Jetting setup??

viperking

viperking

Active member
Joined
Jul 1, 2005
Messages
1,634
Age
46
Location
Boscobel, wi
can anyone verify my jetting setup? I am building a 780 viper with hauck pipes and i contacted hauck and they gave me these specs

162.5 mains
50 pilots
vent line to airbox unhooked
fuel screws 2 1/2 turns out
needles in the 4th groove from the top with one shim above and one below on the center and pto cylinders and both shims below the clip on the mag side.

Can anyone confirm these settings? also i only have two 50 pilots so would i be ok to go up to a 52.5 pilot on one side and 50's in the other two or go with 52.5 pilots all the way across? Any info would be great thanks
 

with the ventline unhooked, its gonna be awfull rich, but i didnt build it so i cant say, run what they tell you to run and adjust from there.
 
I does sound like a very good/safe starting point. I think 2-1/2 turns is too much tho w/50 pilots. Anyhow, run it like mrviper said, run it and tune it from there. If you wanna know if its too lean, its not. You'll be fine, provided no air leaks.
 
I would rather be safe then rebuilding lol, i will lean it out some if it is pig rich, i just wanted to make sure it was safe though. How much of a difference would it make if i hooked the vent line back up? When i was running it as just a 780 with no tripples the vent line was hooked up but they told me with pipes to unhook it
 
so after reading that essentially i could almost run 162.5 or 165 mains with the vent line hooked up on warmer days and then unplug it on very cold days to richen it up?
 
I do not own a Viper or a 780 so I have not tuned or set one up. From what I have read, I would caution you against running the Vents in the airbox on a BB Piped Viper as I have read that the airbox may be too restrictive for this setup and actually create a vacuum in the carb float bowls causing the sled to run lean at higher throttle openings regardless of how big a main jet you are using. Again this only food for thought from me and hopefully someone with hands on experience will chime in .

Bob
 
Ok, i will leave it unhooked then, i just thought i would ask, should it be hooked or unhooked on a viper that is just piped with no bigbore kit?
 
Viperking - You should re-read how the forced air induction setup works so that you are making a fully informed decision. Your carb. setup will be one of two scenarios. Either vented to atmosphere where air box pressure positive or negative has no effect on carburetor jetting behavior. Or yes plugged in to air box where vacuum and positive pressure effects jetting.
I personally like controlling the jetting circuits on my 780 without a the effects of forced air injection. It does not matter whether your a 780 or 700, ported not ported, bored carb, changed heads or stock as none of things matters. It will all depend on if your believe in the idea of forced air induction having effects on your jetting..
 
ok, yes after re reading it i do understand it better, essentially i believe after re reading the thread and as was stated above i will be very rich with 162.5 mains and the lines unhooked, i will be running with the lines unhooked and may possibly jet leaner once i get the sled going and can read the plugs. So if i understand it correctly the line plugged in works good for a stock setup but by removing it you gain better control over your jetting system?
 
Yes - do go with jetting to atmosphere. You control jetting and fuel flow.

What fuel are you using? What head setup? This is real important. How many cc's. What squish. Who's head.
 
Is this motor built already? Or is this still in the planning stages. The reason I ask is that depending on the head setup will dictate fuel requirements and jetting. Is this the Mr Viper motor? Let mrviper700 help you plan the head cc, squish amount, squish angel, based on 93 octane fuel you plan to run. When I ran my stock Yamaha head setup from CPR at 25.5 cc at .062 squish (compression 130 PSI) I was in the 152-155 area. Then after Mega power 24cc and .049 squish (150PSI) it required 162.5. Plan the head with Mrviper. Then learn how to read piston wash with the required piston dome light and learn plug reading 101 to get the most from your setup.
 
The motor was already built by hauck, i bought the sled and ran it last year with the single pipe setup, this year i pulled the engine and put it in a different chassis and added the pipes to it, the mr viper motor i have is an srx engine that i have not finished rebuilding yet, and mac your pm box is full i tried to reply to your last message
 
the viper technically donesnt have a real force air introduction. If you look under you hood the ports are on directly to the airbox. thier off to the sides. doesnt that help cool down the clutches and exhaust?
 
You must log in or register to reply here.


Back
Top