Convert An EZ To An SEZ?

[edju1958]

Been doing a little thinking on this.I'm wondering if it's possible to convert an EZ (38cc) to an SEZ (41cc)?The displacement is in the bigger piston & bigger cylinder.If they would just bolt up -  the piston to the crankshaft & the cylinder to the crankcase.I don't really see why they wouldn't,I'm sure that Homelite didn't go to the extreme of making the 2 saws that much different (cost effectiveness).

                                                                 Ed

[rowdy235]

If anybody can do it, its you Ed with your large collection of EZs and SEZs lol.

I agree with your thinking, pry just a different piston and cylinder. Maybe take a look at the IPL to see if the crankcase parts are the same between the models?

[undee70ss]

It would be out of balance unless the crank was changed also.

[onlyhomelites]

Looking at the IPL's, the crankcase is basically the same between the models, but remember that Homelite had a run of their narrow skirt cylinders before switching to the wide skirt. A-65202 superseded to A-65202-A, which accounts for the extra machining for the wide skirt cylinders. So you'll need to match everything thing up...a narrow skirt cylinder will have too much clearance in a wide skirt crankcase. I don't think you can visually tell the difference with one assembled, except by the casting number on the cylinder.

[edju1958]

Mar 8, 2020 8:40:28 GMT -5 undee70ss said:

It would be out of balance unless the crank was changed also.

I was assuming that Homelite used the same crank to keep with the cost effectiveness.This was just a late night idea that popped in my head with no research.

                                             Ed

[onlyhomelites]

The EZ Automatic and Super EZ did use the same crankshaft, so that part would match up okay. It was just a bore increase between the two models.

[edju1958]

Mar 8, 2020 9:36:12 GMT -5 onlyhomelites said:

The EZ Automatic and Super EZ did use the same crankshaft, so that part would match up okay. It was just a bore increase between the two models.

That's pretty much what I thought.So why was I told that I'd have to change the crankshafts?I understand how Homelite minds worked when it came to saving money the best way they could.There are some parts that were used on the EZ's as well as the Super 1050's (not engine-wise).

                              Ed

[onlyhomelites]

Some models had stroke and bore changes which would require changing a crankshaft (like the difference between A Super XL and an XL-500)...the EZ did use a different crank, but the EZ Automatic crankshaft carried over to the Super EZ.

[Hoggwood]

On a side note...

I have converted earlier 2.3 ci XL-1 with the smaller piston (single L ring) and decompression valve to the larger 2.5 ci XL-1 AO and Super Mini setups. Cranks and rods were the same. You can also convert the manual oiler only (single pickup)  drivecase on the Xl-1 to accept the auto pump equipped on the bigger XL-1 and Super Mini saws. The drivecase pump blanks need to be drilled out and the bypass filled to reroute the oil through the auto pump. The screw bosses need to tapped and the pump mounts accordingly.  I don't know the ez series variations, but the Terry cylinders/pilots match across the XL-1/XL-1AO/Super Mini saws.  Makes for upsizing.

I am just wrapping up another project that incorporated the crank/rod from a '75 red XL-1 onto the top end of a 73' Super Mini.  The drivecase is from another '75 XL-1 (manual oiler only) but has been converted back to accept the original pump from the '73 Super.  It is essentially what the Super Mini would have been from the factory.  

I picked up up the '73 Super Mini this week, but it had a '73 blue XL-1 drivecase with the non-functioning auto pump mounted to it. There were a few issues below the surface, so I broke down 3 saws to get it all in order.

[hightop]

I have been thinking about the same thing, I'm looking to replace my more modern Stihl and Husky saws with just Homelites, an XL-12 for my "big" saw, EZ for midsize, and a Super 2 for a top handle, to that end I recently bought a non running EZ, I haven't disassembled and inspected it yet, but doing some reading and research I've noticed a discrepancy.

The manual thoughtfully provided here lists the stroke of the EZ and EZ Auto as 1.3" stroke, and the Super EZ as 1.3125" stroke, this is also as listed on the Acres website. If the Super EZ had the 1.3125" stroke however, the math shows it as 2.516 cu.in., or 41.23 cc, with the 1.3" crank, 2.492 cu. in., or 40.85 cc, the Acre site says it is 40.9 cc, leading me to believe all the cranks are the same stroke, 1.3".

As running a Super cylinder and piston with a shorter than designed stroke would cause compression and port timing issues, can someone on here who's more knowledgeable than me confirm which stroke the Super EZ is? Thanks in advance.

[sweepleader]

Mike Acres says his data came from a Homelite source long lost in history. I have to believe if it could be located, it would actually be the same Homelite source you found.

I would say the only real way to determine the answer to your stroke issue would be to find the original engine prints or to measure the cranks on several engines. As the difference after the math is less than .5cc, I would tend to believe that the issue comes up from rounding errors. .0125" is a pretty small number, it would be very easy for a tech writer to round 1.3125 to 1.3. I would guess that the real stroke is 1.3125 since that is a normal fraction, 5/16. They were likely going for 2 1/2 cubic inches as a general goal decided on by marketing. 1 5/16" got them close. Back in the days that these saws were designed, fractional inches would have likely been the measurements of choice. 1.3" would have been an odd ball and cubic centimeters would in my opinion have been a later conversion.

[hightop]

Thanks for the input, I guess I'll measure what I've got, and if it's not 1.3125", I'll buy a Super crank off Ebay and see if it is, they're not that expensive.

[hightop]

Ok, to confirm for anyone in the future, tore down my '69 EZ and measured, the stroke is 1.3125", so all I need is a piston and cylinder to go from the original 2.1 cu. in to the Super EZ 2.5 cu. in.

[hightop]

Been working on this saw a little from time to time, I bought a Super EZ cylinder and piston, when I tried to mock it up to check squish with no base gasket I found that the EZ crankcase is the "narrow case", no surprise I guess, so I bought a Super EZ crankcase, I just tried to mock it up again and have now discovered that the piston pin is a larger diameter than the EZ, and won't fit the EZ rod, so I'll buy a Super EZ rod, and report back if that's the final item necessary to do this conversion, for anyone who might want to do this in the future.

At least parts are readily available for these saws.

[hightop]

Got the rod today (actually bought a drivecase, crankcase, rod and crank assay, cheaper than just a rod), you should be able to see the difference in the small end bearing size between the two.

[hightop]

Finally found time to put this together and get it running, I think it's a '70, not a '69, sn 03340150, ended up using an SEZ crankcase, rod, and piston make it work.

Now I need to find a blue clutch cover and the peice the handlebar bolts to which is now orange, the previous owner attempted to fix a crack in the clutch cover with epoxy, didn't work to well.

I bought this saw as a non runner on EBAY, I think the only thing that was wrong with it is that the condenser wire was pinched and shorted to ground when the condenser was screwed down.