85 Honda ATC125M oil leak

[HondaMan17]

So I bought a 125M for 150 bucks. Got her running within 5 minutes. Throttle cable was unhooked. So I’ve replaced battery, relay, solenoid, fuse, cleaned gas tank, air filter, cleaned and adjusted carb. Had her running like a top. BUT I was just out cruising along hit a snow bank that I tried to get over and BAM chain slapped off. Put the chain back on kept riding. Was sitting in neutral and I noticed oil dripping out from behind the sub transmission. But seems to be only be leaking while bike is on. And it leaks about a drop every 5-10 seconds. Can’t really see where exactly it is coming from. Please let me know if anyone has had this issue and what/where the leak is coming from. Thanks

[350for350]

Worst case (in my opinion) is that you cracked the engine case. In that case, you would need to get it repaired. That may include tearing the engine apart and replacing the case or having it welded. Hopefully it's just a seal. You also need to tighten your chain.

[HorseMcHorseman]

Got an 84 200m so it doesn’t have the sub transmission, but i did have an 84 trx200 for a while that did, I would check out one of the sites with a parts diagram like parts house, I assume there is a gasket or seal where the parts are mated that would be replaced if necessary. like 350 said possibly tightening bolts that compress the gasket could help, and hopefully nothing is cracked.

[HondaMan17]

Okay will do, I appreciate the replies. It seems to be coming from in front of the smalll sprocket behind the subtransmission. I tried to get a closer look by pulling wheel off but whoever had it before me rounded the bolts on both wheels. How do you guys suggest to get them off? And obviously replace -Jake

[HorseMcHorseman]

Depending on the space around the bolts you might be able to get vice grips on there and turn them with channel lock pliers or a big adjustable wrench, another option could be cutting a grove into the nut if the hub bolts don’t protrude past the nuts, and using a large flathead screw driver, one with a four sided bar not circular and using a large adjustable wrench to turn the screwdriver, you’re going to want decent leverage. If you post a picture of the rim showing nuts and space around them we’ll have a better idea of what your best bet. I’m sure there are other ways I haven’t thought of. There are sockets and different things specifically for stripped nuts / bolts but I’ve never tried them, maybe someone else has and can speak to their effectiveness or has another idea. I’ve cut groves into stripped phillips screws on cases before and got them out with a flathead screwdriver, and gotten lots of stripped bolts out of things with vice grips

[HondaMan17]

Cool I just got out of work will post pics when I get home. Am going to flip her and see if I can’t find the leak.

[HondaMan17]

simply can not see where the leak is. It’s such a tight spot, I think I’m going to have to remove sub trans. I’m going to check the OEM diagrams and see if any seals are involved like suggested and check my bolts. But that is my what both my wheels look like. I think the vice grip idea may work too windy and mucky out to try today. Am going to be working on it tomorrow so let me know what you think the best approach is

[HorseMcHorseman]

Yes it definitely looks like there’s enough space for vice grips, might have to be the thinner ones though. Good luck

[twomanytoys]

Leaking in front of the small sprocket prolly means 350for350 is right...busted case when you threw the chain.
Gotta open up that area take off any sprocket covers and clean it up real good you will see whats up.

[350for350]

I have another thing that you could try. Take a GOOD QUALITY impact socket that's a little bit smaller than the normal size. Put it on an extension and, using something such as a dead blow , drive the socket onto the nuts. This will do two things,give you clean edges for the socket to bite on plus the vibrations from the driving will help to loosen the nuts slightly if there is any rust holding them on. From my experiences, which don't include a 125, these nuts are 12mm. I'd try a 11mm socket.

[350for350]

Leaking in front of the small sprocket prolly means 350for350 is right...busted case when you threw the chain.
Gotta open up that area take off any sprocket covers and clean it up real good you will see whats up.

Unfortunately, that's the first thing that came to mind when I read thrown chain and new oil leak.

[HondaMan17]

Yeah I did that trick on my 99 Fourtrax differential cap. Worked great but never got the socket off lol still ride with it on there till this day. And ... I really hope I didn’t crack the case. Would poly steel work? (Mixable putty that can withhold temps over 500 degrees F, claims to be strong as steel) I know that’s probably a dumb question I don’t have access to a welder though. New to the site and I really appreciate all the suggestions and input!

[HondaMan17]

Quick steel* sorry

[HorseMcHorseman]

I wouldn’t really recommend it, years ago I got a cheap 125 mx bike only to find out it had jb weld on the case, which was leaking oil. Took it apart and took it to a shop to get welded. Some of the products like quick steel or jb weld might be a temporary fix but they won’t stick to metal with dirt and oil on it, so you’d want to drain the oil and clean the problem area (where the crack is) with something like few drops of dawn soap and a damp rag or paper towel, not a lot of water because you don’t want water going in the case but you still want the outside clean, but again I really wouldn’t recommend it. Obviously more work is well, more work, but the best thing would be take the case apart and find a shop that can weld the cracked section or maybe find a decent priced replacement case section without a crack on ebay, but I’d probably just go with getting it welded. Repair shops will often have a go to welder shop they send jobs to so you could ask around. Hopefully it’s not a crack in the case though.