038 super top end rebuild

[KarlD]

I've rebuilt a couple of 038 Supers. My method for putting the cylinder on is first to squirt a little 2-cycle oil on the big end crank bearing and then by moving the crank around, get access to the points where I can squirt a little oil into the crankshaft bearings. Turn the crank around a few times to distribute the oil. then put the piston, wrist pin, and that pesky circlip in. Turn the unit over and put a couple of drops of oil on the wrist pin bearing. I don't oil the rings or the piston. The cylinder also goes on dry. The mating surfaces are squeaky clean. I use Yamabond 4 on both mating surfaces and gasket if used. I want the sealant and mating surfaces completely free of oil. After the cylinder bolts have been torqued, I turn the crank around a couple of times by hand, dry, just to make sure everything is OK and there is no binding. Then I leave it a couple of days for the Yamabond to set up fully. At that point I put a few drops of oil on the front cylinder surface through the spark plug hole and on the back surface through the exhaust port. Then turn it around a few times and everything is oiled and ready to go for startup. Also, if you forgot to oil the big end bearing, you can turn the crank to where the bottom of the piston is above the intake port and dribble oil down the connecting rod.

Thank you for the pointers, they all make sense and definitely better than my approach. I’ve already got the feeling that I will enjoy rebuilding the saw as a magnum in the near/mid future...if I do I will use your method
If the saw keeps running strong I might just hold on for a 038M project to come along and have a pair

 

[president]

behind inner bar plate, in slot over tensioner screw.?

T1

 

[rocketnorton]

not as big a diff between super n mag as ya might think.
bing vs zama makes more diff imo.
got good mag. been 3 supers here. one had zama, not for long.

 

[KarlD]

not as big a diff between super n mag as ya might think.
bing vs zama makes more diff imo.
got good mag. been 3 supers here. one had zama, not for long.

I can’t even remember which carb my 038 has...I’ll have a look back through the thread. Thanks for the info

 

[KarlD]

So my saw has the bing carb...is that the better one? I used it today for about an hour, lovely beast

 

[rocketnorton]

imo, bing works best on s or m.

 

[Mad Professor]

not as big a diff between super n mag as ya might think.
bing vs zama makes more diff imo.
got good mag. been 3 supers here. one had zama, not for long.

You sure about it having a Zama carb? Never seen one on an 038.

The early ones and supers had Tillotson, but the super carbs are a litter bit bigger venturi. The magnums came with the Bing, that is same size bore as the super Tillotson.

I've switched between the Tillotson and Bing carbs on magnums and they both seem to run about the same. Parts are much cheaper for the Tillotson.

 

[rocketnorton]

i had one s w/zama, another w/tilly - it ran ok. did not like zama. 3rd had bing.
tilly one was actually on am top end, brand unknown. ran pretty good. friend has that one now.... so i'll hear of any probs...
i hoard bing, so zama took a hike.

edit. i dont throw much out, so prolly stihl have the zama.
i could maybe dig it up if yer interested in pics, #s, etc.

 

[Mad Professor]

I've rebuilt a couple of 038 Supers. My method for putting the cylinder on is first to squirt a little 2-cycle oil on the big end crank bearing and then by moving the crank around, get access to the points where I can squirt a little oil into the crankshaft bearings. Turn the crank around a few times to distribute the oil. then put the piston, wrist pin, and that pesky circlip in. Turn the unit over and put a couple of drops of oil on the wrist pin bearing. I don't oil the rings or the piston. The cylinder also goes on dry. The mating surfaces are squeaky clean. I use Yamabond 4 on both mating surfaces and gasket if used. I want the sealant and mating surfaces completely free of oil. After the cylinder bolts have been torqued, I turn the crank around a couple of times by hand, dry, just to make sure everything is OK and there is no binding. Then I leave it a couple of days for the Yamabond to set up fully. At that point I put a few drops of oil on the front cylinder surface through the spark plug hole and on the back surface through the exhaust port. Then turn it around a few times and everything is oiled and ready to go for startup. Also, if you forgot to oil the big end bearing, you can turn the crank to where the bottom of the piston is above the intake port and dribble oil down the connecting rod.

I don't like the idea of putting things together dry.

You can lube and clean the bottom end by putting some mix in it, turning the crank a few turns, then dumping the mix out. This will get to the crank bearings and lower rod bearing, as well as flushing out any nasty stuff that may have snuck into the bottom end.

I add few drops oil to the lower rod bearing. The upper rod bearing as well, with a light coating on the upper rod bearing bore, piston pin, and inside piston pin bore. You can wipe any excess off after putting in the circlips.

The piston and cylinder I coat lightly with oil using my finger.

For gasket surfaces, wipe any excess/dripped oil before installing cylinder. Once the piston is inside, you can wipe those surfaces again with isopropanol using a q-tip. I don't think that is needed unless you are not using a base gasket. If using a base gasket I put a very thin film/coating of sealer on both sides of the gasket and leave the surfaces bare.

Q-tips work well if you want to apply sealer to the mating surfaces for a gasket delete once the piston has been started.

The sealing surfaces should be smooth and free of old gasket material and any gouges.

 

[TheTone]

I don't like the idea of putting things together dry. . . .

By the method I use, the big end bearing, crank bearings and piston pin bearing are oiled before assembly. I put sealant on both mating surfaces and assemble without oiling the piston or cylinder. This is because I don't want oil seeping down the cylinder while I'm trying to get the rings into the cylinder. If the rings are oiled I'm sure to get it on my fingers and probably on the mating surfaces (for me, even with a ring compressor it may take several tries). After assembly the dry piston and cylinder are turned by hand through only one or two revolutions to check for binding, the sealant is left to dry, and then the cylinder walls (and thus piston and rings) are amply oiled and turned by hand so that the entire system is well oiled for startup. I get a good bit of smoke that first start before it burns off. I don't see how two dry revolutions by hand can do any harm.