760 and dual 38 issues

superhondaz50

superhondaz50

Location
Fort Mohave, AZ
I sold my dual 48's and downgraded to some 38's. Fully rebuilt with winderosa kits, new genuine mikuni pop off springs, jets and needle seats. Setup has stock flame arrestors with 2 screens removed and brand new carbon tech reeds. The ski runs like utter craap. Cuts out at all RPM, almost likes its starving or hitting a rev limiter, but if I stop for a few minutes it has trouble starting due to it being flooded. I have no clue whats goin on as I run the exact same setup in my other skis and its perfect. Any ideas?
specs are:
72.5 low
135 high
95g spring
1.5NS
cold fusion internal fill
ported 760 with b pipe, h20 designs waterbox, 170PSI, MSD enhancer, newmiller flywheel.
Thanks
 
Blue

Blue

Judging your cheapness
Location
St Cloud Florida
Yes with bpipe run 75 on low jet also test ur popoff. Possibly its to low maybe has the wrong springs in it?? Popoff psi test will take all the guess work out of trying to figure it out.


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Blue

Blue

Judging your cheapness
Location
St Cloud Florida
Is it a ported motor? Are the reeds stock? And which airfilters are you running stock or aftermarket? Jetmaniac has new guages in stock if u cant find used.

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Blue

Blue

Judging your cheapness
Location
St Cloud Florida
I would go with
75 low
140 main
115 gram springs
And start the needles 1 turn on low and 1 and a half on the high. And if you test popoff it will be close to 50 to 55 psi. If its to rich adjust the high in a 1/4 turn. We run this setup alot and it works fine. I typically like to go closer to 43 psi popoff but thats with aftermarket FA.

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JetManiac

JetManiac

Stoked
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Vendor Account
Location
orlando
Did you check the return restrictor in the slave(front) carb plate? If it is clogged then fuel cant return properly and it will flood the carbs with too much fuel. Also dont recommend using Winderosa kits.

As Blue said your jetting is probably too lean, but popoff is a little low for oem f/a. The mikuni 95g springs with 1.5n&s are supposed to be 43, but usually test 30-33ish.
 
superhondaz50

superhondaz50

Location
Fort Mohave, AZ
Ya, when I rebuilt them I cleaned the restrictor with a guitar string. I had winderosa kits laying around so I used them. They seem to always work well on my skis but I agree OEM kits are better. My 62t with 135/75/115g/1.5ns and dry pipe just about tore my arms off it hit so hard which is why i'm stumped on this ski, almost identical setup, just 60 more cc's. So do you think I'll be more in the ballpark with the 140/75/115g combo?
 
JetManiac

JetManiac

Stoked
Site Supporter
Vendor Account
Location
orlando
Alot depends on the rest of the setup. How extensive and what kind of porting, timing, pipe, prop, etc. If porting is done wrong, then it can sometimes ruin performance. Did you run this motor with before with the larger carbs and it ran good? If so, then you know it is just a problem with the dual 38 rebuild or setup.
 
superhondaz50

superhondaz50

Location
Fort Mohave, AZ
Everything on the ski;
-Newmiller freestyle ported 760, fresh bore, prox pistons
-mod b pipe
-h2o water box
-newmiller flywheel
-newmiller 170psi head
-carbon tech reeds
-msd enhancer
-solas 144 pump with 10/16 hooker
-dual 38's stock fa
-stock timing
 
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