44's vs. Full Specs 48's vs Riva 48's

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Freestyleriverrat

Guest
I am in the process of doing a genric comparison between a set of rebuilt OEM 44's with the chokes removed against a set of 48mm Full spectrum carbs and a set Riva 48mm power bomb carbs.

I say generic b/c this is just my subjective experience with these carbs. I am not a professional tuner, just an average wrencher and rider. I wish I had a way to do a flow test and stuff but if that were the case it would not be a generic comparison.

*The OEM 44 set up will be mounted on a R&D Manifold w/ v-force gen 1 reeds and reed spacers
*The Full Spectrums are mounted to a Full Spectrum manifold, sporting RAD valves and a reed spacer.
*I am going to see if I can get ahold of the full spec manifold and RAD valves, but if I can't I will mount the Riva's to the R&D manifold and v-force reeds. I would like the Full Spec manifold and RAD valves but it $600 :bigeyes:
 
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Freestyleriverrat

Guest
The motor:

Magoo Ported 61x 701 cylinder (82.5mm bore)
Ported 62t cases
ADA Head making 180psi (33cc)
Hot Rods Crank
B-pipe w/ mod chamber
Flow Control Valve
Lightened Stock 6m6 Flywheel
MSD Enhancer
 

junkman

nice weather=regret selin
im very curious to see what comes of this. I would like to know whos gonna be the champ :) Cant wait to hear what the outcome will be.
 
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Freestyleriverrat

Guest
I honestly don't think it is who is the best as much as it is a bang for your buck type deal.

If I can make a prediction, I would have to say that all the carbs are great. However, I think that the Riva and Full Spec carbs will not only flow more air and atomized fuel but do so more consistantly than the OEM 44's. That being said I think they will be easier to adjust, more responsive to adjustments and be more crisp than the OEM's, but by the narrowest of margins.

I am also a firm believer that the carbs are only as good as the tuner so we will see how I fair in this test :banghead:
 
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Freestyleriverrat

Guest
First off I have no idea how long this will take. I want to log hours on each set up, spend time tuning them so the throttle response is seamless throughout the rpm's and then go back and retest the set ups.

I am currently running the set of OEM 44's on the ski after running the Full Spectrums for about a week. The 48mm Full Specs are in the lead, although with more tuning on the 44's it could be close. I have been on other ski's with different set ups and 44's but they were not as clean as the full specs. That being said I feel there is still room for improvement with the full spectrums. The Full Specs were jetted with 135m, 122.5p, 1.8 n/s and 115g springs. High speed adjuster was ½ turn out and the low speed adjuster was 1 turn out. I did not really mess with them for 2 reasons : they are my buddies carbs and I did not want to mess with them and the ski ran really well with that set up, just a little rich.

What I plan on doing is tweaking the 44mm set up over the next couple of weeks. I am just hitting the water and have missed allot of good riding this year so I’ll be slacking a little on the comparison. Then I’ll start working on the Riva’s on my boat and see if squid will allow me to dial in his Full Spec carbs on his boat (almost identical set ups to my boat). So, simultaneously we will run the Full Specs and Riva carbs. I imagine squid and I will be riding allot so maybe I can get him to post his thoughts as well.

I was not planning on doing this comparison; just switch carbs to the 48’s. But since I had all these great carbs at my disposal I could not pass up the opportunity. Maybe it will help some guys/gals out when looking for carbs.

*If anyone has information that will help in this comparison please feel free to add to this discussion.

Pics: Full spec, OEM 44's w/o choke, Riva Power Bombs
 

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Freestyleriverrat

Guest
This is a nice summation of racing carburators I found off the GroupK website and I feel it is an appropriate way to start things off by letting the pros walk everyone through the fundimentals:

"Aftermarket pwc racing carburetors are (and always have been) relatively expensive components. For all the money that these carb makers have asked for their wares, few have offered much comparative data on the abilities of their carbs. For the money these parts cost, we believe that customers are entitled to a lot more information than they have been getting. It is our hope that this document marks the beginning of access to more information.

We have no doubt that the contents of this document will spark much controversy and discussion among high performance pwc owners, and some aftermarket carburetor makers...we invite that, and we think that’s great. We also suspect that there will be many folks that will want to refute the data in this document...we think that’s great too. We would like to submit that anyone who claims this data to be flawed, had better be willing to provide a more effective means of comparison, based on a more accurate and impartial means of testing. If a better means of testing and comparison exists we would gladly defer readers to it.

There are many "side issues" related to carb function that we intentionally did not include in this document. These issues are not unimportant, however they were unimportant with respect to our primary focus subject of full open carb signal. We would ask readers to strongly consider the writings of others, with respect to the many subjects we have not covered here. However we would also caution readers of others that might claim our omission of those subjects is an attempt to "hide something"...we hid nothing.

It has not been our intention to make this document the last word on high performance pwc carburetors...only the first word. Whatever subsequent information comes forward from other sources, there are a few conclusions that we feel are firm.

1 - Precise and responsive fuel metering is a function of carb signal, not airflow.

2 – Full throttle carb signal strength is a function of atomizer design.

3 - Big CFM numbers have questionable value, unless they are accompanied with big carb signal numbers.

4 - Carburetors with strong signal are easier to tune than carbs of weaker signal.

5 - Lean spots caused by weak carb signal CANNOT be altered or affected by richer jetting.

6 – For high performance pwc engines, good carburetor atomization is nice, but not mandatory.

7 – There is no such thing as a "best" flame arrestor for all applications. There can only be a "best" flame arrestor for a particular design carburetor, on a particular engine package."



*Check the above link for the whole artice on racing carbs*​
 
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Keith

Landlocked
Location
Nebraska
Do you know if the full spectrums came with a 2.0 and a 115 originally? Or is this something that the owner changed himself?
 

RMBC Freeride

Vintage
Site Supporter
Location
Pueblo, CO
Freestyleriverrat said:
*The Full Spectrums are mounted to a Full Spectrum manifold, sporting RAD valves and a reed spacer.

Were you actually using a reed spacer w/ the full spec/boyesen manifold? Because that manifold is built with the reed cages recessed, eliminating the need for a spacer plate??? Just curious?
 
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Freestyleriverrat

Guest
RMBC Freeride said:
Were you actually using a reed spacer w/ the full spec/boyesen manifold? Because that manifold is built with the reed cages recessed, eliminating the need for a spacer plate??? Just curious?

No, it does have a reed spacer built in so I just mentioned that it had a reed spacer.
 
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Freestyleriverrat

Guest
I really feel that, although you can make the OEM 44's hit nicley all around and maybe peform just as well as the Riva's and Full Specs, the Riva's and Full Specs still are better carbs by design. I think the design improvements aid in fuel atomization, throttle response and overall power over the stock carbs.

Now I did not get my 44's dial in fully b/c I recieved my Riva's and went ahead and put them on. B/c of that I am not going back to the 44's :biggrin: Power and response wise the ski is running better than it did with the Full Specs but that can be attributed to a couple of factors like: the rad valves on that set up had over 4 years of use on then and one was slightly cracked, the carbs were running a little rich compared to the mostly dialed in Riva's and the N/S are probably overdue for a change in the Full Specs. The riva's are bing runon a R&D manifold (60 bucks used) and a set of V-force gen 1's (120 used only once by the previous owner)

Bang for Your Buck

#1 OEM 44's
Average for a set is about $200-$400. Definatly the winner in this catagory are the OEM dual 44's. If you take the time to properly tune this setup you will be very pleased with the results.

#2 Riva Power Bombs

I have about $700 in the used Riva's. New ones go for $879. Great performance and throttle response. Very comprable to the Full Specs but b/c of the factors listed above a true comparison could not be obtained. Whole set up on the ski adds up to about $900 (manifold, reed spacers, carbs and reeds) as opposed to about 1300 if everything were new

#3 Full Spectrum

Price new for the set up is about (I have heard, correct me if I am wrong) $2100-2500 or $1500 for the carbs alone. Hits nice but I don't think they are 2X better than the Riva's from a price of performance stand point.

*** I think allot of the cost of the full specs is the attention to detail and fit and finish of the carbs. Ed spends the time to address even the smallest details and he flow tests his setups for that added level of precision. All that time, effort and expertise comes at a price***
 
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