4 mill stroker questions

[dajogejr]

not trying to jack the thread but im curious. why is the bottom spacer plate better than the one that goes between the jugs and head?

 

Good question...I'll give you my opinion.

There is more pressure on the head and it's sealing surfaces than the base of the cylinder.

But probably more importantly, you're be raising the ports in the cylinder...and due to a longer stroke, that's what you want.

 

I don't port cylinders, I'm not going to guess what a builder will do to your ports as far as raise then, open them on the bottom, etc...

 

This is a very general statement, but you'll want the ports raised to accommodate more stroke (2mm on top, 2 on bottom) to get the charge in faster and the exhaust out faster.

 

 

[Darthwall]

pORTING HELP IS LIKE THE EVIL QUESTION ON HERE. i SEARCHED FOR LIKE 4 NIGHTS STRAIGHT TRYING TO FIND WHAT i NEEDED TO DO. tHE BEST THING i CAME UP WITH WAS THIS LINK.

Stolen from ODAEN, thanks for a great post.

 

http://www.planetsand.com/programs/portmapper.zip

 

tHIS ONE SHOWS HOW PORT HEIGHTS CHANGE THE DURATION & BLOW DOWN. BLOW DOWN SHOULD BE 30 - 35. 30 IS FOR A LIGHT GUY & BIKE ADD MORE FOR HEAVIER RIDER. I put mine at 32. iTS A DOWNLOAD BUT ITS GREAT.

 

& tHIS IS STOLEN FROM MISTERWW425, tHANKS A MUCH MAN FOR THE FIGGURES .

 

PORT TIMING VALUES FOR RPM RANGE.

THE FIRST DURATION IN THE XXX-XXX FORMAT IS THE MIN FOR THAT RPM.

EXAMPLE: TO GET TO 9000 RPM YOU HAVE TO HAVE AT LEAST 184 EXHAUST

AND 123 INTAKE

 

EXHAUST TIMING

7500 RPM 176-178

8000 RPM 180-182

8500 RPM 183-185

9000 RPM 184-186

9500 RPM 186-188

10000 RPM 190-192

10500 RPM 193-196

11000 RPM 196-198

 

TRANSFER TIMING

7500 RPM 120-123

8000 RPM 121-125

8500 RPM 122-126

9000 RPM 123-127

9500 RPM 124-128

10000 RPM 127-131

10500 RPM 129-133

11000 RPM 130-134

 

Hope this helps & I wish this was put on just as a general tip for porting. Also being easy find would be great. Like I said it took hours & hours to find this. It doesnt teach how to dirrect flow, flatten the top of the exhaust, knife edging the intake splitter, shaping the transfers, & such but it gives you a place to start your measurements.

 

sweet this is exactly what I was looking for

[tedd1]

...you'll want the ports raised to accommodate more stroke (2mm on top, 2 on bottom) to get the charge in faster and the exhaust out faster.

 

Exactly!

 

Run the spacer under the cylinders. That is the only way to compromise if you are planning on running the stock cylinders without porting.

It works fine. I ran one in my bike for a season. I installed the 4 mil, long rod crank after spinning a rod bearing. Put a plate under the cylinders, ran stroker pistons under a stock head.

 

Rick

[yammyboy3]

im not sure if the pistons i have are stroker pistons or not there 795m6600 im not going to run a spacer under the cylinders im going to do a port job and use the headgasket plate i had one guy on here nice enough to give me measurements to what i need to do !! THANKS MAN so im waiting to here back from jeff at fast cuz when he got my cylinders he said they were BADDDD shape i had groves in the right intake side down bottom and they were torqued down to much and ran im really starting to love the guy i got the bike from seems he didnt take care into putting this motor back together and im just experimenting with this top end in the first place i found a set of stock bore unported cylinders that i might get for 130 shipped and im going to get them bored . honed to one size over with a dune/play port with a noss head with 20cc stroker domes all machinging done bye jeff at fast im going to let it all sit on the side for when this top end goes

[RagunCajun]

was also thinkin about just running straight c12 with this head gasket do you think itll all hold up ?? or just run the 93

I would go for pump gas man. Race fuel is expensive and for the gains vs cost, pump gas will be fine. I'm doing a 4mm stroker right now on pump gas. It should rip hard.

 

Have you ever thought of buying some cheap used juggs close to stock bore for about $150-$200 and get them ported. That way youll be good to go for many more top end rebuilds. Then have it ported for the 4mm set up and not have to worry about spacers plates or anything special.

Edited March 29, 2009 by RagunCajun

[yammyboy3]

I would go for pump gas man. Race fuel is expensive and for the gains vs cost, pump gas will be fine. I'm doing a 4mm stroker right now on pump gas. It should rip hard.

 

Have you ever thought of buying some cheap used juggs close to stock bore for about $150-$200 and get them ported. That way youll be good to go for many more top end rebuilds. Then have it ported for the 4mm set up and not have to worry about spacers plates or anything special.

 

 

yea i think i might just do pump gas right now im just trying to get a set of cylinders back on the bike i still dont know if jeff at fast is able to fix the screwups in my cylinders and i need to get this refund from advance auto to grab these other stock bore cylinders from a nyuk

 

[yammyboy3]

well i got another set of stock bore stock port oem cylinders that im going to be sending off i think im going to give hjr a call this time and talk to him about work being done to these cylinders i cant wait to get cylinders back from fast so i can see his quality and ill get these others done bye hjr and see how i like that quality then ill know who my new machinist is so for all you people out there that have a 4 mill how do yous like the power and whats it like compaired to stock rods