level down even farther !
I've seen this quite a few times on YZ250's. The first indication of a leaky right seal was the bike getting super snappy from running lean.
One way to test, if you're doing a leak down test and losing pressure, put the trans vent hose into a jar of water and see if bubbles come out.
Pit Row
That fluid looks a little odd in texture but its super easy to get fooled through a pic. I've actually never tried this on a 2 stroke and I'm not sure if it would work but it makes sense, we're you able to smell any fuel in the clutch/trans oil? On a 4 stroke would indicate bad rings but maybe its possible to have some seep through the crank seal on a 2 stroke on the down stroke and just very slow weep in there? Idk, the leak down would be best tbh lol. Would rule out a lot.
Its just nothing in your pics screams at me, I really thought it should be super obvious. Being an auto tech I tend to just pull things apart but I hate to suggest that because not everyone wants to do that, and sometimes you do all the checks and find nothing and you pissed someone off lol. Let me see if I can find my tester. Its super basic and easy to build and then pressurize with a bike pump or similar. It would definitely be nice to rule out an air leak. The 2 strokes are so sensitive to that.
Ahh man yea I hear you on the time crunch. Let us know what you find when you do.
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