When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hey everyone I cant seem to find any answers to my problem, hoping for some help. I have a 2004 Yamaha Beartracker 250. I have an issue where my plug (don’t know name) on the middle top back of gear case where the transmission halves merge was leaking. I was actually able to push it down but it comes back up from presssure when engine cranked. The snap ring that holds the plug doesnt look like original but i put an O ring under it to hold pressure and it literally blew the whole plug off from pressure. My question is: is this plug suppose to have a lot of pressure under it like this? And what is the purpose of this plug and what is directly under it to cause so much pressure? The manual or any parts diagram doesnt acknowledge this plug or the snap ring holding it so im real puzzled at all this. I can see oil when plug came out and the oil level slowly goes back down into engine when not running. My PVC valve is hooked up and patent as should be and my gear box vent and hose is hooked up and just freely open to air. No oil comes out of any of the other hoses and this oil leak/ pressure problem has happened with low oil and when engine full of oil. Any help with this is greatly appreciated! Thanks guys! Pictures of plug attached.
Checking to see what I can find on this for you. I did come across a owner manual you should be able to download for free. Not sure if it's a 2004 model version, but pretty sure a lot of it is the same. I'll try to confirm the year on the manual while I'm checking.
thank you. I have looked through all the manuals pretty thoroughly and i can’t find mention of this plug but it’s possible it went overlooked. Your help is appreciated.
Searching crankcase plug, I see a few things. Some look threaded, some are just plugs. From the looks of this picture of the crankcase, it's a metal plug with a c-clip.
Your second picture shows a big fat breather tube from the cam chain cover, and a smaller breather from just behind the plug you wrote about. Both these breathers take the pressure built up as the piston descends, and blows it into the airbox. Any blockage results in higher pressure in the crankcase, so if the gearbox and crankcase run in the same oil, pressure will build up in both crankcase and gearbox. The breathers have difficulties in shifting 250cc of air out and in, every rev of the crank anyway, so there is a bit of pressure in the crankcase.
10-01-2018, 09:37 AM
Yamaha Beartracker Gear Case Plug Leak
