Well about a moth ago I was out at Pismo beach at the sand drags racing my buddies one on bored out yz450 and another on his yz426 and I was smoking them on the hole shot but they were taking me on the shift from 1st-2nd then losing no ground after so I decided to slam shift it into second (wfo no clutch click into 2nd) and well this is the result. Luckily I had already bought a WR trans and was planing on doing a large over haul on the bike any ways but to say the least this made it a necessity. Also I was running a Rekluse z-star non pro. When it happened I thought I had broken something in the clutch but after getting it back to the trailer and taking the clutch out. I found the rear wheel was still locked up I realized my weekend ridding was done and my weekend drinking had just begun lol! A little more info on the symptoms on this failure after it fully seized the engine would not turn over at all without trying to spin the rear wheel except for the small amount of slop in the gears. It also ruined my clutch because the z-star actually would try and over come the seizure and get me about 10 feet before it would heat up and drag the engine down and kill it. Also this the second gear cog on the main axle.

Looks like there was a lack of lube.  What transmission oil were you running and how much was in the case?

It seems like TIG welded bead. Did you installed a new main axle?

KMTR: That was the first thing I thought to when I loaded the pictures in the computer. In life though it looks a little different. Also yes my wr trans came with all new/used shafts and this is the shaft where 1st gear is part of the shaft non replaceable

USED YZ426F: 15-40w Diesel oil. After the fact I found out how the oil check bolt method leaves you at about 320ml of oil where it requires 750ml of oil. I used the oil check bolt method of filling since day one of owning the bike (about 6 months) but this is was my first time running in sand so the oil was running much hotter and I’m sure the low level was the cause. Live and learn lol. The good news is it happened right when I was about ready to pull the trigger on installing my wr gears and doing the rb carb mod and eg 295 kit.

The check bolt only works for the Hondas.  That puts 600cc in a 750cc sump.

 1987CR250R, on 09 July 2012 - 09:06 PM, said:

Well good to hear not only yamaha can't figure out where to put a oil level check bolt lol. In all honesty though i'm not to upset it was my excuse to follow threw with my plans any ways. Better now than after all the work i'v done now.

 f150jokerstyle, on 09 July 2012 - 06:40 AM, said:

Your 4-stroke buddies are toast.

 f150jokerstyle, on 09 July 2012 - 06:40 AM, said:

nothing against you but ive warned people several times around here about using that stupid check bolt. they dump oil in until it drips out the bolt but they dont realize they only poured in about half of whats needed. it fills up one case half fast and runs out the bolt hole but the other case half is still empty. takes a while for oil to get to the other side because theres just small holes into the other side.  not knowing any better or bothering to notice the bottle is only partially gone, they think the trans is full and go about their business

 harryhandshake, on 10 July 2012 - 05:26 PM, said:

No hard feelings taken   Unfortunately I really did not frequent TT much until after the fact nor had I ever heard of the problem. Upon research I found multiple references and one thread on the problem in this forum. So it is out there! That is part of the reason why I started this thread so people might see what is at risk if you don't add the correct amount. This is my first 2t, my old 4t if you put all the oil in the manual called for it blew seals so you lived life off the dipstick. So when I saw the check bolt held way less I used familiar thought process and figured o just like my old 4t. Exact opposite come to find out lol.

your saying there was a design flaw in the yamaha crankcase which put the bolt hole in the wrong location therefore only allowing 320cc of oil before it drips out ? i have to say im finding that hard to believe. like i said before, since the check hole is normally in the same crank half and close to to oil fill hole, if you pour in oil its going to quickly fill up that side of the case and come out the check hole because it didnt have enough time to flow into the other side of the transmission case. does this make sense ? given a few minutes the oil has some time to travel to the other case half and the 320ml wouldnt have driped from the check hole. im wondering if your bolt hole is correct but you didnt give it time for oil to get to other parts of the bottom end ? regardless, maybe your check bolt is inaccurate but even if it is accurate, i never recomend using the check bolt for any reason. if you see oil on the ground from a leek or extra smoke from a bad crank seal, its foolish to keep limping the bike around using the check bolt as a oil gauge rather than fixing the problem. dump in 850ml or what ever the engine calls for and call it good. after you dump the old oil, pour in another 850ml and dont even worry about that check hole. some people even put in alittle extra and thats fine

Edited by harryhandshake, 10 July 2012 - 08:36 PM.

From the other threads I read on the topic the bolt hole was flat out in the wrong place from what I understood and shorted you on oil. But I'll tell you what I just recently filled my bike with exactly 750ml which is what it calls for on the side of the engine and factory manual. It has been sitting level for 2 days now so I will pull the check bolt tomorrow and see what comes out. I do understand what you are saying though and it seems like sound logic. But I'll pull the check bolt tomorrow and see regardless. Not sure on where you are coming from on the oil on the ground talk but regardless what your saying seems true to me on that aspect as well?

 harryhandshake, on 10 July 2012 - 08:30 PM, said:

Yes. The hole is mis-located in the crankcase. It may not be exactly 320cc, but using the check bolt to verify oil level in the YZ gearbox will result in less than recommended oil.

Ok test results in. First I started with verifying I had the correct amount of oil in the case. On the side of the clutch cover it says 750cm to the third power. Next in the factory yamaha 2001 yz250n1 service manual it says I quote "Periodic oil change 0.75 L (0.66 lmp qt, 0.79 US qt)" When you convert all of those to ML which is the type of measure I used due to my fill cup, you get 750ML. That is how much I dumped into it about 2-3 days ago has not been touched since. So now that were all on same page I added the correct amount of oil, next step. I used the same fill cup I used to fill it with and pulled the oil check bolt and drained the oil into the cup until the oil had come to a slow but steady stream. Are you ready for this.... It filled my cup up to the 400ML mark which leaves me with 350ML. So I think we can all agree now that after I know the same result was found (with in 30ML) in at least one other thread that yamaha screw the pooch here! So now I say we all band together and file a class action law suit on yamaha asking for money or the latest and greatest including direct injection on the 2014 yz250. LOL yeah right! I hope this puts this one to bed!

Edited by f150jokerstyle, 11 July 2012 - 04:12 PM.

I use the oil check bolt for exactly that, checking the oil. But not the level.
Its nice to know your transmission has (clean) oil in it before heading out into bum-fd no where.

 Vintage Not Pimpage, on 13 July 2012 - 08:05 AM, said:

That is the only possible purpose it can serve with it's location. Unfortunately the manual only list it's sole purpose as checking level. "Oil flows out-->oil level is correct. Oil does not flow out --> Oil level low."