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664 vs640


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#16 sc4me

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Posted 29 April 2012 - 08:44 PM

PUT A TRIPLE IN IT

#17 TT670

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Posted 29 April 2012 - 10:10 PM

Theres more to big boring the 500ss/600 engine than opening the bore and tossing in larger pistons. Every big bore Ive seen on them also uses a shim under the cylinders to suit the change in piston height and then a custom head to match.

#18 whirli

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Posted 30 April 2012 - 11:17 AM

What types of HP are people seeing with these big bores, 130-135?

#19 revx440HO

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Posted 30 April 2012 - 11:21 AM

RKT 664. Just get kelsey to cut domes for your desired octane.

#20 marc_brown98

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Posted 30 April 2012 - 12:54 PM

RKT 664. Just get kelsey to cut domes for your desired octane.

Compare the jugs of a ported 662/664 to a set of overbored stock jugs, there is much more going on..Every single port is touched and changed. Plus the 662 motors use a custom base gasket/shim to get proper exhaust port timing. The RKT piston is machined and the piston is a flat top vs a more crowned top style piston. Without the correct porting and pipe these motors fall on their face at 8100-8300.
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#21 one_fast_x

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Posted 30 April 2012 - 01:51 PM

Rk Tek doesn't use a shim, but the pistons aren't the same height as the stock pistons, TT670 couldn't be more right... It's not slapping pistons in, you have to port the engine for port timing and hp, and the head needs to be deck and or squish band cut to allow the right compression ratio... There.is a lot more R&D that goes into building a BB than boring your cyls. Out and slapping a piston in because you grenaded it...
Then you deal with the pipe... With all that extra air your pipe might not be loose enough to handle it, thus you will burn it down, now add fuel... How much and where?
You are paying because all of this research is done for you already... U don't have to buy 3-4differnt sets of pistons, port an engine 3-4 Times, rent out a dyno for a week... Ect... See where I'm gettin with this??
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#22 2001mxzlongtrack

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Posted 30 April 2012 - 07:06 PM

makes sense...it was more of a wondering thing than just trying to cut corners. R&D cost what it does for a reason. im not bashing that. thanks for the info

#23 revx440HO

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Posted 30 April 2012 - 09:04 PM

has anyone scourced their own pistons and did their own big bore instead of paying out all the cash? If you can get buy with 670 pistons at .040 overbore or 650 kawi pistons, wouldnt all thats needed is a bore to fit them correctly? then put on a custom head, and for the die hards a diy port job. i guess this question could be for marc, would the race logic sport port kit for the 500ss work on one of the above overbores, added with a head and be ok? if we could figure out a way to do our own bigbores, we could cut cost and have the satisfaction of doing it ourselves. just thinking i guess, thats all...

Yes. It has been done. I did the same thing back in 2000. By the time you figure in all the extra work/parts it is NOT cheaper. I have done alot of one off BB builds. I still tinker around with building some of my own designs.
When it comes to my primary trail sled....RKT. Pull an go. Had my 827 for 6yrs. Now moved on to the 860r.

#24 marc_brown98

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Posted 30 April 2012 - 10:44 PM

the 662 from RKT uses a spacer aka shim. It's listed right on the parts list unless Kelsey has changed the spec on the motor. :)
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#25 fessie

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Posted 01 May 2012 - 01:56 PM

The reason for having it built for 87 octane is reliable fuel you never know i always pump midgrade when i am empty and if we stop at a station and i still have fuel i top off with premium season is to short to burn down i wouldnt be happy




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