Shiny silver 115g spring on 07 superjets

Ericfox

Ericfox

Do it twice?That's DooDoo
Location
Akron area --> OHIO!
In case you happen to be doing your mods on an 07 superjet... and maybe other very recent years--> the stock 38s on 2007 superjets have shiny silver 115g springs... not gold... dont be confused...

I thought maybe they where just 95g springs until I tested the popoff and got 51 psi.... I am going to keep the shiny silver springs in with my new setup to see how they run, but I may end up going down to 95g springs... not sure yet...
 
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Mike W

Mike W

Infidel
Location
North Florida
Ericfox said:
In case you happen to be doing your mods on an 07 superjet... and maybe other very recent years--> the stock 38s on 2007 superjets have shiny silver 115g springs... not gold... dont be confused...

I thought maybe they where just 95g springs until I tested the popoff and got 51 psi.... I am going to keep the shiny silver springs in with my new setup to see how they run, but I may end up going down to 95g springs... not sure yet...
Click to expand...

I ran 115 gm springs in my last ski (which is close to my current setup) just to see how it would run with high popoff and it ran like crap. 51 psi is way too high. I think my current popoff is closer to 40-42 psi.
 
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Ericfox

Ericfox

Do it twice?That's DooDoo
Location
Akron area --> OHIO!
cool... was hoping someone might chime in with a little input... I'll grab up some 95g... I had a bad feeling I would be buying more crap... cant wait to see what shipping on 2 frickin springs will be lol... I'll have to look around to see if I have any first.... but I dont think so....
 
Mike W

Mike W

Infidel
Location
North Florida
I just had to bit the bullet and pay out the ass to ship two springs and two spring arms so don't feel bad.

If I remember correctly, it wouldn't hardly run with the 115 gm springs.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Ah....that is very strange.
Unless those parts are non-Mikuni, they are 95g springs that are not very accurate.
As far as I know, Mikuni supplies those (complete) carbs directly to Yamaha. That means they are 95g springs - even though they are wildly out of spec.

I have found this quite a few times, with different springs
 
Ericfox

Ericfox

Do it twice?That's DooDoo
Location
Akron area --> OHIO!
I got about 51 psi consistantly. I was told I should get between 48-52 for the stock popoff. That is if your set came with the 115g... I dont know for sure, but I think some skis used to come with 95g in the 38s if I remember...
 
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Foximus

Foximus

CFL Cheapass.
Location
Oviedo, Fl
not that my motor was stock 07 material, but when I started tearin everything down this month and redoing everything, There were gold springs that were cut down in my 38s.

The pop off went to 60 psi and had not even popped yet.... I thought that seemed a bit rediculous. I dont know what it would have popped at but I didnt want to rip a diaphram or something.


I ended up using black .65's to get the pop off down to exactly 30psi. The one time I rode it, it worked a Sht load better than 60+ psi, that is for sure.
 
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Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Um.....those are 38mm carbs. The air velocity through those relatively small orifices (compared to the next size up, a 44) is quite large.
It needs high popoff to work right with that high air velocity.
Popoff isn't an absolute value that transfers from one setup to the next.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
His carbs are typically 48mm. MUCH lower air velocity.
Additionally, his internal circuitry is a bit sensitive to having just that popoff pressure. That's how he builds them.

The vacuum pulled on the popoff diaphragm is directly related to the air velocity through the carb throat.
With 48mm carbs, the intake air has to go through a 36.2 cm^2 opening.
With 38mm carbs, it has 22.7 cm^2 to work with, a mere 63% of the 48mm figure.
 
SUPERTUNE

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
AND...all the new Mikuni rebuild kits now are coming with BRIGHT SILVER (cheap chrome look) springs and they are 115 springs! I think that Mikuni had a manufacturing supplier change.
 
vjhardcore

vjhardcore

Ride It Like Ya Stole IT!
Location
Toronto, Canada
Wha? wha? wha?

Ericfox said:
definately 115g and shiny silver... must be just a new oem thing... it is a bit strange
Click to expand...

Just got my 07 last fall - no motorwork other then Pipe. I'll have to read this again, but I have no idea what you guys are talking about? How can I get in on it? Should I be making a change? And Mike - Didnt you sell that thing yet - Ha.:usa:
 
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