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7 mil stock cyl setup


Ayesully810

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I got a pair of pretty nice stock cylinders that I plan on using for my drag build this winter.  I'm for sure using these cylinders no questions asked, but I'm trying to decide if I want to do a 4mil or 7 mil.  I already have the person picked out for porting.

What special things need to be done on a stock cyl setup to make the 7 mil work. I haven't researched it much.  I'm assuming just as thick as you can go base gasket, obviously porting, trenched cases and cut domes for the 7 mil? Would like to learn.

Edited by Ayesully810
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The only musts are virgin porting , if they've been grounded on already the timings might not work with the stroke. Its really pick your poison, I've got stock cylinder 4 mills running 6.2 in the 1/8 in uncut stock chassis and 7mills going faster. The 7 was definitely easier to get the numbers out of but for what it is 4 mills run hard. The only thing you have to consider is the crank is a cpl Hundo more. I use forged  wsm crank webs and put all my own parts on it. They've been really holding up well but just like anything else its attention to detail on assembly 

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14 hours ago, sleeper06 said:

The only musts are virgin porting , if they've been grounded on already the timings might not work with the stroke. Its really pick your poison, I've got stock cylinder 4 mills running 6.2 in the 1/8 in uncut stock chassis and 7mills going faster. The 7 was definitely easier to get the numbers out of but for what it is 4 mills run hard. The only thing you have to consider is the crank is a cpl Hundo more. I use forged  wsm crank webs and put all my own parts on it. They've been really holding up well but just like anything else its attention to detail on assembly 

Carl i was hoping ud comment.  Just so everyone knows carl is doing my build this winter.  But yeah the cylinders that im sending to you are completely untouched as far as porting.  I was considering the possibility of going 7mil but im leaning more towards 4 right now bc there will be a little less involved. 

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If you have a good 4mil crank and all other supporting mods why not just build a 421 Serval?

Best bang for the buck, hands down.

Redline's Serval topend kit is only $1,450 and that includes free top case port matching.

http://redlineracing.biz/shop/4-10mm-serval-cylinder-kits/

The above numbers are not what I expect to see if I strap my Duner to a chassis dyno, and I'm perfectly ok with that.

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If you have a good 4mil crank and all other supporting mods why not just build a 421 Serval?
Best bang for the buck, hands down.
Redline's Serval topend kit is only $1,450 and that includes free top case port matching.
http://redlineracing.biz/shop/4-10mm-serval-cylinder-kits/
The above numbers are not what I expect to see if I strap my Duner to a chassis dyno, and I'm perfectly ok with that.


Wrong cyl for drag racing
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19 hours ago, JTmachining said:

 


Wrong cyl for drag racing

After riding a cub and my serval, id prefer to drag race my serval. If i could only have a banshee with drag ported cylinders, i would not own a banshee.

They arent wrong, they just arent IDEAL for some people's needs.

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After riding a cub and my serval, id prefer to drag race my serval. If i could only have a banshee with drag ported cylinders, i would not own a banshee.
They arent wrong, they just arent IDEAL for some people's needs.

OP is doing a drag bike. Serval isn’t a good option vs others
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Chris. I already have a 421 dune/ trail bike, my driveline setup on pump gas and stock carbs is quite satisfying.  Im set on using these stock cyls..

Carl, looks like we might be going 7 mil then.

Edited by Ayesully810
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