Need Pop Off Pressure Explained

[JAYSONFLYNN]

SeaDoo GTI 717 Dual Carbs:

Installed new factory Mikuni carburator kits. Kit came with two springs, thanks to this site found to use taller spring. Yes, need to invest in pop off pressure guage, so just guessing at what's going on here. Throttle has to be feathered to half way to keep from stalling, then takes off and the 1/2 to WOT is great. Let off throttle and will come back to idle, but then same procedure to get it back to speed. Low speed circuit set to 1 1/4 out.

Would switching to the smaller Mikuni factory spring be worth a shot?

Could someone familiar with pop off pressure please explain more in detail the function of how it factors in to the way it runs?

Thanks

 

[Legacy37]

Did you replace the needle and seat ?

 

[PorknBeans]

https://www.mikuni.com/pdf/sbn_manual.pdf
Pop Off content starts on Pg. 14

 

[Legacy37]

My 97 gti did the exact thing you are describing, Needle and seat fixed it

 

[JAYSONFLYNN]

Yes, also replaced needle and seat with this kit from Bay Area Powersports. Apparently these are 1.2mm, not the recommended 1.5

https://www.amazon.com/Mikuni-Twin-...t+Sea+Doo+HX+SPX+GTI+XP&qid=1597884048&sr=8-1

 

[JAYSONFLYNN]

Thanks for the Mikuni manual link, great info!

Any suggestion on where to order a factory needle and seat from?

 

[racerxxx]

You don't use any of the springs that come in the kit. Put your original back in. They should be dark in color not silver.

 

[racerxxx]

The 96 GTI calls for the 1.2 n&s NOT the 1.5. the 97 gets the 1.5 because that year is only a single carb.

Look at the chart, if there is no part number listed for the PTO carb that designates a single carb.

http://www.seadoosource.com/carbreference.html

 

[racerxxx]

Those needle and seat are NOT genuine Mikuni. They're wsm aftermarket junk. You have to be really really really careful buying from Bay area. They're crafty with their wording. I've see it for years and refused to buy from them. They do sell genuine stuff but also still aftermarket. What you paid for a pair is what 1 will actually cost you.

Post the link to the carb kit you bought. Did it come in a Mikuni package? If it didn't, it's probably not genuine. If you bought a la carte from OSD they will not be in a genuine Mikuni package but you have the choice of genuine or aftermarket there to, but they're clear about which you're buying, they're not using tricky wording.

 

[racerxxx]

Here you go.

Did your kits arrive in the packaging shown?

School down for the viton needle and seats. You need the 1.2's

https://osdparts.com/index.php?main_page=index&manufacturers_id=5

 

[racerxxx]

I used to use a pop off gauge I built for years. Bought the real deal Mikuni and never looked back. It's such a work of art, I no longer fumble and it's dead accurate. Not cheap but it's the best hands down.

https://www.ebay.com/itm/254488676801
I have the 0-60 version, which is I think the one in the link.

 

[JAYSONFLYNN]

This is the exact kit believed to be Genuine Mikuni. The first kit bought was less than $30 and came in brown envelopes.

https://www.amazon.com/gp/product/B01BHI8G68/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

 

[racerxxx]

Ok, those are good. But, do not use the springs in those kits. You have to use the original springs.

 

[racerxxx]

Did you follow the sticky on the carb rebuilds? It's a wealth of knowledge

www.seadooforum.com/threads/the-seadoo-carb-rebuild-thread.89199

 

[JAYSONFLYNN]

Put the stock pop off springs back in and it fixed the issue. Appreciate the help!

 

[racerxxx]

Excellent! Amazing how a little spring can screw you over.