Serious porting questions?

[Larry's Shee]

The vito's piston is cut down @the exhaust to give a little more exhaust timing, although they make that piston with the rings lower also. I didn't check either time I tore down but was told on here that the transfer ports are .5 mm lower than piston @ BDC. I am going to check before I put it back together to get a better idea what goes on with this motor. Personally I wouldn't spend the money for a spacer and decking the cyl. I want to get a +3 stroker, no spacer, and have Ken O do the head for it. That way I can lower the floor of transfers to gain more time/area values.

Been so long since I read Gorden Jennings I can't spout off exactly the different effects of port timings have, but he does mention moddifying pistons in exactly that method for "testing" port timings, to see if a particular engine (or rider) likes it. if it wasn't for only having about ten hours on a new piston, I might play with it.

Just remember that a little is a lot, 1/32" is a lot in degrees of crank rotation especially at mid stroke when ports are opening.

 

[Prime]

@Larry's Shee: That sounds right...I'm pretty sure the transfers are .5mm lower than the crown of the piston at bdc.. and the exhaust port floor is 1mm below the crown of the piston at bdc.

All of that is fixed with a stroker crank and some porting. B)

 

[super noober]

hooray for stroker cranks and porting!!! lol I:I

 

[Blaner]

i dont like the idea of cutting pistons! thats like grinding off the roof of your sedan to make it a convertible...never going to be the same!

 

['00 WO-YA!]

Haha, thanks Blaner for the info you sent, I tried to PM you but things were acting wierd.

Typically stroker systems use a new custom piston that relocated the wristpin higher so that the piston is in the correct position @ tdc, ultimately the sweep of the cylinder is longer b/c the piston will drop lower, I guess that's why it works well to uncover the ports. Having said that, I don't see much about stroker correct pistons so what are you guys using?

 

[super noober]

Haha, thanks Blaner for the info you sent, I tried to PM you but things were acting wierd.

Typically stroker systems use a new custom piston that relocated the wristpin higher so that the piston is in the correct position @ tdc, ultimately the sweep of the cylinder is longer b/c the piston will drop lower, I guess that's why it works well to uncover the ports. Having said that, I don't see much about stroker correct pistons so what are you guys using?

most everyone uses wiseco pro lites, just the standard ones , no relocated pin or anything like that. i did nothing to my piston to accomodate my stroker crank. i use the spacer plate and had it ported to match perfectly

 

[Blaner]

nothing wrong with spacer plates...they only leak if you use rubbish gaskets and dont torque properly, ive never had a problem EXCEPT when i used a green paper one.

 

['00 WO-YA!]

So we still need the spacer plate for a stroker then? Where do I look for that?

 

[super noober]

So we still need the spacer plate for a stroker then? Where do I look for that?

you can have the head cut so u dont the plate, its up to you and your builder. if it has a spacer plate it would be between the cylinder and the cases

 

[Blaner]

a spacer you can have laser cut...i emailed you the CAD design of the spacer, all you do is find someone with a laser cutter and give them the CAD (.dwg) file i sent you! specify the thickness you need though. easy as pie

 

[Awk08]

So we still need the spacer plate for a stroker then? Where do I look for that?

i believe i heard that cometic will make you any thickness spacer you'd need

 

[super noober]

i believe i heard that cometic will make you any thickness spacer you'd need

yup, they sure do I:I but damn if blaner has the file already i think im gonna go that route

 

['00 WO-YA!]

Noober, milling the head will only effect the quench area, not sure why you think I wouldn't need the spacer for a stroked engine? Am I missing something?

 

[super noober]

Noober, milling the head will only effect the quench area, not sure why you think I wouldn't need the spacer for a stroked engine? Am I missing something?

some builders build the motors to not use a spacer plate, wildcard being one of them, im not sure of the exact process but i belive it has to do with redesigning the head

 

[Awk08]

some builders build the motors to not use a spacer plate, wildcard being one of them, im not sure of the exact process but i belive it has to do with redesigning the head

ken also builds at least the +3's to run "no spacer plate"
not sure about his +4 longrod motors < but may soon ???

 

[Larry's Shee]

It would be like a stroker dome on a banshee. You would have 1.5mm straight, like a mini cylinder, then it would start the actual dome/combustion area.

 

[super noober]

It would be like a stroker dome on a banshee. You would have 1.5mm straight, like a mini cylinder, then it would start the actual dome/combustion area.

ok thats pretty much what i was thinking, flotek builds his bikes to run a custom spacer from cometic for the insane custom builds and then just the regular spacer on normal builds. other than a sneaky look i dont belive there is a advantage to either style

 

['00 WO-YA!]

"Sneaky" doesn't matter to me, I just want function besides, after some black paint & a lil riding dirt, you'll have to look super close to notice it, lol!

 

[brandoz28]

ken also builds at least the +3's to run "no spacer plate"
not sure about his +4 longrod motors < but may soon ???

he uses a spacer on those motors. if a guy had the budget, that would be the route that I would want to go. the stroker long rod motors are insane

 

['00 WO-YA!]

Cool, longer rod= better rod angle, always things to consider. I'm also still considering triple ports. I've read that I should stay about 3mm per side away from the main port. Can anyone give me an idea of how far back in the port I should come when trying to drill toward the cylinder? I wanna be very careful not to blow through the outside.