Honda Spree and Elite 50 Forums

This has become an ongoing project that I've been documenting for myself and you (if you're interested in my bs) on my preparation for the installation of the 50mm bore kit on dio motor. I have added a pic of the widened and raised exhaust portmap. I left the transfers where they come stock. Raised the exhaust 5-6 degrees or roughly 1mm. This increased my blowdown as shown on the spreadsheet following. A link to the bigbnrg blog is included in the following that will explain port timing better than I can. Ill be running a malossi crank, yasuni c16, and 26mm polini pwk replica. Im hoping for solid power at 12k, a street suitable racing setup. This build will heavily depend on the c16. Enjoy!
Exhaust: ~180 degrees
Transfers and boost: ~125 degrees Ported exhaust: 186 degrees

hi dirty. Thanks for posting the map. If you make any changes will you post it ? Thanks

Gathered info for timing calculations;
41.4 stroke
6mm squish
80mm conrod
Distance from the top of the ports to the cylinder top.

Ill try to get a mhr replica portmap today while im there as well.

Anyone here that has a corsa they could post? We could start a new thread with common dio port maps

looks like this is going to be a nice build...
swimmingfree

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There is much debate online about what port duration is good for 12k, and the corresponding blowdown. I havent found a solid pipe for making power at this rpm yet anyway, although one may be in the works. Tuning this cylinder would be silly if there isnt a pipe that would work with it.

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I understand there are many factors to setting the rpm where you want power to be made. As well, I do not have the financial luxury of sending out kits for professional port work. Im happy to take measurements as accurately as possible and try to learn something from it. I have always had success with my port jobs, as they've made me happy. Not professional, backyard all the way. Ive had great luck in having friends worldwide on forums that will analyze the data with me.
I know tuning high rpm is not easy. Ive been there. It is endless and exhausting. Jet and roller/spring changes lead to striped bolts and nuts from constant removal and replacement.

Ive had many p ipey setups. Ill get there again.

I have not been in dio land long. I dont see a pipe that is reasonably priced that I trust. For my mina and piaggio builds it was easier; go find dynographs and pic your pipe.

Btw, 13 is higher than I want to spin. 11-12k.

My scorpion pulls fine at 11250 all day everyday on my corsa .The ports are stock on the cylinder but i mirror finished the top of the piston and the head and the export.Pics of my bike and scorpion pipe in G9s calander thread .

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I got to look a little closer at my cylinder today. Im impressed with how well the opening of the transfer ports are all fairly even. I've seen kits that are more than a millimeter off. All transfers should open at the same time. I havent gotten my timing figured out yet, but a good chamfer will even these ports out.

I think I want to cut out the bottom of the lower boost port in the cylinder skirt. I havent seen it closed off like that before, but Ill wait to do a mock up with the new crank installed to see how far down the piston travels.

looks more like just scuff marks from where he moved the ring into place .