4 mil/115 rod set up

[thrill-billy85]

Helping out a friend with his banshee. He ordered a 4 mil long rod crank (against my advice) its not been ported, and will not be any time soon.

 

Question is- whats needed in the way of piston choices, and possibly spacer plates (il advised I KNOW). Custom milled head?

[blue97shee]

you can get a spacer plate to go under the cylinders to correct the port timing and get the extra room for the longer stroke.  Not the best way to do it, but it will work.  I believe the Wiseco 795 series pistons are what you want to get.  He woulda been better off porting with the stock crank, woulda been cheaper too.

[thrill-billy85]

Well he had to buy a crank anyhow. I thought the biggest spacer you could run was 2 mm? Hes gonna have to make up for an addl 9mm of total stroke?

[Colby]

call up a builder, talk to him about what your wanting, get some custom cut domes and wiseco 795's..  forget the spacer plate

[Coupelx]

Well he had to buy a crank anyhow. I thought the biggest spacer you could run was 2 mm? Hes gonna have to make up for an addl 9mm of total stroke?

The pin is offset 2 mm from stock. The piston goes up 2 more mm and down 2 more mm, thus 4 more mm of stroke.

[sheerider11]

 

The pin is offset 2 mm from stock. The piston goes up 2 more mm and down 2 more mm, thus 4 more mm of stroke.

And the 795 piston takes up the extra 5 from the rod

[Nieskes]

 

Well he had to buy a crank anyhow. I thought the biggest spacer you could run was 2 mm? Hes gonna have to make up for an addl 9mm of total stroke?

HUH??????

[blue97shee]

the long rod doesnt change the stroke. only the 4mm stroker crank changes the stroke.  

[blue97shee]

the 795 pistons have the wristpin 5mm cloer to the top of the piston when compared to a stock piston, thus making up for the longer connecting rod.  The longer rod gives you more dwell time at top and bottom dead center, giving a little extra time for the transfer ports to fill the cylinder.

[Coupelx]

The longer rod lessens the angle of the rod mid stroke reducing the side load on the piston. The piston also accelerates/decelerates at a slower rate. While it is true that dwell is increased it has no particular effect on cylinder filling.

[4everwantedbanshee]

I got the same set up and runs like a monster....i use the spacer plate with 795 series pistons...works awesome...i have milled head and dune ported cylinders so it runs hard.

[RadarRacing]

Just run the right pistons and get the correct domes in a coolhead of he doesnt have one. That is all.

[trickedcarbine]

People always say their shit runs hard. Then they get a real motor with a proper set up and learn what "runs hard" really means.