Nooks and cranies

[DanMan1]

I'm thinking about filling the 4 casted depressions in the crankcase with some clear silicon, so there is less places for chips and dust to accumulate. Does anyone see a reason why I shouldn't do it?

 

[Lobo]

I'm thinking about filling the 4 casted depressions in the crankcase with some clear silicon, so there is less places for chips and dust to accumulate. Does anyone see a reason why I shouldn't do it?

Cooling !

 

[sedanman]

Bingo!

 

[DanMan1]

I thought of that, but figured not much cooling happened at that point of the engine, especially once chips got in there.

 

[Lawn Masters]

You dont want to take that chance and ruin a perfectly good saw now do you?

 

[rahtreelimbs]

Just keep it clean and don't let the dirt build up!!!

 

[DanMan1]

You guys have huge amounts more experience with saws than me, And I respect everyones opinions, but I have a hard time envisioning these casing connectors contributing squat to the cooling of the saw. Some of you sound SO sure it will cause trouble, Is this because you have tried something similar and saw a failure, or are you just speculating also?

 

[sedanman]

Heat from the saw is carried away by surface contact with the air. Pugging these holes permanently reduces the surface area of the crankcase. Is this amount of rediction in this location enough to cause a problem, I doubt it but plugging the holes vs. leaving them has a very small gain to risk ratio.

 

[WRW]

I'm thinking about filling the 4 casted depressions in the crankcase with some clear silicon, so there is less places for chips and dust to accumulate. Does anyone see a reason why I shouldn't do it?

The cylinder fins need a blast of air every so often to keep them clean and while there, you could just give those depressions a blast to clean out the dust. If there is any oil residue, that should be removed or the silicon probably won't stick. I think it's more trouble than it will be worth. But that's just me.

Is the saw out of warranty? Go for it.

 

[Crofter]

The reason for the depressions is to save the material the casting is made from. Where they are located under the clutch cover guarantees they will be filled immediately. If they always remained unplugged they coould contribute some cooling. What difference would it make plugging with silicone? I mean would it be a gain.

 

[glens]

To save material and weight, but probably equally as important to ease production.  The bosses could have been supported by solid material instead of ribs, but that increases the amount of time and complexity required to let the castings cool without shrinking in/with unwanted ways/consequences.

I'd say if you're worried at all about the voids becoming filled with oily wood dust, it would be perfectly fine to top them off with something you like better.  They are not cooling fins and there's not a great amount of heat being dissipated there, if any to speak of at all.

But I wouldn't give the situation a second thought either way.

Glen

 

[SIRCHOPALOT]

for cooling? are you kidding? these are not for cooling. the crankcase on a twostroke probably never gets above 120 deg. the cool fuel charge keeps it cool from the inside. the depressions are there to reduce weight. instead of casting it solid they put in what is called webbing. that is what the holes are. it provides strength with less weight, and also saves the company money in material. save a little on each piece and soon you have enough for another piece. it pays for itself. And yes you can fill them without any harm, I would suggest an epoxy such as JB weld. just rough up the surface and make sure it is good and clean.

 

[SIRCHOPALOT]

glens also makes a good point about the cooling of the part when it comes out of the die. cools much faster than a solid piece, and thus speeds production.

 

[njforestfire]

Good point SIRCHOPALOT....definately not for cooling...that is what the fins on the cylinder are for.

 

[glens]

I don't have any direct experience with die-casting metal, but do with plastic, and I'm quite confident they share the same problems.  Namely, when there is a relatively large mass of material, the piece must be kept in the closed die longer and with continued pressure on the injected material, or the larger mass will cool too quickly with attendant shrinking/cracking which may be merely unsightly at best.  A bearing boss with internal cracks/voids will not be as strong as one which has less material overall but which is solid and has well-formed structure throughout.

Glen