280 lbs. 750sx-f build

been doin some thinkin,
i have an old cylinder that needs new sleeves, so i was gonna re-sleeve it and have it bored to around 800cc. i was also gonna lower the port timing, and mill my stock head. so what if i milled the bottom of the cylinder which would lower the stock ports, and not open them up so i wouldnt have to worry about losing the amount of air being compressed. This would also raise compression. So the question is, would milling it enough to make any noticeable difference make the squish too small? has anybody done this before?
 

Waternut

Customizing addict
Location
Macon, GA
I asked a similar question when I was porting my motor. I didn't have any intention of milling the bottom of the cylinder but instead lowering the port window a tad instead of raising it.

The basic conclusion that was presented to me was that the port window on a 750 was below the top of the piston anyway so it wouldn't do any good to lower it more. Plus, the piston comes right to the edge of the top of the cylinder.

Secondary notes to keep in mind...
I believe if you ran flat top pistons you could get away with a smaller squish.
Resleeving a kawi cylinder is not cheap like a yamaha cylinder!
Might want to ask in the aftermarket forum on all this though as I'm no expert.
 
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the 750's have flattops stock. or maybe just a tiny dome than you cant see?? Anyway, it looks like im still gonna buy your porting templates, do you still have em?
 
little update,
got my -2 rn pole:Banane09: and bracket setup for 2 inch breather. so i need to know, if i plug up the air intakes on top ( both sides are opened up cuz i got it from a racer) and cut open the holes in the back of the hood, is that enough air? and sorry for the crappy phone pics
 

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N3vrSat1sfied

Military Member
Location
Fort Worth, TX
hey i got an extra hood that i am working on turning the stock air intakes into handholds and cutting new air holes in the back above the dash next to the hood latch like a RN SJ hood. I am also cutting the round pertrustion (that comes off above the rails) and making it more flat which will close those air intakes as well. But the liner i am using has the front liner cut where the hood meets the pole. Hard to explain. so i personally think will be enough air. If i had a camara around here i would snap some pics. I got one side cut.

Also i havnt put the timing adv on yet. I Dont want to pull my exhuast off again but when i do, do you still just use that o ring? early in your thread someone mentioned a thicker gasket
 
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cool, how are you gonna seal the holds over the air intakes on top of the hood? i was gonna cut out the original hood liner but i don't know if thats possible, has anyone done it before?

and ya just the stock o-ring
 

N3vrSat1sfied

Military Member
Location
Fort Worth, TX
i am just gonna glass in homemade holds so there wont be air intake on top of the hood and it will be sealed by the dome of the hold. I will try to get pics tomorrow or friday. i got one side cut right now.
 

Mark Gomez

is where the surf is
Location
Fullerton, CA
little update,
got my -2 rn pole:Banane09: and bracket setup for 2 inch breather. so i need to know, if i plug up the air intakes on top ( both sides are opened up cuz i got it from a racer) and cut open the holes in the back of the hood, is that enough air? and sorry for the crappy phone pics

Yeah Luc thats how you make it work.
Good job keep going.
 
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