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Porting cyls w/ racelogic template and 4mil short rod


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i did this one just recently. its nothing crazy but makes for a good duner. 192exh around 90% wide. staggered transfers alittle under 130 and widened a bit. changed the trans angles alittle bit. slightly reworked head. compression ratio barely over stock. modified stock reed cage and custom petals. 41pwk with sunoco gas. overall theres no large sacrifices in any one part of the power range. runs decent on the topend and pulls fairly well below the pipe. for what it is it'll go up the hills pretty well. ive built some faster but they arent suited nearly as well for the average guy looking for a good duner machine

 

 

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I'm stoked to get the cylinders back! Aside from removing material to increase and direct flow... I took some advice and am curious to see where the timings end up. There's about 1 1/2 weeks til the 'shee needs to be trail ready, so I hope it's close enough!

Finally decided to go through and figure out where I started from, mostly to have a baseline because I liked how the previous setup responded.

192 / 125 / 33.5. With 4mil 110 rod, stock port, spacer plate, and Vito's Superstock Pistons.

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youll have to fill me in how you ended up at 194/130. do you have a spacer plate in there ? im thinking your blowdown will be insufficient especially because you have no aux ports and your main port probly isnt real wide. a port timing number only tells you how long the window is uncovered or partially uncovered in crankshaft degrees. it doesnt have anything to do with the width. if you notice on the previous page why i really widened the exh above the transfers.

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I'm not really impressed with those numbers either. Not that I know much about them, but I know what I was shooting for. Thinking about trying a thinner base gasket, or even taking a little off the bottom of the cylinder. That's about all I can think of to drop those #s a little, and to raise the exhaust enough to get a better blowdown #.

Like I said, the transfer heights are untouched, and the exhaust was moved up and that's how I ended up at 194. But at least I didn't over-do it right off the bat, and have room to work with things.

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OK, I need some schooling here. What´s wrong with those numbers? (194/130)

My opinion is, if that´s a gas motor, I wouldn´t go over 32bd(nor 194exdur) at first. You can always take them off and raise the exhaust later IF needed.

I did that mistake and went up to roof with 35bd with pump gas, and believe me the powerband sucks for a heavyer rider.

 

Right now I have 110% overported door stoppers and I hate them.

 

But anyway, you´re doing good work!!

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Actually the numbers I got weren't far off of what I had with the short rod 4mil and Vito's super stock pistons with the stock cylinders. Those were 192/125/33.5.

The reasons for doing any changes with the new setup is only because I had certain #s to get. But as of right now everything is put together, I plan to start it tomarrow. The domes I got, put the compression at 120psi and 0.060 squish with a 20cc chamber. I'd like to see a narrower squish, and possibly higher comp, but will be safe to ride... leaving on a trip thursday

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