Another 4 mill question

[bigborebanshee]

I got a spare engine with a 4 mill crank,stock cylinders that were template ported.Neither the transfers nor exhaust ports have been raised,just cleaned up and widend a bit.

The cool head has cut domes,so i would not be running a spacer plate.My question is this...could you run a Vitos Superstock piston to get the exhaust port timing closer to stock(vitos claims the exhaust port cutout on piston is 1.75 mm)

 

Has anyone had any experience with these pistons or can advise on the setup?

 

Reason being,i have a banshee that i am putting together for the GF....I know without a full port,it will be limiting it,but Im not ready to drop that kind of coin on a quad that will see minimum action.

 

Anyone with input on port timing?

[sleeper06]

If you use cut pistons you go further away from stock,add duration

[bigborebanshee]

If you use cut pistons you go further away from stock,add duration

 

But what about on a 4 mill that does not run a spacer plate and uses cut domes?The current cylinders have stock port timing?

Can i get similar results with a cut piston or should I just invest 60 bucks into a spacer plate?

Edited November 6, 2009 by bigborebanshee

[banshee_terror_]

from what ive herd and under stood you need the 4mill port or your motor is not going 2 runn right. so i would get that done first

[romelo1680]

if its vito 4mm short rod you need the plate. when i spoke to him he told me that he was coming out with so piston that you wouldn't have to use the plate . i have one of his 4 mm cranks and i dont want to ues it because of the spacer plate

 

 

[crustydemon]

I dont understand the spacer plate under the cylinders concept. With a 4 mill your are already approx 2mm to high on the bottom of your exhaust and transfers then you intentionally raise your jugs another 2mm?Thats just dumb. If you insist on using a plate and stock head, use the one that goes between the head and jugs and drop your ports 2mm, That way you dont ruin a set of jugs that could later be used with a aftermarket head and replaceable domes.imo thats the way to do it.

[RILS]

I dont understand the spacer plate under the cylinders concept. With a 4 mill your are already approx 2mm to high on the bottom of your exhaust and transfers then you intentionally raise your jugs another 2mm?Thats just dumb. If you insist on using a plate and stock head, use the one that goes between the head and jugs and drop your ports 2mm, That way you dont ruin a set of jugs that could later be used with a aftermarket head and replaceable domes.imo thats the way to do it.

 

That is assbackwards. When u run a 4mill stroker crank the pin is offcenter from stock position 2mm making the piston travel 2mm farther down and 2mm farther up. You can run a spacer if you want and do nothing or you can run a spacer and drop the transfer floors to the new piston postion or you can run cut domes and do whatever you want to the porting. The rod doesent matter if you run a 110 rod run 513 series pistons or the short rod bigbores I cant remeber the # if your running the 115 run the 795 series or the blaster pistons make sure whoever cuts the domes knows what pistons you are going to run. I have a spacer plate if somebody needs it for $25. And after typing all that I just reread his post and he is correct that you will be rasing all your timing up with the spacer but if the jugs are stock they will do ok and yes if you drop the floors to make up for the plate they will always be to low for a 4mill crank without the plate best option is to get some domes cut and do the porting right.

Edited November 8, 2009 by RILS

[AKheathen]

....haha, that's great

[crustydemon]

You had me worried there for a second, I thought I really f***ed mine up.

[AKheathen]

i have a spacer plate that i'll trade for stroker domes of the right size you can use a plate to run it fine. it just desn't make as much power. domes without porting will keep the timings to low to keep up with a stock engine. this includes the transfer timings

[bigborebanshee]

i have a spacer plate that i'll trade for stroker domes of the right size you can use a plate to run it fine. it just desn't make as much power. domes without porting will keep the timings to low to keep up with a stock engine. this includes the transfer timings

 

Thats what i was tryn to figure out.Im not going to invest much since it will be ridden sparingly.A plate is much cheaper..as long as the timing is corrected

[J-Madd]

Throw a space plate on there and see how it runs. Like you said, it's not gonna be ridden much anyway.