stripping out your oil drain bolts.

has anyone done this???? yesterday when I was changing the oil I torqued both the crankcase and fram oil bolts to spec plus just a bit more for good luck. a bit being less than 1/4 turn. they almost felt like they stripped out. how easy is it to strip these bolts out???



Good stuff. Great to hear that someone else uses a torque wrench to install their drain bolts. Ive heard of a few stripped threads in these bikes and i think its pretty easy to strip them if your not careful.

I'm definitely not an expert wrench, but from my experience, if you felt any amount of "give" after the bolts came up to torque spec then you have over stressed something. I've over torqued a few of the smaller 6mm and experienced that feeling that something gave out. Fortunately it turned out to be the bolts and they were easily replaced. On inspecting the threads on the bolt, I could see that they had stretched very noticebly.

As far as using torque wrenches, I consider them to be mandatory on every fastener on my bike. It's interesting that the natural tendency is to give it a bit extra for good measure. When using the torque wrench I very often "feel" like the wrench gave up too early. But, I've disciplined myself to trust the torque wrench (I make sure I'm using a quality wrench designed for the needed torque range, of course). I've heard a lot of stories of problems from over torqued bolts and even some about neglecting to put a wrench on bolts that can vibrate themselves loose. I even had problems from using a torque wrench that was too big. But I've never heard one of these sad stories start out like "I torqued the bolt properly to spec..."

Just my $0.02.

[This message has been edited by neWRiver (edited October 02, 2001).]

I don't torque those drain bolts, just use a 3/8" rachet and get them snug. They are easy to get too tight. I mean they're plugs, not fasteners. I have never seen a drain plug that vibrated out, ever.

I only use Proto torque wrenches, I have a really bad habit of reefing down bolts if I dont use a wrench. I am concerned that I may have wrecked the case on my bike....DAMNIT I hate being dumb!!!!!!!

What's a 'Proto' torque wrench? I was about to buy a Snap On inch lbs wrench yesterday until I saw the price - $199.00! I still may buy it. A

proto is a brand of torque wrench, high quality, pro grade, about $300 per wrench. really nice, as good or better than Snap-On

All I can say is "easy on the spinach" Popeye.

Also...invest (and use) in a good torque wrench. I only use the TW on the ones where I feel its necessary (eg cam housing, suspension pinch bolts), otherwise just by 'feel'. Never a problem.


The Missile

'99 WR400F

Airbox Lid - gone

Throttle Stop - shorty!

Plastics/Tank/Seat - One Industries

Street Legal


Never seen a drain plug vibrate out? Well that's exactly what happened to me a couple of weeks back. Did a whole enduro one week, then started an MX the next (no oil changes in between) and it came out in practice. Expensive!!


If you look up into the case from the drain hole you will see that yamaha has put a porthole/slot in the threads so all of the oil drains out.

This means less thread for the bolt to achieve purchase.

I learned the hard way.

tell me about the hard way.... I am very curious as to how it was repaired.




This is very embarrassing for me, but i must admit that i have also been guilty of this.My excuse was i must have been changing my oil too often.Seriously dont be too hard on yourselve,if you look up tht drain hole you will see that it is slotted to allow you to drain every drop of oil out therefore it is a lot easier to strip if you are a bit heavy fisted.Take you bike to a proficent engineering shop and get them to fit a helicoil. It is very important to get it aligned perfectually otherwise the bung will not seal properly.Also get them to use plenty of oil to catch the swarth and also flush any other swarth out by squirting some engine oil up the drain hole while the bike is vertical. Make sure you go to a descent shop as i know of one poor chap where they tried to tap out the drainhole to fit a larger bolt and cracked the case.(too bigger tap)Mine was done over a year ago with no problems.I also drilled a hole (about 2 mm)through the bung and saftey wired the bung to the frame.This way you only have to just nip it up and be confident it wont come undone

Cheers Ross at NZ

99WR400 Yz tank and seat,ohlins steering damper,terrycable hotstart.14/52 gearing


I am a machinist and a mechanic so the experience of stripping my drain bolt was very humbling.

I used a time-sert to repair my misdeed.

If you are in the bay area I have the kit and inserts to do the drain thread repair.

Just email me.

Oh yea, use a thin washer with t5he aftermarket magnetic bolt.

SFO, I appreciate the help. I live in Minnesota, However, my brother-in-law and riding buddy is a machinist. He about kicked my ass when I told him that I thought I stripped my bolt out. anyway, do you have anymore info on that setup you are talking about. the in-law figures we could simply drill it out, and then tap a larger bolt into the sucker. I really dont know if it is stripped out though, it has been holding for a couple of weeks with no oil leaks or anything. It may just be a figment of my imagination.

thanks in advance,


[This message has been edited by Ronin (edited October 08, 2001).]

Time-serts are a solid insert rework not a coil, like heli-coil.

They have a website.

It is an expensive (90$) kit, but once you only have to buy it once and murphies law has it that you will never need it again...

I have not stripped mine, but my crankcase drain bolt became stuck ( seized). I evidently overtightened.... In the process of getting off... I used a chisel, struck the shoulder of the bolt and it popped loose. threads were fine, but head of bolt was toast...FYI... Your local Honda Dealer has a replacement part that will fit this drain... They offer a 17mm bolt with a larger head, this does not mean more torque, but instead of using a 12mm 6 pt socket to remove the old bolt, the Honda bolt is 17mm and gives you more area to remove.. just my 2cents.


98 WR400

Keep in mind the manual says to replace the copper washers on found on most drain bolts. I believe it's because the soft material compresses when the bolt is tightened. Reusing the old washer does not allow for any compression, therfore transferring all the stress to the threads. Also tightening by "feel" will not be consistant with old or new washers. It's not a 5/8 bolt on the oilpan of that old chevy!!!!


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