2000 Yam WR400F

Hi Folks,

New here as im a bit stuck...

Im not the most mechanically minded so could do with some help if poss. I have a 2000 WR400F which leaks oil, about 10 or so drips a day.

It is coming from a small nut at the very bottom flat surface of the frame, down on the what looks like a protector of somesort. The nut is only about 10mil and there are 4 of them but only one leaks.

The thread on the nut has gone meaning it wont tighten fully. I dont know if that is the oil resoivoir or if there is a leak further up and its dripping down to there and thats simply the lowest point its coming out?

Anyhelp would be appreciated as this is now my winter bike! :banghead:



A picture would help:thumbsup:

as soon as i get home i will get one up.



as you can see, the bolt is just under a protective cover, it is the most right bolt in this photo.



Closer view



Closer view, its the bolt at the top of the pic (can see the oil on it)

any help appreciated.

Cheers Kyle

Edited by kyleiom

Refresh my memory, is there a crush washer for that bolt?

im not too sure?

All i can see is that it keeps going round when tightened so some thread must have broke.

The main help would be to know if there is a leak further up somewhere and that it the only point where its dropping out or if there is a resoivoir there and the simple fix is to tighten the nut?

It looks like your oil drain plug is leaking. If it keeps turning the threads are pulled and it needs to be repaired. I don't know if there is enough room to do a heli coil.

May have to re-tap it going one size up. Shouldn't be an issue as long as you can find crush washers to match the new bolt. And a torque wrench is your friend.

ok, if you don't know what that bolt is for, I wonder....how long have yo owned the bike and how many hours does it have on it?

Reason I'm asking is that bolt needs to come out about every 5 to 10 hours of ride time since it's one of your oil drain bolts. (yes there are more than one) and if you have never taken it out, I feel very sorry for your poor motor.

If it spins, you've stripped the threads in the case - yes, it can be tapped and heli coiled (mine has been for as long as i've owned the bike) - you might even get a plug one size bigger and can then skip the heli coil.

When you fix it, just be careful you don't overtorque it when doing oil changes.

The washer on mine is nylon and it seems to work fine.

remove those 4 10mm nuts the sump guard will then drop down away from the frame and you can get a good look at the sump and sump bolt

thanks for the replies, ive only just got the bike and didnt notice the drip at the time. I will have a skeet this afternoon and see what i can do.

Is the idea with a bigger bolt just to fit it really tightly?


you can also try some plumbers tape around the threads of the bolt,and then tighten it back into the sump,i have used this method on a cr250 with good results

Take the skid plate off the bottom of the engine, so you can look to see exactly where the leak is coming from. It should be your oil drain bolt or you have something major going on, but I'm sure it's your drain bolt. You need to have a brass washer on this bolt to seal in the oil drain hole.. Many people sell aftermarket drain plug with larger nuts on them, so you don't strip them easy and they have a magnet on them that will catch large pieces of metal that are floating in your oil.. Get new bolts with the washer and you should be good to go. I would recommend synthetic oil in the bike as well, so just read your manual and it will tell you how to change the oil.

Be careful - you never want ANYTHING to bolt in "real tight" - your case is aluminum and therefore VERY soft.

The idea of an oversized bolt is this:

you tap the hole bigger to accomodate the appropriately oversized bolt and it should fit snug with the right amount of torque as the old smaller bolt.

DO NOT Try to squeeze a bigger bolt into the existing hole, it'll end in an expensive disaster.

The way a heli coil works is the hole is tapped out and a coil is inserted to bring the thread size back down to the original bolt's thread size.

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