Crankcase Screws

[Cypher04]

So I am having an issue getting these to come out and I am wondering if I am missing something...these screws seem exceedingly soft to me, I'm not kidding when I say that I have stripped 2 of these by hand. On top of that the extractors that I have a just ripping these things apart, it is like I am using a drill bit instead. Any Ideas on how to get these out?

[taber hodaka]

Are you using a impact driver you have to hit with a hammer??
Clarence

[Cypher04]

No, I am thinking about getting an impact driver tomorrow, all I have used is a screwdriver, I am concerned that an air tool will do more damage...And I have considered using a hammer...but only out of frustration...

[thrownchain]

Look at your screwdriver tip. Is it square and straight ? not rounded over? Also it also should be big enuff to fill the slot in the screw head. If it's a good tight fit and you can get good leverage on it, most of the screws should pop loose.

[Dale]

I just came in from my shop having just split the cases on a 94 Wombat. I take a heat gun (electric) and carefully heat each screw (about 20 seconds each) and then use the hammer impact driver. They pop loose very easily with this method. As mentioned above, the hammer driver is a good choice and make sure that the bit is in perfect condition.
Dale

[Dale]

I would also add that it is helpful to build a wooden block, with holes drilled into it for each of the protruding shafts to fit into. Then you can lay the motor on its side. This makes dis-assembly and re-assembly a breeze. There have been previous posts with pictures showing how to build this block. I can look for it further if you can not find it...
Dale

[hodakamax]

The Gang always has good advice, the only thing I would add is use a #3 bit (a must!). A hammer driver is a must on these decades old screws. A battery powered impact tool is the weapon of choice today. Get the engine on it's side and really put the weight on the driver. I've not tried Dale's heating of the screws but it all sounds like it would help. Everybody always fights the first case screw removal But it's relatively easy with the right tools. Good Luck!

Maxie

[Dale]

Well, it is just easier to post a couple of pictures rather than search for pictures of the wooden jig...

Wooden jig with case half and internals. Setting in a turkey roasting pan to catch any falling bearings and rollers.

Wooden jig with handles.

Wooden jig to mount assembled cases to that allows complete motor assembly. Held in vise.

As for any screws that already have their heads stripped out... you can use a drill bit that is the same size as the 6mm screw. Drill down (very carefully) from the center of the head. When you have reached the threaded part of the screw, the head will be severed and begin to spin on your drill bit. Again, extreme care is needed to keep from making any contact with the case itself.
Good luck,
Dale

Edited update: Like Max, I do like my battery powered impact drill/driver, however, for the case screws, I have had better luck with the old fashioned, handheld, impact driver. I use a plastic mallet for my hammer.

[taber hodaka]

I think Dale could be very correct as the bolt with the tapered head is only tight at the taper. I usually had trouble with the smaller ones at the backing plate, I hit a small bit in with a small hammer and then use a small ratchet. I will hope the heat gun helps me there also.
Clarence

[Bullfrog]

. . . and I feel like I must re-iterate . . . you MUST use a #3 Phillips screwdriver. Most folks have a well worn #2 - which is the first step toward disaster.

Looking at the dynamics involved, a hammer "driven" old fashioned impact driver is probably the best option. Though those new-fangled air or electric impact tools work well too. (they just don't provide the compressive impact which is inherent when an old fashioned impact driver is used)

Ed

[Cypher04]

Well the good news is that I got the case open, the bad new is that I think the case it toast. It looks like it chewed up part of this bearing
http://www.strictlyhodaka.com/Bearing-p/bb6204_99rt.htm
and that punched through the case In a place that was not visible...

[Dale]

While that is certainly bad news, don't give on the cases just yet. There are people with the skills to fix broken cases (not me by the way). Can you post pictures?

[Cypher04]

I have not been able the find the piece that broke off.

[thrownchain]

That gap in only one half of the case halves? Or both? If it didn't fall out when you split the cases, most likely wasn't put back in by previous owner. From the angle of the break that piece was pushed out, so would have been in the cavity behind the motor mount boss.

[Cypher04]

The crack is only in this half. It's strange, this motor has never been apart yet I can't find that piece. This is the position I took it apart in, the remnants of the bearing were still on the crank shaft, and the screws were full of mud as well. Someone would have put a lot of effort into re-covering this thing in mud if they had disassembled it. I will look again in the morning, it could have stuck onto the other half and fallen as I moved it over the the bath.

[thrownchain]

The bearing you have as a listing didn't put that hole in the case, most likely a piece of a piston got between the case and the crank wheels and broke thru. It's been apart before you, and it's been run since the re assembly, as long as that front chamber was sealed there would be no pressure loss an it would run, not saying it would run good, but run it will.

[Cypher04]

Ok I had been thinking that this all happened at once. so the question is, can the case be fixed as ddvorak suggests.

[Bullfrog]

I agree with thrownchain, it is quite likely that a piece of piston broke off and jammed and broke the case web -- in addition, bits of that failure could then easily damage the bearing.

I too think your case is "save-able" -- but if you decide to throw it away . . . send it to me and I'll make good use . . . , er, um, I'll properly dispose of it for you.

Ed

[Dale]

It could be some time before one of the capable Hodaka machinists sees your post (and they may not spot it). So, here is a link to a list of Hodaka specialists from the Strictly Hodaka web site. I would suggest finding one of them that does case repairs and have them evaluate it. I do believe that it can be fixed, but at what expense, I have no idea.

http://www.strictlyhodaka.com/SearchRes ... p?Cat=1870

[Cypher04]

Ok, Thanks, I will put together an email and contact a few of those people. I am quickly discovering that the engine and carb are about out of my wheelhouse so I may just send it all of for a rebuild.

[thrownchain]

The welding and machining is the hard part, rest is easy.

[rlkarren]

That case is definitely repairable, IMHO. We have a guy here locally that repairs Boat Propellers and he repaired my Super Rat cases for less than $100. His repair was good enough that you cannot tell it was damaged. He's very precise. The front motor mount was broken and a large piece around the flywheel was broken off. I should have taken pictures, but I forgot.

As far as crankcase screws, I think drilling the head off is probably the best way to go. The screw should come right out after relieving the clamping pressure from the screw head. Although I have in the past used a small punch diagonally on the screw head to break them loose after stripping the head with an impact driver.

$0.02

Roger

[hodakamax]

This probably would work and is a little crude (I'm sure I'll get a few comments on this one) but you could fill the entire cavity outside the missing piece with some epoxy based filler. The area is not hot but has pumping pressures. By filling the entire cavity your repair would not blow out. I don't see any reason it wouldn't work. These materials are easy to work with files and such.

My old short tracker had a clutch come apart and one of the screws exited through the bottom of the crankcase leaving a 1/2 x 1 inch hole. I patched it with such material and it lasted for years.

Something to think about and it would be cheap. As for the carb, it's no more complicated than your toilet. You can do it and the Gang will help if you get lost.

Max

[Zyx]

Filling with epoxy:

I won't say it wouldn't work, but sounds more likely to raise problems rather than fix them. First, there are two cavities that mate to make one larger cavity. The damage is to only one half of the case, but involves both halves. You would either have to fill both sides or fill one so that it could be machined to make a mating, sealing surface that would seal out pressure. I have no idea if epoxy would suit such a repair by holding on to the surrounding metal and also machine closely enough to make a sealed surface when the halves are mated. I don't think epoxy expands at the same rate as aluminum and it may not hold a seal, at which point you would be pretty much where you are now but with a smaller leak. If it didn't work, taking it to a welder for proper repair would then be pretty much out of the question largely because you couldn't get all the epoxy out, or at least out of the way enough to weld up without a bunch of grinding that the welder isn't going to want to deal with.

Also, although it appears to have been running as is, I wouldn't put it back into service as is. There would be no way to make proper pressure with that large an expansion area under the crank and it would or could just fill up with oil and gas, which wouldn't lead to proper running.

I would just have the case fixed correctly rather than risk making them unrepairable.

[hodakamax]

After studying this a bit more I would have no reservations on fixing this with epoxy and only in the broken side. The seal is only where the piece is missing. The unbroken case is going to bridge the gap and the epoxy is going to be the gasket surface backed up by filling the entire hole and filing it flat. Of course welding would be best but used crankcase halves are not rare and could be purchased probably for the cost of repair. All I am saying is that you could get years of life out of the engine with a do it yourself repair for about $10-20 and a flat and rotary file.

My free opinion.

Maxie

PS-you'll probably miss this because Technical Stickies keeps coming out on top and and we all will think there are no new posts.