Over the weekend I re-powered a 1987 MTD model 604 edger replacing the original 3 horsepower engine with a brand new Lifan LF160F-AQ engine. The new engine is 4 HP and 118cc displacement, and comes with a 3-year warranty. The original engine was a tired 3 HP Briggs and Stratton with a broken recoil starter. The inside of the gas tank was not looking too good either.
Here is the before picture. I had cut a hole in it and used a 24 mm impact socket on the crankshaft to start it with an electric drill the last few times. This was not a long term solution.
Here it is after I removed the Briggs and Stratton model 80202-1830 engine and cleaned off the deck. I also replaced all four wheels and put on a new blade and drive belt before changing engines. I also changed the two 5/8" ball bearing on the blade assembly. It spins like a brand new edger.
Using a 10" length of 1x6 pine as a riser, I drilled mounting holes in the original spots since the new engine need about 3/4" of height. For mounting I used 4 stainless steel hex bolts 5/16x18 and 2-1/2" long, with stainless steel nuts and lock washers. The original bolts were 1-1/2" long. The board is just the right length to still see the MTD nameplate.:
Next I mounted the brand new 4 HP Lifan LF160F-AQ engine. The mounting holes lines up perfectly. It was a perfect fit though a tight fit. I would say this is the biggest engine that would physically fit the edger.
Note that the Lifan engine fits perfectly and does not interfere with the wheel height adjustment bracket of the MTD edger, not at all. I saw on YouTube a guy had used a 79cc 3 HP Predator engine from Harbor Freight and could not get it to fit without completely cutting off the height adjustment bracket rendering it inoperable.
I bought a new 2-1/2" pulley to replace the MTD 2-3/8" pulley that is now unobtainable. Using an abrasive sanding drum on a Dremel tool I took down some metal on the height adjustment bar so it does not hit the crankshaft keyway. I took off maybe 3/16". The pulley has two Alen screws one pressing down on the key and the other 90 degrees away tightens on to the crankshaft. I used blue Loctite on both. The engine takes a 3/16x24 crankshaft bolt I have not bought one yet.
The trickiest part was hooking up the remote throttle cable so the engine is WFO throttle when the lever is pressed all the the way. It took some fiddling at both ends of the cable and adjusting a tension screw on the throttle so the lever on the handlebars is easy to move yet holds its position. I also added an induction type hour meter. I filled it with 17 ounces of Mobil 1 Advanced 10W-30 and some 94 octane gas. The tank takes 2/3 gallon and is quite a bit bigger than the one on the old engine which I think was one quart.
The new engine started on the first pull I let it idle at various speeds for 15 minutes no load then put the MTD to work again both as an edger and as a trim mower. When done I let it idle at no load a few minutes to cool down then shut it off. The new engine now has 1.0 hours on it.
The 4 HP Lifan engine is a lot more powerful than the 3 HP Briggs, more than the extra 1 HP would suggest. Before buying this engine I did some reading that it is considered quite powerful for a "4 horsepower" engine. Moving the throttle lever to idle it is so quiet you can hardly hear it. Wide open it is still quite a bit quieter to the Briggs and has a smoother sound to it. It made mincemeat of areas that the old engine could not cut and that would actually stall the Briggs engine. It did not bog down in the RPM one bit. It was astonishing the difference in power. The slightly larger pulley turns about 5% faster than the original MTD pulley.
Here is the before picture. I had cut a hole in it and used a 24 mm impact socket on the crankshaft to start it with an electric drill the last few times. This was not a long term solution.
Here it is after I removed the Briggs and Stratton model 80202-1830 engine and cleaned off the deck. I also replaced all four wheels and put on a new blade and drive belt before changing engines. I also changed the two 5/8" ball bearing on the blade assembly. It spins like a brand new edger.
Using a 10" length of 1x6 pine as a riser, I drilled mounting holes in the original spots since the new engine need about 3/4" of height. For mounting I used 4 stainless steel hex bolts 5/16x18 and 2-1/2" long, with stainless steel nuts and lock washers. The original bolts were 1-1/2" long. The board is just the right length to still see the MTD nameplate.:
Next I mounted the brand new 4 HP Lifan LF160F-AQ engine. The mounting holes lines up perfectly. It was a perfect fit though a tight fit. I would say this is the biggest engine that would physically fit the edger.
Note that the Lifan engine fits perfectly and does not interfere with the wheel height adjustment bracket of the MTD edger, not at all. I saw on YouTube a guy had used a 79cc 3 HP Predator engine from Harbor Freight and could not get it to fit without completely cutting off the height adjustment bracket rendering it inoperable.
I bought a new 2-1/2" pulley to replace the MTD 2-3/8" pulley that is now unobtainable. Using an abrasive sanding drum on a Dremel tool I took down some metal on the height adjustment bar so it does not hit the crankshaft keyway. I took off maybe 3/16". The pulley has two Alen screws one pressing down on the key and the other 90 degrees away tightens on to the crankshaft. I used blue Loctite on both. The engine takes a 3/16x24 crankshaft bolt I have not bought one yet.
The trickiest part was hooking up the remote throttle cable so the engine is WFO throttle when the lever is pressed all the the way. It took some fiddling at both ends of the cable and adjusting a tension screw on the throttle so the lever on the handlebars is easy to move yet holds its position. I also added an induction type hour meter. I filled it with 17 ounces of Mobil 1 Advanced 10W-30 and some 94 octane gas. The tank takes 2/3 gallon and is quite a bit bigger than the one on the old engine which I think was one quart.
The new engine started on the first pull I let it idle at various speeds for 15 minutes no load then put the MTD to work again both as an edger and as a trim mower. When done I let it idle at no load a few minutes to cool down then shut it off. The new engine now has 1.0 hours on it.
The 4 HP Lifan engine is a lot more powerful than the 3 HP Briggs, more than the extra 1 HP would suggest. Before buying this engine I did some reading that it is considered quite powerful for a "4 horsepower" engine. Moving the throttle lever to idle it is so quiet you can hardly hear it. Wide open it is still quite a bit quieter to the Briggs and has a smoother sound to it. It made mincemeat of areas that the old engine could not cut and that would actually stall the Briggs engine. It did not bog down in the RPM one bit. It was astonishing the difference in power. The slightly larger pulley turns about 5% faster than the original MTD pulley.
