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My crankcase vent is puking oil out of it. It is a large amount of oil, not just a small drop or two, its getting shoved out, both when kicking the bike over, and when it's running. I have new head gaskets, and new rings. It is not overfilled, I filled in the exact amount required, and if anything it's slightly underfilled because of how much has been shoved out. It has been doing it before and after the new rings. The bike feels strong, and it doesn't feel like it's losing power in the form of lost compression. The valves are timed and shimmed. What could be causing the problem? Thanks. Could it be something with an oil screen being clogged causing oil to not flow up into the top end like it should, so it's staying in the crankcase?

I dropped my 2019 DRZ-400S and the Crankcase is leaking, it was punctured by the shifter and oil leaked all out. Do I need to get a whole new crankcase or can I just JB Weld it and refill with oil and ride home? I had to leave the moto far from my home and either need to fix it asap with jbweld/oil or tow it home and order parts... which would cost me too much Please help me asap, this is my daily commuter and its costing me a fortune to rideshare back and forth to work. Always lurked around this Awesome forum but Joined today for my question. thank you guys in advance!!

im trying to replace my clutch plates and my crank case cover will not come off its stuck above the oil filter the whole case is open expect above the oil filter. I've tried hammering around the case I hammered the metal studs around the case to slowly open it but the one stud broke don't want to break the case I need help I want to ride!!!

I'm starting to rebuild the engine and crank of my XR400R, cracked open the case a few days ago and noticed lots of metal shards throughout the bottom end. Clutch basket has massive piece that has come off, broken in pieces, and become stuck under the oil screen. Has anyone come across this issue with an XR, and know of why it may have happened? There's still metal throughout the crankcase, so if anyone has techniques for cleaning it out that's important too.

What other parts of an engine do I need to build a WR400F or a YZ426F besides the crankcase halves. A list preferably.

Hey, I'm looking for the right crankcase for my 2003 cr125, willing to pay the price since I know they are hard to find. Thanks.

I have a 2005 kx250f. When ever I kick the bike over a significant amount of oil gets shoved out of the crankcase breather vent tube. And when the bike gets started up and is running like normal, a significant amount gets sprayed everywhere on the bike and the ground. The bike is not overfilled with oil. I know that some oil is normal, however this is a significant amount, and it loses oil extremely quickly. Anyone know the cause?

Hello All This is my first post. I am very much into my bikes but not on a racing level or anything. Lots of practice days... random outings in the woods... Weekend warrior type stuff . feel free to skip to the very last sentance for my actual question as to some of you guys the in between bits might just be waffle. Also, i have searched for an answer to this with some limited result. So... the big end bearing went while i was doing a poxy rolling burnout, or it was already well gone but this is what finished it off. I have already replaced the crank with one that has a new Conrod and all the trimmings (big end bearing). Going back in time now, when i was stripping the engine i did the clutch side first including the primary gear and whatnot, then when going around to the flyweel side i pulled on the flywheel and was stunned when the entire crank shifted. There is no up or down / wobble movement in the crank but it very easily shifts side to side by about half an inch, now i dont know if this was the case BEFORE removing the primary gear and all that stuff but i am baffled. As it stands, i have the new crank in and the crankcases closed back up and bolted shut with nothing else installed, just crank and crankcases... it still shifts side to side, another note is that it literally just falls into the bearing, as in there was no need to pull it into the bearing, heat up the case, freeze the bearing.. nothing... new crank came, i pretty much chucked it at the right case and it slid rite in to its seat. nice and snug... but slips in easy. To me this is very unusual, cranks normally need to be set into the bearing in one way or another so my question is: Is it normal for the crank in these bikes to have sideways play WHEN the primary gear is off of the motor? Thanks guys.

Hi all, I'm posting this about my 2008 WR250F... It's my baby and I've maintained it impeccably. I'm at about the 200 engine hours mark now. I've been riding single track trails for years now and we ride some pretty gnarly stuff. I recently replaced my Flatland aluminum skid plate with a Hyde one, and I think that's where my mistake started, but anyway.... While riding a nasty rock trail (first ride with the Hyde...), I got some air and landed on the skid plate on a fairly flat rock. To me it didn't feel like it hit that hard, but it appears that the impact was hard enough to cause my crankcase to crack (hairline), right above/behind the lower left motor mount, the welded one. I noticed it due to finding small oil drops in my skid plate. I performed a (temporary) JB Weld repair as I wanted to race the Corduroy Enduro and successfully did last weekend. To me the only thing the JB weld could potentially ever do is prevent oil from seeping out. Anyway although the repair still appears intact, oil is still leaking out. The crack is at a brutal spot with behind the engine mount so JB welding it correctly with the engine in place was near impossible. If you're still reading this, I am looking for input from people who have actually performed the task of splitting the cases and potentially replacing the crankcase. I don't really want to sell the bike as is (with full disclosure obviously), because I want to make this bike whole again and ride it 1-2 more years before I likely jump onto a new YZ250FX or WR250F. I think I can get the cases for about 700$ CAD, but what I am looking for is: 1) Just a rough guess, how many extra parts would a person need (seals, orings, bearings, etc), and approximate cost? 250$? 800$? I don't need a detailed list, I can pull that together, I'm just trying to get a rough feel. 2) Any suggestions on where to buy these parts? My local dealer can't give a super price on a case so I'm open to options.... I usually buy from the dealer but for an order this huge I'm willing to shop. Maybe from somewhere in the US that does fair shipping. 3) I know Bombardier offers this for their stuff, but does Yamaha perform these types of repairs/replacements directly? Like factory? 4) Any other opinions on the matter? I don't just trust very many (any?) mechanics and am very detail oriented, so if I do decide to have this work done I would likely do it myself, very slowly and carefully. Let me know, thanks! Luc

Hey guys, First post on here, so of course its because I got myelf into a situation. I recently purchased a 2002 yz250 and long story short the kickstart shaft broke. In doing so it somehow cracked the right side of the crankcase, so I need a new right side crankcase. The problem is there are none on any site used and a brand new one is about 600. I found a 2001 right side crankcase and Im wondering if I can use it with the rest of the engine. I read on another post that the only difference between the 01 and 02 motors are the swingarm bolt diameter, and that the 01 can be bored out to fit the 02. If thats true then I think I can, but I would like some other input. Can I use the a 99 - 01 case or should I bite the bullet for an oem 02 case

So I have a dilemma I broke my right crankshaft bearing seat and I’m wondering if I can buy only the right case or HAVE to buy the left and right set

How’s it going guys. I own a 2003 Yamaha yz250 2 stroke and I am in the process of replacing my right side crank case gasket but I have some concerns. I am new to working on bikes so I want to make sure I don’t mess anything up. I noticed that in the process of removing my case cover I will likely need to replace my power valve seal. Upon further research I read that some people have the issue of having difficulties when putting the case cover back because the linkage in the power valve doesn’t align correctly. Do you guys have any tips on how to move along with this process and making it an easier job. The last thing I want is to cause another problem while trying to solve an existing one. I appreciate the help.

So I have a 2009 YZ250, water went through the whole bottom end shortly after 2nd hand buy so tore down cases, stock cases were a bit beat up in places so bought some 2nd hand 2007 or 2006 crank cases, not sure. Engine is nearly back together and i went to fill up with 80-90 and noticed i was missing a cover/plate on the L/H side that goes over the shift drum (Just below the output sprocket). I looked at my old case and there is no cover its just built into the crank case. After searching schematics and blog posts for the past hour and a half I've turned to the knowledge of you lot! What on earth is this cover and where can I find it? kind of annoyed i hadn't picked up on it earlier. I have a picture of my stock case and the cover missing on my "new cases"