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8 Hp Briggs Upgrades


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#1 superspeedex OFFLINE  

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Posted July 22, 2013 - 07:21 PM

i have and 8 hp briggs on my speedex but what  all should i do to make it run better and yet still be realiable its bored .020 over and valve and guides have been done  i was going to polish it up and cut the "eyebrows "  in it regrind the valves but what else should i do to compete with the 2 cylinders


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#2 LilysDad OFFLINE  

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Posted July 22, 2013 - 07:41 PM

Better carb? reground cam?


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#3 superspeedex OFFLINE  

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Posted July 22, 2013 - 07:52 PM

Also would i gain anything from porting and polish my carb and intake??


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#4 superaben OFFLINE  

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Posted July 22, 2013 - 08:42 PM

If you were to really want my opinion, I would say buy a brand new carburetor NOS.  There's nothing that makes an engine run better, unless you have a guy who really knows what he is doing rebuild it.

 

Ben W.



#5 larryd OFFLINE  

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Posted July 22, 2013 - 08:42 PM

Every little bit helps

larryd

#6 superspeedex OFFLINE  

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Posted July 22, 2013 - 08:48 PM

Yea i need to do something to support the higher rpms like 4000 to 4500 but cant find better valve springs cause they only make performance springs for the 5 hp



#7 cookiemonster OFFLINE  

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Posted July 22, 2013 - 08:50 PM

I'm not familiar with the classes you run but standing a briggs 8hp against any twin cylinder may be the knife at the gun fight.  I'm not belittling the briggs, but just being honest.  When I was a kid, I only had what we had to work with and I tried to compete with an 8hp briggs bolens in a 10hp class and later a 14hp Kohler bolens in a 16hp class... And I came up way short each time.  No regrets, but I knew when to pack it in. Sure, we could've done better with an investment of time and money in it... but guys were putting time and money into their bigger engines, too.


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#8 superspeedex OFFLINE  

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Posted July 22, 2013 - 08:58 PM

Yea i really want to keep mine looking original and being i have skinny tires i spin out in dead sled and there isnt really nothing to win except pride i was competing againdst an older cub on turbo blue but i am going to make wheelie bar and call it good



#9 Dieselcubmike OFFLINE  

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Posted July 22, 2013 - 11:51 PM

I agree with dean as I came from the same background but I had pit my sears up against the cub boys :smilewink: I mean there is some engine work you can do but its not really worth the time or investment in my honest opinion. I never seen a speedex pull before either? Youll need wider tires and a better class to run in because its not even a close fight to have you run against the vtwin motors.



#10 LilysDad OFFLINE  

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Posted July 23, 2013 - 07:05 AM

Also would i gain anything from porting and polish my carb and intake??

Yes. It doesn't have to be a mirror finish, though. Use your gasket and match the port shape to the carb.



#11 Bruce Dorsi OFFLINE  

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Posted July 23, 2013 - 08:10 AM

Yea i need to do something to support the higher rpms like 4000 to 4500 but cant find better valve springs cause they only make performance springs for the 5 hp

 

The valve springs can be shimmed to gain more spring tension, if that is what you have in mind.

 

You just need to make sure that the coils do not close completely (spring bind) when the valve is at full lift. 

 

You may also be able to adapt springs from a different engine.


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#12 superspeedex OFFLINE  

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Posted July 23, 2013 - 08:15 AM

ok I am thinking bore the carp might remove choke but then bore the intake tube or modify it so its not a 90 degree angle  skim the head cut eyebrows port and polish intake and exhaust and mabye weld a couple beads of aluminum on the head to bump up compreesion also what would i gain if i put a heavy flywheel on it like 10lbs more lugging power but would i loos the ability to rev up quicker??



#13 Dieselcubmike OFFLINE  

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Posted July 23, 2013 - 10:06 AM

If you put a heavier flywheel on it'll take a little longer to wind up but since its a larger rotating mass it will help keep power on your top end. But be warned once you start getting under a heavy load its not going to save you. I would get a billet steel flywheel made from either Lakota racing or Midwest supercub. 



#14 LilysDad OFFLINE  

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Posted July 23, 2013 - 10:16 AM

 what  all should i do to make it run better and yet still be realiable

Maybe I'm just assuming. Are you going to pull with it or just a hopped up yard tractor?  Some folks, like me, just want a street rod that cuts grass. If that is the case, some things like boring the carb would not be a good thing. Same with the3 billet flywheel. You wouldn't have any cooling.


Edited by LilysDad, July 23, 2013 - 10:20 AM.

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#15 superspeedex OFFLINE  

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Posted July 23, 2013 - 10:34 AM

Well i want to plow and then pull at plow days as far as realiability goes but i was going to make a heavy flywheel that goes on the pto side of the engine between the pulley and engine but wont the more waeght on the crank wear bearing out faster?  it probaly would only wiegh between 5 and 10 lbs so would that be noticable?  like lugging it down when plowing?