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Old 07-18-2014, 08:00 PM
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Davezilla Davezilla is offline
Motorized Bicycle Elite Member
Join Date: Mar 2014
Location: San Antonio Texas
Posts: 2,710
Default Re: My first motorbicycle - Rico engine

port cleanup looks good, where you hit the wall near the transfer will be ok as long as it's not a deep gouge that runs the same direction as the rings (horizontally), but even then it would just need a little polishing and would most likely end up a non issue. the important stuff is to clean up the extra plating flash that ends up in the ports because it can start flaking off from those areas but once cleaned up and chamfered it completely prevents that potential problem.
There is a casting seam inside the transfer ports at the roofs that should be cleaned up if you can get in there with a dremel, pencil grinder, or even jeweler's files, it is worthwhile to clean that area and the engine will perform slightly better.
You can also cut about 5mm off the rear (intake side) of your piston skirt to allow more air fuel charge in and increase intake duration to a more respectable level, and if you look up "piston indexing" or "piston cutting" you'll find an easy way to unlock even more power.
Adding an extra base gasket will make more power on top but less on the bottom, or using a thinner base gasket will make more on bottom at the cost of some at the top, and lapping the head or having it milled down by about 1mm will raise the compression ratio for better power thruout the rpm range.
there are a lot of other tricks to get more out of these little engines that you'll learn as you go but those little tricks will make a noticeable difference. Just be sure to ask someone before doing the more advanced mods to the engine before you start cutting on stuff if this is your first time working with a small 2 stroke... You can make these things run like mad with the right mods, but you can mess it up big time if you cut too far or in the wrong places, but people in here will help if you ask before you cut.
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