Riva Powerbomb Jet suggestions...?

Peebles

Peebles

Location
Reno, NV
Ski Set-up:

Stock 61x
Wet-jet intake/Ported with cages and boysen reeds
B-pipe
Single RIVA POWERBOMB Carb

Im riding the ski at 4000ft. It currently has a 130 main, 117.5 pilot, 115g spring. Doesnt have the response I was looking for and dies off a lot up top. It also doesnt like to run at full throttle. RIVA suggested I start with a 155 main and a 160 pilot but that seems a little too big for me especially since Im at 4000ft...... ANY help would be greatly appreciated! Thanks guys!
 
S

sflsurfrider

all of the numbers i have been getting for my new riva PB have been pointing upwards in the numbers of 155/180 with the lowest possible popoff w/o cutting springs or bending levers (2.5/65g)

i havent tried thiat jetting yet, but based on my only ride w/ it, it seems like something COMPLETELY different might work. its only jets. theyre cheap. im going to try it.

peebles, keep in touch. we might have to bounce numbers of of oneanother to get our carbs dialed.

it sucks that riva makes such a killer carb, but really knows nothing about it.

good thing jets are cheap.
 
Peebles

Peebles

Location
Reno, NV
Ok. Best combo for tonight was a 155 main and a 120 pilot. Responce is still pretty bad but once your in the sweet spot it pulls good. Still doesnt like to run at wide open throttle for too long though.... I'll have to figure out why its got a delay then it should be better aswell.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Is there a 60 main jet inserted into the fuel return line?
If you don't have a return line restrictor, your jetting will be very large and the ski will not run right. That carb must be run with a restrictor or you'll be chasing your tail forever.
I would check this out pronto, as that might well solve your problems.
 
S

sflsurfrider

Matt_E said:
Is there a 60 main jet inserted into the fuel return line?
If you don't have a return line restrictor, your jetting will be very large and the ski will not run right. That carb must be run with a restrictor or you'll be chasing your tail forever.
I would check this out pronto, as that might well solve your problems.
Click to expand...

matt, arent these carbs restricted internally already?
 
waterfreak

waterfreak

I had a vision!
Site Supporter
Vendor Account
Location
s florida
Peebles said:
Ski Set-up:

Stock 61x
Wet-jet intake/Ported with cages and boysen reeds
B-pipe
Single RIVA POWERBOMB Carb

Im riding the ski at 4000ft. It currently has a 130 main, 117.5 pilot, 115g spring. Doesnt have the response I was looking for and dies off a lot up top. It also doesnt like to run at full throttle. RIVA suggested I start with a 155 main and a 160 pilot but that seems a little too big for me especially since Im at 4000ft...... ANY help would be greatly appreciated! Thanks guys!
Click to expand...
that alone will get make the jetting different from any set up at sea level.

What size needle and seat are you using? You should have a good pop off gauge to properly set your pop off where you want it and also make sure that your needle and seat are not leaking and is holding pressure
 
Peebles

Peebles

Location
Reno, NV
Ok. I'll check that asap. Which line is the return line? Im assuming the restricter creates more fuel pressure?? Im running a 2.5 needle and seat and it is holding pressure. Biggest thing that is bugging me right now is the delay between when I give it gas and when it actually picks up and gets into its power band.....Thanks for the info so far guys..


Matt_E said:
Is there a 60 main jet inserted into the fuel return line?
If you don't have a return line restrictor, your jetting will be very large and the ski will not run right. That carb must be run with a restrictor or you'll be chasing your tail forever.
I would check this out pronto, as that might well solve your problems.
Click to expand...
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
sflsurfrider said:
matt, arent these carbs restricted internally already?
Click to expand...

The Powerbomb I purchased in Spring of 2007 was not restricted internally.
I didn't know it needed a restrictor at first, and it ran very badly.
I jetted up to 130/160 and still found response lacking, with flat spots.
I put in the required 60M restrictor, jetted down to (whatever it was) and it was perfect.

Which line is the return line? Im assuming the restricter creates more fuel pressure?? Im running a 2.5 needle and seat and it is holding pressure. Biggest thing that is bugging me right now is the delay between when I give it gas and when it actually picks up and gets into its power band.....Thanks for the info so far guys..
Click to expand...
That delay is exactly the problem I had before using a restrictor.
Return line is the top line on the carb.

that alone will get make the jetting different from any set up at sea level.
Click to expand...

Not in my experience with the Powerbomb.
I have used it at sea level and at 3,000 ft without any changes.
Any changes that may be necessary should be at the adjuster screws only.
 
Last edited:
orangefinger

orangefinger

Location
Reno,NV
5500 Feet !!!

All skis had to be changed to 1,5 N/S, always running way to rich cause of lack of air
Jeeting > i would leave I am running blaster with same set up also ported
140 main 125 low 95G Spring !!!

high screw 1
low screw 1
 
Last edited:
Peebles

Peebles

Location
Reno, NV
Ok. So I just shove a 60 main jet into the return fuel line right out of the carb? Seems easy enough..... I'll give that a shot and see what happens.
 
showmepro1200

showmepro1200

ISJWTA Member #007
Location
Jefferson City, Missouri
Peebles said:
Ok. So I just shove a 60 main jet into the return fuel line right out of the carb? Seems easy enough..... I'll give that a shot and see what happens.
Click to expand...

When my son (Experimental) and I did his machine I found that I could screw the pilot jet (restrictor) right into the return nipple on the tank itself. Worked like a charm. And btw this was on a dual Riva Pro-Series carbs (pre-Powerbomb??) setup.
 
Peebles

Peebles

Location
Reno, NV
Was out at lake shasta over the weekend and I think I found my problem....Guy who had the ski before me stripped the exhaust manifold threads out and all 3 bolts where loosening over time. HUGE exhaust leak. Hopefully I can make some jetting progress now....
 
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