4 mill porting?

[gofast5]

Im going to build a 4 mill im planning on using 115 rods stroker pistons and stroker domes. Do the cylinders need to be ported?

[firebanshee]

Im going to build a 4 mill im planning on using 115 rods stroker pistons and stroker domes. Do the cylinders need to be ported?

Yes,if they are already ported you need to see if they can be reported for the crank.If you have cylinders that are ported aggressively you cant report them.

[toytech]

Im going to build a 4 mill im planning on using 115 rods stroker pistons and stroker domes. Do the cylinders need to be ported?

 

no, but to get the full potential of the 4 mill crank yes

[shakar]

if your allready ported for stock stroke crank and go to 4mm crank . will the spacer plate '' i know it 's better to cut domes'' but will the plate put ur jugs up to where they need to be ? thanks

Edited June 4, 2010 by shakar

[odaen]

if your allready ported for stock stroke crank and go to 4mm crank . will the spacer plate '' i know it 's better to cut domes'' but will the plate put ur jugs up to where they need to be ? thanks

Mechanically, yes. But your port timings are gonna be insanely high since you effectively raised them 2mm.

 

For instane, a typical dune port has durations of about 194 ex and 128 tran. Assuming a zero deck height and adding a spacer, those port timings go to 202 ex and 143 trans which would be a very peaky narrow powerband. If you ditch the spacer plate and cut domes, it drops it back to about 194.4 ex and 133.6 trans.

[shakar]

so cut domes would stiil be better, even if ur running a portjob meant for stock stroke on a 4 mm crank?not runing the plate u would think would put u 2mm to low to match ports up up with the xtra strke ?? or am i thinking about it worng?? thanks for the great info

[odaen]

so cut domes would stiil be better, even if ur running a portjob meant for stock stroke on a 4 mm crank?not runing the plate u would think would put u 2mm to low to match ports up up with the xtra strke ?? or am i thinking about it worng?? thanks for the great info

You're thinking of it backwards. You are lifting the cylinder 2mm. So, imagine the piston being at a specific spot in the stroke, then slide the cylinder 2mm up with the piston stationary. It raises all of the ports 2mm from where they were originally.

[gofast5]

I shouldve stated this from the begining sorry guys. I currently have cylinders that are ported but only the intakes and transfers were done, he didnt change the exhaust at all I don't think. This is how the bike was when I got it. Can I safely run these?

[odaen]

The transfers are going to be more impacted than the exhaust. I don't recall the stock transfer port height, but I think stock dropping in a 4mm crank with cut domes puts the transfers at about 130 duration.

[Darthwall]

from what I understand the spacer is fine if you just want to drop in a 4mm crank you will see a lil difference but not much more talk than show! if you add those you have stock stroke drag ported or what ever cylinders and raise them 2mm there will be no bottom end and a quick surge up top meaning no power until 5k or 6k or? it will run but you will not get the full potential

[gofast5]

no, but to get the full potential of the 4 mill crank yes

 

 

Well I have cylinders but they have mainly a clean up port no exhaust port work. They opened the intakes and worked the transfers some. Will I be able to safely run these? As long as Im not going to lose power im just going to put these on. My bike now has no porting whatso ever and needs a new crank so im wanting to put the 4 mill in now instead of later down the road.

[toytech]

Well I have cylinders but they have mainly a clean up port no exhaust port work. They opened the intakes and worked the transfers some. Will I be able to safely run these? As long as Im not going to lose power im just going to put these on. My bike now has no porting whatso ever and needs a new crank so im wanting to put the 4 mill in now instead of later down the road.

[/quote

 

 

I put the 4 mil crank in with the spacer plate and it worked fine ,I just wanted more power so I'm getting my cyls ported by F.A.S.T racing, just putting the crank in will give you more power than you have now just not a lot, then when you port it it should add a ton of power

[camatv]

i am pretty sure jeff will tell you to ditch the spacer plate and get cut domes OR the thick head gasket used with the stocish heads.

 

i cannot imagine a bike with 140's+ transfers. i'm not sure how it would run. the 202 would be pretty insane but useable ( kinda) but the trans being that high.. YIKES> plus the piston is droping so much lower than the floor of the port..

[gofast5]

no, but to get the full potential of the 4 mill crank yes

 

 

Well I have cylinders but they have mainly a clean up port no exhaust port work. They opened the intakes and worked the transfers some. Will I be able to safely run these? As long as Im not going to lose power im just going to put these on. My bike now has no porting whatso ever and needs a new crank so im wanting to put the 4 mill in now instead of later down the road.

[firebanshee]

Well I have cylinders but they have mainly a clean up port no exhaust port work. They opened the intakes and worked the transfers some. Will I be able to safely run these? As long as Im not going to lose power im just going to put these on. My bike now has no porting whatso ever and needs a new crank so im wanting to put the 4 mill in now instead of later down the road.

If your cylinders just have a clean up port and have just been opened up so they flow better then you should be ok,it is just when the port timings have been changed alot you cant use them.