38mm carbs

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fusion 69

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Mr. viper, or anyone else for that matter, I'm puttin together a Mr. Viper motor, and was wonering if the 38's would be to big or should I get a set of 33's bored out?
 

well, what's this "mr viper motor"? a 780? a ported 700? probably would be best to ask the builder (mr viper), as he built it and should know the engine's carb requirements.
 
It's a ported 700, I geuss I should of asked if anyone is running the 38's with good success instead huh?
 
I have not run 38s on an SRX but I had TMX 38s on a Bender SX 800 BB for a couple of seasons. Although the sled was slightly quicker + faster with the TMX 38s, I was surprised how little difference the 38s made over the 33s. But when you are looking for every last bit of performance the larger carbs do work, at least on a BB engine.

Bob
 
Im running 38s in my bigbore and ive got to say i noticed a hell of a difference,When i was thinking of selling it last year i put the stock 33s back in and man did my sled loose alot of the pull it had with the 38s.Ended up keeping it and ofcourse i put the 38s back and am very happy with them.
 
If your running a BB on stock pipes the change from 33's to 38's is not huge. Add BB pipes or high rpm pipes and the added flow really helps!! Would think the same principals would hold true with a ported engine.
 
i run 38s on my 835 bb, they work great. they flow too much fuel on my ported motor 700. :nos:
 
thi sled only goes either 500' or 660' That was my thought is that they would be to much fuel for a ported 700 with stock exhaust. I'm probably just gonnago with a set of 33's bored. Next question is who does thebest carb boring in the industry? Thanks for all the replies.
 
i think aaen performance is into taper/straight boring carbs. dont expect huge gains though
 
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Larger carbs are mainly only going to see a increase on topend power. 38's will work fine on a fully cyl/case ported 700 for lake racing, long pull applications. For shorter drag racing type applications bored 33's to 35.5mm would result in a better application only in this engine's application because I already know what its specs are. In such a short distance the smaller venturi will keep the velocity of air higher.
If the engine was a "improved" type spec or "pro stock" spec, it would be using higher volume pipes and 44mm lectrons, and those carbs add BIG power increases to it, even with 700cc's

When having stock carbs bored, you dont just bore them straight thru. That is ,if you want them to work good at lower speeds because youll open up the fuel screw orfice in the throat and the screw will need to be further up in the hole to keep the fuel flow in check. Instead you want to offset bore them to the top slightly, this inturn leaves more meat and you open up the orfice less resulting in correct placement of the fuel flow screw taper. If you dont do this the screw will end up way in to control the fuel flow of the low speed circuit.
 
prostock 700 said:
what do you put in the lectrons for needles?
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all depnds on what mods are all done to the engine,but usually somewhere in the neighborhood of 6-2,-,7-1 needles, and about 1/2-3/4 turn out on the powerjet will get you up and running then fine tune from there.
 
mrviper700 said:
Larger carbs are mainly only going to see a increase on topend power. 38's will work fine on a fully cyl/case ported 700 for lake racing, long pull applications. For shorter drag racing type applications bored 33's to 35.5mm would result in a better application only in this engine's application because I already know what its specs are. In such a short distance the smaller venturi will keep the velocity of air higher.
If the engine was a "improved" type spec or "pro stock" spec, it would be using higher volume pipes and 44mm lectrons, and those carbs add BIG power increases to it, even with 700cc's

.
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What carbs would you recommend for a Price Performance 1000cc and JAWS pipes?

It currently has bored stock carbs and I am looking to make an upgrade this season if I can find some used carbs for the right price.
 
viper mtn said:
What carbs would you recommend for a Price Performance 1000cc and JAWS pipes?

It currently has bored stock carbs and I am looking to make an upgrade this season if I can find some used carbs for the right price.
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depends what your doing with it, if its for drags and want peak hp I would use a set of 48-50mm lectrons on it.

if its for trail riding or mtn riding I would use a set of offset bored 38's
 
mrviper700 said:
depends what your doing with it, if its for drags and want peak hp I would use a set of 48-50mm lectrons on it.

if its for trail riding or mtn riding I would use a set of offset bored 38's
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Mainly high mountain riding and this sled never seems to get enough air.

It has an SRX bottom end in a viper chassis.
 
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