Needle/Pop-off Help

[munki63]

Is there a way to figure out what I need for pop off pressure or is it a guess and test?
You can hear my ski wants to go but it doesnt untill the rpm gets up then the screems(as in FFast not a bad thing) there is no hesation with the rpm it just doesnt go...

35cc
Mod B Pipe
Dual 44's

 

[SUPERTUNE]

Is the engine ported? If not ported, why are you running a mod chamber? Are you over over propped? Dual 44mm carbs can be tricky to get right also... Are your carbs aftermarket, OEM 760's or a mis-matched set of singles? Always get the pop-off the same with 2 carbs. A good staring point would be somewhere around 15-22 lbs, depending on how big the jets are. How about your pipe screws, are you adjusted to wet? How about too dry? Do you have a FCV (Jetworks valve) on the pipe stinger? Are you running a aftermarket flywheel? If so have you checked the timing with a timing light?
As you can see you could have a # of issues.
Chuck

 

[munki63]

engine isnt ported ran short on time and cash, factory b told me i would be fine with mod pipe, im running 9/15 hooker as suggested by improv, they are bored out munk 44, i havent tuned my pipe yet, i figured getting the carbs done 1st would be best yes i do have a FCV set at 3.5 psi stock flywheel

 

[SUPERTUNE]

What do you mean bored out 44's? Does that mean that they're 44 bodys with 46-48mm throttle plates? Post what jetting you have in there now w/what needle valve and spring.
You shouldn't need to tune the pipe just yet as FP sets them before they're shipped.
FCV is fine @ 3.5 lbs
Stock flywheel ok
Yes, start with the carbs....

 

[munki63]

130 M 120 P
ill pull the springs and look at them tomorrow, how do i tell the needle size
all i know is they were not OEM pull offs. they were bought from a jet ski shop and bored by jetworks

 

[Ericfox]

the size of the needle/seat is on the seat part.... pop it out and you'll see the tiny number on it...

 

[OCD Solutions]

If you don't already have the Mikuni manual you can download it as well as many other Yamaha manuals here. http://www.mediafire.com/yamaha/manuals

Do you still have the stock 38's or are those the carbs that came on that ski?

Did you get the parts i sent you for the SN?

 

[munki63]

Do you still have the stock 38's or are those the carbs that came on that ski?

Did you get the parts i sent you for the SN?

No I dont have the 38's

and I just got the SN parts yesterday

Thanks!

 

[munki63]

so i found the problem!!
a little back ground on the ski, I bought it off ebay in november, I never checked my compression...my bad with 35cc domes i was running 125psi and 150psi...i think i should be around 185 lol, I have 61X im putting in tomorrow thats ported....more power

 

[2XLR8]

The 35 cc should give you over 185 psi. Something is not right if its not ported it should be much higher than 125 psi. You need to find out why the compression is so low if indeed your gauge is accurate. It might be partially seized. Fix the compression problem before trying to fine tune the carbs.