This is great and answers another question! It states that the 545 had adjustable oiling,,, which means it most likely used the original 540 style oil pump. So the 545 is a hybrid between the 540 and the 8800. 540 oiling (which also means a 540 crankcase being as the oil pumps are completely different and not interchangeable.), and an 8800 metal tank. A remaining question then is how did it grow by 1 cc? The 540 is an 88cc engine while the 545 is described as being an 89cc engine.
There are significant differences between the 540 and the 8800 cylinders and porting. They use different mufflers with different mounting flanges and the intake transfer port design seems a bit more open in the 540. It was about this time that most saws were going to lower compression ratios due to the changes in motor fuels going to unleaded, so I'd guess that the 8800 was also a lower compression ratio.
If the 545 is a hybrid that used the 540 crankcase and the 8800 tank/handle case, did they also use the 8800 cylinder? While that is possible, and a drop in compression ratio may be due to a larger combustion chamber, then it seems odd that an 8800 is still an 88cc saw. Regarding the cylinder, a front picture of one would answer the question about being based on the 540 or 8800 because the two mufflers use a different screw pattern to attach the muffler to the cylinder.
Lastly, for anyone who cares, you can interchange a 540 cylinder/piston to an 8800 or 8800 to 540 providing you have the matching mufflers, screws and gaskets.
Here's a bit of info I put together a few years ago,,,
This information is intended to aid people who are trying to find parts for Homelite 540 and 8800 chainsaws. Since these saws are no longer produced and parts are hard to find, I'm hoping to help keep them running and to avoid the frustration of getting parts that will not work.
My experience on this subject has been primarily with the chainsaws, but since the multi-purpose saws are closely related and I have spent countless hours researching parts, including comparing all available parts listings between the families, I am including subject descriptions that cover several related areas.
Right now I have what appears to be an original, nearly mint condition 540, a second used 540 that I'm rebuilding, and a very nice 8800 that may have had some work done to it before I got it. For reference, I suggest using the parts listings for the 540, 8800, DM54 and MP88 saws that can either be accessed online through the Homelite website, or purchased in hardcopy on eBay.
Homelite built several motors using essentially the same design, and most parts can be interchanged as long as the mechanic understands the interrelationship between motors, clutches, ignitions, cases, oil pumps, intake and exhaust ports and their associated components.
The 540 and 8800 chainsaws, and the DM54 and MP88 multi-purpose saws share the same basic engine design with various changes made to the handles, cases, intake and exhaust ports, and mufflers. At this time, I believe the crank and rods are identical, and the crank cases are nearly the same with only minor design changes. Starters, ignitions, carburetors, and mounting hardware are essentially the same and should be interchangeable. Case, handle, and clutches are essentially interchangeable between the chainsaws but there are design variations between the families based on airbox design, air filter type, drive type, and fuel/oil storage.
The chainsaws use a separate oil and fuel chamber in the handle assembly, while the multi-purpose saws use the entire space for fuel. The chainsaws have an integral oil pump driven off of the chain clutch, while the multi-purpose saws do not. An oil passage is cast and drilled in the 540 crankcase, while the 8800 uses an oil line direct from the oil tank to the pump. The chainsaws use a direct drive chain clutch with an integrated oil pump drive, while the multi-purpose saws use a belt drive clutch without any type of an oil pump or drive. Clutch components should be interchangeable between the chainsaws, and interchangeable between the multi-purpose saws, but are totally different between the two families.
Cylinder design changes between the 540 and 8800 involve port layout, muffler mounting, and carburetor adaptor mounting. Also there may be design changes between the factory Homelite parts, and aftermarket replacement parts. On the original 540, the intake port on the cylinder is an open semi-oval shape, and the adaptor between the cylinder and carburetor has tabs to fill in the opening, converting it from an oval to a round port. This design may have originally been intended to serve for a reed valve intake, but was not utilized in the examples I have seen.
On the 8800, the intake port on the cylinder is cast as a round opening, and the tabs are no longer used on the carburetor adaptor. This provides for a full round passage from the carburetor to the crankcase and would require the correct matching adaptor for the appropriate intake design.
Using an 8800 cylinder on the 540 would require either grinding the opening on the cylinder out to an oval shape to use the original 540 adaptor, or cutting the tabs on the 540 adaptor off so it can be bolted directly to the 8800 cylinder. Also, to use an 8800 cylinder on the 540, the 540 muffler either has to be modified (fairly difficult) or an 8800 design muffler has to be used.
On the 540, the exhaust port uses three internal screws in a triangular pattern to mount the muffler, (which includes an internal baffle) while on the 8800 two long bolts in a side to side pattern are used. Please note that the two bolts on the 8800 pass through the body of the muffler and that the whole assembly is essentially a one piece design. The 540 muffler has three main parts, (inner shell, outer shell, and internal baffle/mount) and requires removing the outer shell to access the internal mounting screws. While the exhaust port is the same shape and in the same position on both designs, you have to worry about getting a good seal around the port and getting things screwed together to make it all work.
At this time, I'm planning on using an MP88 muffler on the 8800 replacement cylinder and except for minor design differences, there should not be any problem with using this muffler. Currently, (July, 08) there are a few MP88 mufflers available on eBay from user "gm17621" and they are listed as "Brand New Oldstock Muffler for a Homelite Concrete Saw". Since a spark screen is required for chainsaws, I'm hoping that the MP88 either has one, (shown in the parts lists) or can use the screen from the 540 muffler…(the exhaust outlet plate can be swapped and except for the screws, they appear to be interchangeable).
Another apparent design change between the 540 and 8800's involves the pistons and cylinder transfer ports. My 8800 was bought used and may have an aftermarket replacement cylinder, so at this time I'm not sure about the original 8800 design. Regardless if this is an aftermarket item, it appears to be identical to the replacement set that is still available as part number UP07137, and I will do my best to compare it to the original 540 design.
Pistons; the original 540 piston was cast with a full skirt and used two thin rings. The replacement design uses skirts on the main thrust sides, but not below the wristpin. While this most likely makes no difference in performance or durability, it is something to note. I could theorize that it would reduce friction, but again this is only guessing. The replacement also uses two thick rings, versus the twin thin ring design or the 540. Guessing again, this may slightly reduce top speed RPM, but may enhance durability. Possibly, when combined, the reduced friction of the redesigned piston may balance out with the thicker rings to achieve the same top RPM.
Transfer ports; the original 540 cylinder has transfer ports that are cleanly cast and taper from four individual sections down to the two openings in the cylinder. The replacement design has two individual sections that taper to two smaller openings in the cylinder. Possible differences in performance,,, can't say for sure. Guessing again, I would think that the 540 design would enhance transfer by offering a greater opening area. Then again, the smaller area of the replacement design may offer greater velocity through the ports and actually perform better. Don't know. Pistons should be interchangeable between either cylinder, with their ring and crown positions being compatible with either design.
Summary; yes, it can be done! Just be prepared to mix and match a bit. Good luck!
J. Ralph
