2-stroke engine mods for more speed
04-01-2004, 09:49 AM
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2-stroke engine mods for more speed
I want to get the most power out of an OS .10 for a club racing event. My two thoughts are to bore the carb and possibly mill the head for more compression. I need help!
04-01-2004, 02:15 PM
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RE: 2-stroke engine mods for more speed
I did the following mods to a Thunder tiger .25 GP and gained 2000 rpm, went from 14500 to 16500 with a 9x4 prop on 15% fuel.
Raised the exhaust port 10 degrees (duration).
Added an oil ring groove on the piston, some engines already come with this feature.
Set the head clearance at .015", most sport engines come with way to much for longevity reasons.
Clearance on the crank to connecting rod set at .002-.0025", this frees up some RPM.
Chamfer the boost and intake ports on the sleeve.
You could also bore out the muffler outlet slightly.
Check the engine case to muffler joint, make sure they match. I personally would not bore out the carb unless you feel the opening is really on the small side. I think this can lead to fuel draw problems and a very sensitive needle. I would also run 20-25% nitro. Experiment with different heat range glow plugs, this effectively changes the ignition point, like advancing and retarding it. Try a mc coy mc-9 and mc-8 and see which gives the most rpm.
Hope this helps
Raised the exhaust port 10 degrees (duration).
Added an oil ring groove on the piston, some engines already come with this feature.
Set the head clearance at .015", most sport engines come with way to much for longevity reasons.
Clearance on the crank to connecting rod set at .002-.0025", this frees up some RPM.
Chamfer the boost and intake ports on the sleeve.
You could also bore out the muffler outlet slightly.
Check the engine case to muffler joint, make sure they match. I personally would not bore out the carb unless you feel the opening is really on the small side. I think this can lead to fuel draw problems and a very sensitive needle. I would also run 20-25% nitro. Experiment with different heat range glow plugs, this effectively changes the ignition point, like advancing and retarding it. Try a mc coy mc-9 and mc-8 and see which gives the most rpm.
Hope this helps
04-01-2004, 05:41 PM
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RE: 2-stroke engine mods for more speed
Usually removing the head shim gets it pretty close. I have seen shims from .005 to .015 thick on various engines. I have also made some from aluminum shim stock.
