25 cc Homelite Help
02-22-2004, 12:11 PM
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25 cc Homelite Help
Hey guys, I recently aquired a 25 cc homelite from my neighbor who was throwing it away because "it didnt work"....I noticed the problem within 5 secinds...broken fuel line...So I snatched it, took it all apart and cleaned it up. I have a 57" deep-V that im going to transplant the motor into...(it had a smaller McCulloch in it before). Now, I need a little help modding the motor. I already turned the head for the water jacket, lightened the flywheel, and made a new exhaust manifold for a pipe. Now, I work at a machine shop, so I have access to all the machines. I need some help with bumping the compression. Im going to turn the bottom of the head on the lathe, and I know I have to re-adjust the timing on the ports...BUT, how can I check the compression? My friend has a compression tester for his car, but I dont think the threads are the same. I could weld something up from an old sparkplug, if that would work. Also, is removing the squish band necessary if I bump the compression? Next part of the puzzle is a carb...I know everyone says Walbro 167A, but WHERE do I get it?!? I can only find ones on ebay that arent 167A. As for the duraion and timing numbers on the ports...should I put them back to the stock numbers, or bump them up...if so...to what? As for ignition timing, what are some numbers to shoot for, and how do you get that damn key out of the crank? With regards to the water cooling...Should I get an extra pump for the jacket for when im idleing? or will I be ok with the intake on the rudder alone? If I do need a pump, what one? The only one I have found is a Prather one on tower hobbies. The final piece (for now 
) is the prop..right now I have a Prather 270 (2.74 Dia, Pitch: 4.2" ) Is this ok, or is there a better one for this application? Thanks in advance for all your help!
) is the prop..right now I have a Prather 270 (2.74 Dia, Pitch: 4.2" ) Is this ok, or is there a better one for this application? Thanks in advance for all your help!
02-22-2004, 10:06 PM
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RE: 25 cc Homelite Help
Hi Chris, auto tester will work for compression testing. Plug wrench size is 3/4" but threads are the same. As for the carb, you can get your local weed eater shop to order you one. Or there are a few r/c boat sites that have them. http://rc-speedworld.com/index.html and http://www.rocketcityracing.com/tek9.asp
Check out http://www.shark-racing.com/Ingles/Sobrenosing.HTM for specs on homelite timing and mods. Click on technical tab, they have a lot of info on homies.. Water pump is a must for engines w/ a clutch. small outboard fuel pumps work well for this, also the above sites can fix you up with whatever you need.
As far as the prop goes... it really depends on power output and hull weight. The 270 is a good place to start, but you will have to try others to find the right one for your combination.
BTW try to keep the compression psi below 140, homies wont be reliable above that and may blow cyl off of case. Hope this helps. Nitropower
p.s. save up and get a zenoah g231 or 260 its worth it!!
Check out http://www.shark-racing.com/Ingles/Sobrenosing.HTM for specs on homelite timing and mods. Click on technical tab, they have a lot of info on homies.. Water pump is a must for engines w/ a clutch. small outboard fuel pumps work well for this, also the above sites can fix you up with whatever you need.
As far as the prop goes... it really depends on power output and hull weight. The 270 is a good place to start, but you will have to try others to find the right one for your combination.
BTW try to keep the compression psi below 140, homies wont be reliable above that and may blow cyl off of case. Hope this helps. Nitropower
p.s. save up and get a zenoah g231 or 260 its worth it!!
