splitting the case
Posted August 12, 2008 - 03:25 PM
-The story- for everybody who is wondering why I have to replace my case
I got this bike about a month ago. The day after I got it I went to change the oil and when I went to unscrew the drain plug I noticed it was held on by JB weld. I started to unscew it and all the jb weld around the bolt fell off, leaving about half of where the bolt threading in gone. I called the owner, he said he had no idea, wether he did or not is beside the point because he offered me $500 back to fix the problem (I now have the cash) So my first though was a welder, I got someone to do it but it didn't work out so well. So he didn't charge me anything but a couple bucks for his time (he did try to weld it). So now I've decided to replace the case, I'm sure there are other ways to "rig" it but I'm the kind of person that likes it to be done right (so I don't have to worry about it anymore)
So I'm just looking for opinions/advise on the matter of me or a dealer replacing the case.
Posted August 12, 2008 - 03:28 PM
Posted August 12, 2008 - 04:00 PM
Posted August 12, 2008 - 05:14 PM
Posted August 12, 2008 - 06:13 PM
But if you could split the cases on a 2 stroke (which means you're a pretty smart kid) you can do it on a 4 stroke.
You could strip the cases and bring them over to the dealer and have hime crack them with their case splitter.
BTW most kids your age can't even pick their nose by themselves much less attempt what you are going to. I salute you Jr.
Posted August 13, 2008 - 03:22 AM
I think (depending on how bad the stipped bolt is) adding a heli coil to it will fix your problem - I just had my cases split recently due to a bearing failure and noticed that my drain plug was heli coiled and I have never noticed any issues with it.
You won't need a case splitter, my cases cam apart so easy it's child's play.
There really is no difference when it comes to the internals of a 2 vs 4 stroke other than the valves and timing chain, but that's minor.
The only tool you will need is a flywheel puller and you can just modify a cheapo puller to fit - also child's play.
For replacing the cases you need to consider some things:
You definitely will NOT be moving the bearings from old to new without damaging them, so you need 8 bearings to go along with the case, if you go OEM, you will drop 200-250 bucks. If you can get them directly from a bearing distributor through x-referencing them (good luck), you might save 50-60%.
You will need a gasket/seal kit - I wouldn't be moving old seals over to the new cases, I might keep them as emergency spares, but if I'm doing something this big - I'll go new - so add another 100 for a full seal/gasket kit (TT Store Moose racing).
I would also replace the timing chain (30).
Now since you have it apart, it might be a good idea to check your valves (likely won't need replacing), reshim if required and refresh the cylinder/piston, so you may be into another 100-150 for a new piston, rings and some shims.
While you're in there looking, you might also notice that some of your gears could use refreshing since it's a 10 year old bike, at about 40 a pop, that'll add up fast too.
Then there will be incidentals such as busted bolts - I had a few break way before their specified torque - likely just due to age and use.
Anyways, just so you know, when I lost the 25 dollar bearing, I rebuilt my bottom end and after getting all the bearings, gasket/seal kit, shims, 2 gears, a tranny shaft (50), rings, cylinder honing, and incidentals I spent 600 on my bike doing it myself, and that was WITHOUT cases.
So looking at the above list, it certainly makes a heli coil look like a wonderful alternative.
Posted August 13, 2008 - 05:58 AM
Posted August 13, 2008 - 06:40 AM
Posted August 13, 2008 - 08:22 AM
Posted August 13, 2008 - 08:44 AM
Posted August 13, 2008 - 10:42 AM
Posted August 13, 2008 - 11:08 AM
Posted August 13, 2008 - 11:16 AM
JB weld and the ilk are fine for emergencies. When you do a repair, there is a right way and a wrong way. A klugey fix may 'work' but often, they become more of a problem later on.
HeliCoils are great. The threads you end up with are stronger than those before the HeliCoil. In aircraft, nearly all threaded holes in soft alloys like aluminum are automatically HeliCoiled for this very reason. But on a bike engine case, you do not need stronger threads, you need to not over tighten the bolt. In your engine, the threads did not pull out, the case cracked. This is because the bolt size is capable of whitstanding more compressive forces that the alloy can. Something had to give, hence the crack.
Drain bolts are like spark plugs. With a proper washer/gasket, they are seated and then tightened about 1/4 turn more (about 7 ftlbs.). If the washer/gasket is a compressible one, the flat side should go towards the case. This prevents the 'wedge effect' of the washer from placing addition side loads on the casting.
Posted August 13, 2008 - 11:43 AM
Get BC3 to weld it - he's really good and won't leave pinholes.
Posted August 13, 2008 - 01:57 PM
Oh yea, I have a puller, a cheap hardware store model that does the job, and my buddy has a case splitter if I need to use it.
Wish me luck,
Posted August 13, 2008 - 03:42 PM
Posted August 13, 2008 - 08:11 PM
Have a box of sandwich bags handy. As you take secions apart, put all the parts in the bag. Then do the next section. If you can, line them up on the bench in the order they came off.
I like taking digital pictures while disassembling something new to me. Take lots of pics with good resolution and you can review them later. A factory shop manual is also invaluable.
Posted August 13, 2008 - 08:35 PM