Other what would a bad check valve on a carb cause

[zwaysfs]

I decided to rebuild my carb today. The first rebuild since I bought it a year ago and the check valve (part number 12) was bent backwards so it couldn't seal. What would this cause in the motor? The other one was fine. They are NOVI 48s

 

[smoofers]

The check valve is part of your carb's fuel pump. Bad check valve = poor fuel delivery.

 

[surfjunkie]

i read the troubleshooting page of the mikuni manual and none of the symptoms listed bad check valve as the reason. i have heard they cant be creased and have to seat against the carb body flush. no high spots.

but what it does if they are bad.... i dont know

 

[smoofers]

The check valves are what makes your fuel pump work. If you understand how the fuel pump works on your carbs you will realize that a bad check valve means your carb isn't pumping at its normal flow rate. I've had motors run lean and hot due to a bad check valve.

Replace your check valves and rebuild your carbs.

 

[Tyler Zane]

read pages 6-8, surfjunkie. you will have a much better understanding on how the entire carb works.

http://www.mikuni.com/pdf/sbn_manual.pdf

actually, read the entire thing.

 

[speedysprocket]

12 is not a fuel pump check valve. Not sure how it works or what it does, but my Novis dump extra fuel if I open the throttle then close it fast, and I was told I can stack two or three of those check valves on top of each other to reduce or stop this.

 

[speedysprocket]

Should have read page 8 first...

 

[zwaysfs]

you say that if u take part number 12 and stack 2 or 3 of them it will keep from off throttle bog

 

[zwaysfs]

after reading page 8 a few times it appears that part #12 check valve prevents the low jet from sucking in air when the high jet is not being used. Now so if part 12 is not sealing and the low jet IS sucking air through the high jet do you think its enough to cause a lean condition in 1 cyl and over time cause a small melt down or a run away motor or just make it a pain to try and tune

 

[jetskidude1113]

Depends how bad it is left up. Fuel in your hi low jets section will get drained from you hi speed through the bad check valve out the low speed into the motor by gravity if you let your ski sits for a while between rides, hard starts or dies after takeoff and you will need to choke it or prime to get it to start. When it is running, the negative pressure in the low speed circuit will help keep it close, till it needs to open to hi speed. That’s from what I’ve experienced