big bore srx ???

madzx2

madzx2

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Osceola Wi
i am planning on building a big bore kit for my srx for next year. i noticed hauck sells a 73mm and a 74mm piston for the srx. the 73 being the 780 piston and the 74 being the 800 piston. so my question is can a stock cylinder handle that extra 1mm to make 800cc or would i have to buy a 780 sleeve from la sleeve and bore it 1mm? thanks for all the help!!
:2strokes:
 
I have 3 SRX bigbores. Two 780's and 1 800.. Looking at the cylinders I would never try to fit the 74mm pistons in the stock cylinder without a sleeve.. Not enough material left on the skirts to maintain any strength.. JMO though..
 
nevermind about the la sleeve i see they dont list one. i would still like to know where and how i could do this. is there a member i should talk to?

i just called hauck and they said thier 800 big bore is really a 780. but they do sell 74mm pistons that would make it a true 800. they said the 74s can be used in a stock cylinder but yes they get thin. so would the extra 20cc' make a huge difference? my cylinders are lake ported to begin with.

what does a 780 with lake porting make hp wise?
what would a 800 make with lake ported cyls? just a guess using stock carbs also? im looking to start grass dragging and ice running.
 
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so i called la sleeve and they do make a 780 sleeve. just waiting to hear if it can be bored to 74mm. so far cost of building 800 big bore is $795 for sleeves and pistons.
 
madzx2 said:
so i called la sleeve and they do make a 780 sleeve. just waiting to hear if it can be bored to 74mm. so far cost of building 800 big bore is $795 for sleeves and pistons.
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....and now pay a machine shop to bore your cylinders and fit the sleeves for you....probably $125 per cylinder. now have the sleeves bored to 800 (if they can be).....probably another $65 per cylinder. now, get the heads machined correctly for the big bore, or buy some. now sit down and get the time/area of the ports correct for the new bore and rpm that you plan on making peak power, and/or match to what pipes you plan on running. if you don't have the tools for porting, you'll need to spend about $600 to get basics needed. if you don't know how to port, or don't want to buy tools, or don't know how to come up w/correct durations and time/area values for the porting, then you'll need to send the cylinders out to someone else who can, which will = more $$$. the list goes on and on. IMO, just buy one already done, like pro116 pointed out. if you still feel you need to build your own, that's fine/cool too. nothing like saying you built it yourself. good luck on which ever route you choose. :2strokes:

forgot to mention that you'll need to machine your power valves or have someone else machine them for you.
 
thats what i would like to do is build it myself over a period of time. im in no hurry i have a pretty fast sled as it is. i have more time than money!
 
MY 780 I rebult 2 or 3 yrs ago. but you will need arctic cat 550 pistons relocate the ring pin using stock piston as guid
 
ok so after more research ive decided to just build a 780 next year. after seeing some dyno charts i think 780 should be enough.
 
Send your top end to Iantomasi here in Canada, they will port it, you will have stock like reliability and the same hp (160-165) as a 780.
 
do what u want. my 99 780 srx i had 4 8 yrs. 1,rebult .on yours the pwr val cut the spacer plat on jugs.the hotter stator 6 hp will put it at 165 to 170. easy trail or fastes lake SRX!
 
780srxgeorge said:
do what u want. my 99 780 srx i had 4 8 yrs. 1,rebult .on yours the pwr val cut the spacer plat on jugs.the hotter stator 6 hp will put it at 165 to 170. easy trail or fastes lake SRX!
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WHAT ARE YOU TRYING TO SAY???
 
After decoding the hieroglyphics, I think he is trying to say he prefers the big bore over porting, He thinks that is more reliable for trail riding.
 
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