2003 yz250 BROKEN off drain plug thread section off crank case pics included

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tom9286

Member
Feb 25, 2007
17
0
Without the long story, I have a 2003 YZ250, overtightened the Drain plug and instead of stripping the threads the outside section of the plug hole cracked off of the transfer case. All peices fix together PERFECTly and have a very nice porous mating surface.

First of all, this seems like a crapp design having the whole at a 45 degree angle with half of the threads protruding from the crank case. All bikes i have had in the past have been perpendicular(ive had this bike for 1 week not :(


My options seem to be purely replacing the crank case. Since shops are closed today i would speculate parts + labor on this would be around 500ish? Anyone have a better estimate?

Here is my first plan of attack. If anyone has seen this before or has and pointers PLEASE let me know.

I plan to use JB weld to attempt to patch this!


#1 thoroughly clean area
#2 glue together the two broken seconds. Apply thin second and third coats over the outside around the crack over th enext few days.
#3: glue this section to the main body. Over the next couple weeks apply many coats of jb weld in successively larger areas. I plan to do around 6 thin coats. Maybe one thick one at the end.


#4 Retap the hole.
#5 Use oil resistent gasket sealer on the top half of the threads and lightly screw this in with maybe 1/2 a wrench turn after finger tightening. I plan to use the gasket sealer as a weak form of locktight + sealent. Hopefully this will keep the bolt in place and allow for removal without damaging the hole.

I hope this "patch" job will work as there are no real high pressures in the crankcase. Its basic purpose is a plug.

Wish me luck, if anyone else has experienced this or has any tips or comments or predictions of failure let me know!

seems as if this place hates pictures sorry for this... but just take out all the -'s
w-w-w.-el-m-0-.-c-o-m-/-pics-/bike1.jpg
bike2.jpg
bike3.jpg
bike4.jpg
thats the normal just with domain name elm0 (thats the number 0 at the end)

if anyone knows how to link or post pics let me know ;)
 
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Denny1068

Member
Jan 25, 2007
27
0
that sucks man i did that actually i cracked the case...luckily my dad's friend builds motors for a living and has a massive machine shop we thought it was the threads at first not knowing that it was cracked because it was dirty but he welded it all nice and you cant tell...but when i thought i stripped it he was gonna drill and tap it with a left or opposite threaded bit, so go to a machine shop and ask them about it worked for me, i learned that you cant snug that drain plug too tight the hard way
 
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yzman_bad250

Member
Feb 25, 2007
9
0
done the jb weld on the oil plug it held but it leaked and to change the oil had to flip the bike over :bang:
 
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tom9286

Member
Feb 25, 2007
17
0
hmm thats a good idea.. i think ill jb weld it smother the top of the bolt/around the area with permatex ultra black gasket sealer and just flip the damn thing over ot change the oil.

I think ill only screw it in to finger tight and maybe add kevlar thread to the jbweld outter coats.

Trying to find to way not to spend the 1k to fix it :(
 
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76GMC1500

Uhhh...
Oct 19, 2006
2,142
1
If you don't mind splitting cases. I would buy a thread repair insert that is slightly larger than the hole, drill out the rest of the hole, and use a bigger drain plug bolt if necessary. www.fulltorque.com sells thick walled inserts that may be thick enough to allow you to use the original bolt. You would have to use one of the FFT inserts because of the thicnkess of the cases.
 
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2strokerfun

Member
May 19, 2006
1,500
1
Well, the crankcase half you need sells for about $367.63 or more, depending on where you buy it. Gaskets are another $20-25 or so. Wow, even if you do it yourself and don't change rings, piston or any other part, your looking at $400 or so. I think I'd pull the engine apart and attempt to have a good welder weld it back together. You'll probably still need to clean up the hole and helicoil it after that. Good luck.
 
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tom9286

Member
Feb 25, 2007
17
0
That was my worst fear. Sounds expensive. I have never actually torn apart an entire engine before. I guess this will be a learning experience!

Currently I live in an apartment and tearing apart the entire engine may be a pain, along with the fact that I dont own all the speciality tools required for all the valves piston rings ect and whatever else im missing.

I think i may go to

#1 glue pieces together as originally mentioned
#2 jb weld the bolt in place also for added strength.this should make a tight plug!
#3 well ill have to flip the bike upside down to change oil


When I buy a house in 6 months ill tear it apart and get it done right

What is the tear down time on a project like this? I would expect it to take me 12hours of tear down, 24 on rebuild. And hope I get all the gears, clearances, ect correct hah!

didn't sleep a wink last night worrying about this... i guess ill learn from my mistakes.

Thanks for all the help and ideas. Now I just need to research the difficulties of tearing down to decide if I patch now and tear down later or do it the right way now.
 
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2strokerfun

Member
May 19, 2006
1,500
1
One other option: A really good welder may be able to fix it with the bike flipped over. It's a tricky repair, no matter how you do it. I'd ask for some recommendations for expert aluminum welder, then take him the photos and let him decide if he can do it or not. If not, you can always try the JB weld or another method suggested here.

In answer to the tools question isn't this a two stroke? If so very few specialty tools will be needed. You might need a special flywheel puller socket (about $14 if needed); A case splitter tool (Can use an automotive timing gear puller [$15] and a couple of REALLY long metric bolts you'll likely have to order [$10 or so]; a few larger sockets you probably don't have for clutch removal; C-ring pliers; and a torque wrench. Now, for removing the clutch and maybe the flywheel, it is sooo much easier if you have access to an impact wrench. I use air, but if you don't have a compressor, you may be able to get one of these new battery powered ones for about $100 to $150. If not, you'll need a tool to hold the clutch as you attempt to remove it. I generally just use my fingers or a big hose clamp to compress the rings when installing the piston.
 
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tom9286

Member
Feb 25, 2007
17
0
I will definitely call a really good welder first and ask them about this. Next ill do the JB weld. Finally i will tear it apart, replace the case. I never realized how expensive tools were considering until I moved 1000 miles from my parents I just used all my dads. He was a mechanic at one time and owns every tool known to man. Now the real world hits me!

thanks for all the help ill inform you all how the welding on a fully assebled bike goes. 80W oil shouldn't ignite anyways.. rightttt
 
7

76GMC1500

Uhhh...
Oct 19, 2006
2,142
1
You'll still have to tear it apart to have it welded. Aluminum absorbs oil so there is a long process that has to be done to purge the aluminum of oil before it can be welded. This involves dips in various solvents and acids. If not done, the resulting weld will be porous and leak.
 
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tom9286

Member
Feb 25, 2007
17
0
yzman_bad250 said:
I have 91 cases I dunno if they would be the same but if they are u could have them
Click to expand...

Thanks for the offer!!! ill look into that. I doubt it and know that the 2002 2003 engines are the same but ill look into that.

off the yamaha web site the part #'s are different but hmmm well see what i can scrounge up
 
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tom9286

Member
Feb 25, 2007
17
0
Welp going on 10 months now! Not a drop of oil. Been draining it through the oil check hole. Today i actually tool the bolt off to drain it that way in case "material" was building up inside that wasn't coming out when draining it through the check hole.

Needless to say its a couple hour job of cleaning with acetone, removing all the old gasket sealer, resealing and letting the bike dry while laying it on its side.

Hopefully it still wont leak tonight after the reapplication of gasket sealer. I tried to put alot less on than i origianally had.

In the future i think ill just drain it with the bike upside down out the fill hole and not take the bolt out again.!
 
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stumanarama

Member
Aug 29, 2007
306
0
my friends dads told me the story of how a while back his honda shadow got a cracked case from oing up some stairs, he took it to a good aluminum welder, and the guy strung the bike up from its front wheel, and welded it up no problem. i dont know the details about him treating the aluminum to get rid of all the oil but i do know that it held problem free until he sold it
 

Ol'89r

LIFETIME SPONSOR
Jan 27, 2000
6,958
45
Glad it worked for ya but,,,,,,,,,,I wouldn't venture too far from your truck if I were you. :whoa:

JB Weld is pretty good stuff but it can come off over time. The heating and cooling cycles that an aluminum engine produces can cause the JB Weld to loosen over time and it can fall off in one big piece. I've seen it happen. Especially if oil is leaking and spreading between the JB Weld and the case. You can't even tell if oil is spreading until the whole piece falls off.

A good tig welder can repair your case by welding up the hole and re-drilling and tapping the hole. The case DOES NOT have to be taken apart and dipped like GMC said. The oils can be boiled out of the metal using the heat from the tig torch and ground away using a die grinder. It is very important that the metal be ground down to clean aluminum. The oil should be drained and the residue left inside the cases will not catch fire with the tig torch.

The most important part is making sure the hole is re-drilled straight and is spot faced or milled straight where the drain plug washer seals. Take it to someone with experience in this area.

Where do you live, I may be able to recommend someone.
 
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