Homelite 150 Automatic Project

With the completion of the MS241 behind me, I've moved on to another project. Taking two Homelite 150's and and making one good one. The red saw had a good cylinder but sloppy crank bearings as well as mag rot on the bottom of the case. The blue saw has a tight bottom end but a scored cylinder. The case is in excellent condition outside of some paint missing. I prefer the blue so it's getting the good cylinder as well as a new, N.O.S. piston and rings I've hoarded. I'm also eliminating the points with a chip. I'm slowly getting things cleaned and sorting out the best parts to use. Here are some pics of the situation.

 

MAF143

That red chassis is camp fire bound...

 

My dad had a 150 Auto back in the late 70's to early 80's or there abouts. It was the first chainsaw I ran and I cut a lot of firewood with it. It was red and the plastic was black if I remember correctly. Running that thing for an hour my hands and forearms would be tingling from the vibration for days. He replaced that saw with a 024 and the difference was incredible. I still have fond memories of it.

 

Yep, Red and black. The older saws were metallic blue and white. These two make 10 of these I've had. Lol. CAD....

The vibration is the worst of any saw I've ran so they are more of a novelty to me vs useful tool, especially considering the modern saws I have. I still find them neat as there's nothing else quite like them style wise.

 

I have one of those that I should let somebody adopt. Cosmetically it doesn’t look too bad.

 

Dok440 needs one...

 

Cool build! Can't wait to see it all finished up. And I agree on the vibration in those 150's. It's terrible!

 

I've made some progress. There is a lot going on here so bear with me. Probably useless to most but here it is anyway. There are differences between the older and newer homelite 150's besides colors. These are the oil tank, pump and cylinder pics from the later red unit.

Below is the old blue saw.

 

No for some explanations.

The red saw saw draws oil in from the tank and out to the bar pad via that nipple on the right. Both saws use crankcase pulse to operate a diaphragm.

 

On both saws the pulse goes through the hole in the center where the rod passes through the crankcase. Circled in blue.


That pulse enters the pump through the hole with yellow dot and up into a chamber on one side of the diaphragm.

That pressure / vacuum pulse moves a rubber diaphragm with a piston on it that fits in that center hole.
I used the better of the two during assembly.

 

Ok, one might ask why does this matter. I'm getting to that. You cannot just swap a cylinder from a late model 150 to an early model without modification because the difference in bar oiling is in the tank body, pump itself and the cylinder. I'll attempt to illustrate that now.
On the older saw the pump is driven the same way as explained above but the oil flow takes a different route. For some reason the old cylinder had this vent hole that leads to the back side of the diaphragm. The newer saw doesn't.


That little vent hole lines up with the hole, circled in red, in the pump housing / crankcase bottom.

I modified the later cylinder with the same hole.

 

Now oil flow. As previously stated, the newer saw draws in one tube and pumps out another directly to the bar pad through a nipple. The old saw is more complex. It draws oil in and passes it through channels in the crankcase bottom / oil pump housing, out against the mating surfaces of the top / bottom crankcase via a slot, then takes 180° turn into a passage in the side of the oil tank body to the bar pad.


Up the tube, left through that passage and out...
Out of that slot on top right making its 180° turn and back out the hole on the far left with arrow pointing up.
That hole seals against the tank body, with a gasket, feeding the passage to the bar pad. Below is that passage. I can aee why they changed this design to the much simpler later version because there is much less machining involved. There...everything you never needed or wanted to know about homelite 150 bar oil systems.

 

Not quite everything… so all blues are the same, and all reds are the same. So as long as you keep the color the same, you can mix and match all you want? or are there differences with each color?

 

Nice detective work! How long were you scratching your head over that? Totally unexpected. I imagine the redesign saved them some money.

 

I've had 10 of these counting these two. I believe all blue are the same but I've had red saws both ways.

 

Thanks bud. I tend to nerd out on mechanical stuff. I knew there were two oil systems from all the others I had but I didn't realize the cylinder is different as well with that one added vent hole. I have never swapped a top end from one version to another before. There is definitely more machine work in the older version.

 

Looking good best of luck on this build

 

Thanks bud. I hope to have it finished today but old saws often have other ideas. Lol

 

Pic heavy progress.

First, the blue saws original points in the left, the red saws points installed on the blue saw. Different size pin in the cylinders where the points rotate on.