5mil stroker jetting for a single 48 riva carb?

masterblaster

masterblaster

X-H2
Have a 5 mil stroker,stock bore approx 820 cc on stock elecs,lightweight flywheel,factory B pipe,ported pump with 15/18 solas with a newly added 48 mil riva power bomb carb,what would be the best jetting,needle and pop off and starting settings for the low and high speed screw settings

tried going with 155 main jet and a pilot 125 then 150 after that,tried both pop off springs in a 2.5 needle and seat one was 12 psi the other about 17 psi.
this freakin motor moves some air!! I cant get it to richen up for nothing. decent off the low end nothing very impressive and ok mid range and then runs out of fuel on top end and falls on it face,no matter how far out the high speed screw is out.
 
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THRUST

THRUST

ThrustInnovations.com
Location
royal palm beach florida
you will have to jet higher than that . the rivas usually run higher jetting than the novis i use . i would say you would be inthe range of 150 pilot and 165 main with the 2.5 at around your 12psi
 
masterblaster

masterblaster

X-H2
yz...what where your carb jets and settings? I tried the same jets in a blackjack 46 and got pretty much the same results,still lean hardly ever hit the pipe but for a sec,then back to mush,couldnt even really get it explosive out of the hole,it would hit the pipe a little in the midrange for just a few secs then fall on its face again

Virgin.. you think the pop off spring would make much diff?
 
Idok

Idok

F1pro
Location
Nations oldest muthaF+++kin city
yiou could always try taking the main jet completely out.........if the carb will handle it then that should take you onto the rich side...


also remember a few posts from back in the day where stroker motors woudl have upside down jetting, but not sure if that was with a single or duals..
 
THRUST

THRUST

ThrustInnovations.com
Location
royal palm beach florida
yz is set around 145 pilot and 155 main 2.3 ns but even his can change from carb to carb i hav ethe same set up ran closer to what i recomeended you . pop off makes a difference due to it being very hard to open ns you need really low pop off to get the fuel in there but you for sure need to go richer i run that set up on a 785cc big bore
 
masterblaster

masterblaster

X-H2
i tried these same jettings outa the riva on another 46 mil blackjack i have and it was a little better but basically the same result,I could feel it hit the pipe for a sec or 3 in the mid to top then it falls off again

Brian,I have the jets your talkin about on order,see what happens,just strange its so far outa wack with the jets I have,it doesnt feel even close?
 
H

HLS30

Location
surfcity
Sounds like there could be more than just a jetting issue. The falling off after 3 seconds sounds like lack of fuel to the carb or an air leak in the fuel line. I had similar problem and it turned out to be head o ring was just starting to go bad.
 
waterfreak

waterfreak

I had a vision!
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Location
s florida
HLS30 said:
Sounds like there could be more than just a jetting issue. The falling off after 3 seconds sounds like lack of fuel to the carb or an air leak in the fuel line. I had similar problem and it turned out to be head o ring was just starting to go bad.
Click to expand...

I second that. I running the same jetting on a single Novi 48 with a 6mm billet lamey stroker and I'm perfect.
I recommend you do a leak down test on your motor .
What is your squish and compression at?
 
masterblaster

masterblaster

X-H2
This motor was a high comp 205 setup for total loss,We have no patience for race gas and TL in the surf,so its runnin on another mrd 170 comp head slab I found and stock elecs with msd all known to be good runnin on the prev motor.
Squish could be making things more difficult,the motor has a 5 mill plate on the base,the mrd head that came with it was cut 3 mils for the stroke,the one i replaced it with was a tad more than that.
One thing i find strange is tuning it pushed up againt the bulk head,it goes soft and loses alot of rpm and hit when your braping the throttle,but if you let it idle for more than a 5 secs then grab WOT it freakin rips as long as you hold wot,but one sec off throttle and back on and it falls soft again and wont make it back to the pipe,unless you wait a few more secs of idle. but out in the water I cant get it to stay on the pipe at all.

maybe the fuel filter isnt flowing enough ill try elim that for a bit and see,even if the squish is a little off I dont see how it would cause this huge lean spot and running out of fuel up top
 
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masterblaster

masterblaster

X-H2
It had a mrd fuel injection on it before I put the carbs on and it hit HARD down low with that.One day when i have the time to machine a adapter for the intake to raise it,the MFI is going back on,it was sick,other than pulling air so low in the hull.
Does squish cause the motor to do anything different at wot than down low?
 
crammit442

crammit442

makin' legs
Location
here
masterblaster said:
This motor was a high comp 205 setup for total loss,We have no patience for race gas and TL in the surf,so its runnin on another mrd 170 comp head slab I found and stock elecs with msd all known to be good runnin on the prev motor.
Squish could be making things more difficult,the motor has a 5 mill plate on the base,the mrd head that came with it was cut 3 mils for the stroke,the one i replaced it with was a tad more than that.
One thing i find strange is tuning it pushed up againt the bulk head,it goes soft and loses alot of rpm and hit when your braping the throttle,but if you let it idle for more than a 5 secs then grab WOT it freakin rips as long as you hold wot,but one sec off throttle and back on and it falls soft again and wont make it back to the pipe,unless you wait a few more secs of idle. but out in the water I cant get it to stay on the pipe at all.

maybe the fuel filter isnt flowing enough ill try elim that for a bit and see,even if the squish is a little off I dont see how it would cause this huge lean spot and running out of fuel up top
Click to expand...

Squish may not be perfect, but that isn't your problem. A motor set up to get holeshots and still run out on MSD TL, race fuel, and big duals will never run anywhere near it's potential with the compromises you're making. When a motor is designed from the ground up to be a full race gas mod, certain porting decisions are made. The added compression, fuel, MSD TL, perfect pump/prop combo, etc. will allow awesome performance(better than most "freestyle" motors)with the more aggressive spec. Eliminate even one of the variables and it will not work as designed. Get rid of several and you will be right where you are. Good luck!
 
masterblaster

masterblaster

X-H2
im not looking for it to rip up top like a race setup would provide,I have the original ported pump and hill prop this motor came with. Without the total loss and high comp,it still hit like a truck with the mrd fuel injection.I am about to try some dual 48 full specs,after i try a large 175 main in these single setups just for comparison.
Ill take a down grade in performance for surf reliability hands down,its still WAY better than a ported out moded 701
 
Q

QJS

X-
Location
GONE
Have you tried putting a restritor in the return line?
Chris.
 
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