Carburetion

[Gary pope]

Can somebody give me some assistance, I have posted this question a couple different times with no response so I’m gonna try it one last time. According to the manual the pop off pressure for my 95 Sea doo speedster with the twin 657X motors states that it should be between 17 and 21 PSI, now when I read online on some forums I get conflicting stories some people say it should be in the mid-20s to lower 30s, which one is it?

 

[snikwad003]

The one in the manual is your best bet. Seadoos stock settings are pretty spot on

 

[Gary pope]

OK but it seems to me that roughly 19 pounds is low, isn’t that going to make it flood?

 

[snikwad003]

I doubt it will leak if it's in the specd range

 

[mikidymac]

You can also look at the mikuni spring and seat chart for example if it has a 1.5 needle and seat and a 95 gram spring the pop off has to be 43 psi

 

[Gary pope]

OK so I pulled the carbs back off of it because when I was trying to start it I’m pretty sure it was following the plugs out because I could smell gas really really bad. I pulled the carbs off and I am assuming the gold part is the needle valve, it says 1.5 on it. I tested it again and it was popping off at right around 18 . So should I disregard the manual, because it says the pop off should be between 16 and 21 however according to the Mikuni site that you listed my 1.5 needle valve size the lowest you should be is 32 PSI.Attached are the sea, the arm in the spring that I am using

 

[Gary pope]

And how in the hell do I tell what spring is what

 

[mikidymac]

First off your needle arm is really bent in the picture. The two sides should be parallel with each other. THat is why your pop-off is so low and it is flooding. With it bent that much there is no way it is passing the leak down test with the diaphragm and cover on.

Here is the chart for measuring the springs.

 

[Gary pope]

OK now we’re getting somewhere, in the manual it states that you can bend the arm a little bit so I think I’m gonna just go ahead and just say screw the manual then. I’m assuming I can just straighten this out and make them flat again?

 

[mikidymac]

By a little bit they mean 1-2mm so almost nothing but it does make a difference when trying to get pop off exact on dual carb models.

 

[Gary pope]

I’m assuming I can just straighten these ones out then?

 

[Gary pope]

Is there a kit I can buy that has all the different sizes in it? Also what size do you recommend I use?

 

[mikidymac]

Well, the spring that your engine uses is part number 270500242 but it is no longer available and only used on the 657X engine in 1995. Given the lowest pressure you can get on a 1.5 seat with a standard spring I would suggest the 65 gram. That would give you 32 psi and the range for your engine is 19-35. I don't know if that 270500242 was a special spring made just for seadoo or what though.

 

[Gary pope]

That is the size motor that I have, 657X in my speedster, so I guess I will put the 65 g which is the shiny silver Spring in them and try that. So you’re saying that I need to get these carbs all synced up to 32 PSI for pop off?’ Spring in them and try that. So you’re saying that I need to get these carbs all synced up to 32 PSI for pop off?. This is all confusing to me because in the manual it says 16 to 21

 

[mikidymac]

I am pretty sure the manual is wrong. The 1994 650X shows the 1.5 needle with a 16-21 popoff using the 270500130 spring, which is a 95 gram spring so there is no possible way for a heavier spring to provide a lower pop-off. If you look at Mikuni's own chart there is no way you can get that low of a pop off with a 1.5 needle and seat.

I would try yours with the arm flat with the carb body, a razor blade works for that and a 65 gram spring.

 

[Gary pope]

So this could be my problem why I have been having issues with it flooding out all the time then I’m assuming
I’ll try the 65 g Springs, flatten out the arms, and then tested. The pop off should be 32 is what you’re saying correct?

 

[mikidymac]

All correct.

 

[Gary pope]

OK so I just put a 65 g spring in it in it is popping off at 22, I put a 115 g in it and it popped off right around 43 which one should I use

 

[mikidymac]

The 65 just like i said.
You also need to make sure it will hold 10 psi when you put the cover an diaphragm back on.

 

[Gary pope]

OK but when I put the 65 in it pops off right around 22 though

 

[Gary pope]

OK I got the 65 g spring to pop off just before 32 PSI, is this been in the arm OK? I had to bend it in order to attain the 32 PSI

 

[Gary pope]

Also can you tell me just to make sure that I am hooking this up right? The hose on the left goes to my leak down tester and all I do is plug the right-hand side

 

[mikidymac]

That arm looks way too bent the other way now. I'll post a picture of a new one when I get home.

Your tester looks fine.

Go to post #7 in my carb thread below and you will see where I hold a razor blade across the body to verify the arm height.

 

[Gary pope]

I just don’t get it. I tried the 65 gram spring and it was popping off to low, the 115 gram spring was too high, around 43..

 

[mikidymac]

With a new needle and seat, the correct springs and a lever that isn’t bent it will pop at the correct pressure. What’s yours at?

Not sure why you are bothering with the 115 spring?