99 speedster 4500rpm stumble

[robomatic12]

Got twin 787's in my 99 speedster. When I try to accelerate the revs will hang up at 4500 and stumble, if I pull the chokes out while this is happening they will die out completely (Don't think it needs more fuel). If I back off the throttle and come back on it, it will rev up happily to full throttle around 7k rpm. Boat runs great once up in the higher rev range.

What I have done:

Installed new Fram G2 fuel filters
Cleaned out carbs and rebuild with aftermarket kit (Winderosa)
Checked pop-off value, it is set to 30psi on all 4 carbs
New carb base gaskets
Compression is 150psi in all cylinders
New spark plugs BR8ES gapped properly

Where can I find an oem carb rebuild kit+needle/seat? Should I rebuild the accelerator pumps? Should I try to find a new diaphram for the external fuel pumps?

Thank you

 

[Dr Honda]

The external pumps almost never go bad. So... I wouldn't mess with them. Other that to make sure they are clean.

The Windrosa carb diaphragms suck. They normally cause hard re-starts... but I'm assuming the problem was there before the rebuild?


If you slowly build RPM's... will it still do it? Or does it only do it when you hit the throttles fast?

 

[robomatic12]

Should I take the external pumps apart to clean them?

Actually I rebuilt the carbs when I bought the boat but had previously been out with the previous owner and the problem was not apparent at all. So perhaps the cheap kit is the problem? Should I throw new jets and seats in anyways?

Slowly building rpm does not effect it nearly as much as a sudden full throttle stab. The sudden wot is when the issue is the worst.

 

[robomatic12]

I'm going to order a oem rebuild kit with oem needles/seats. What should I set the pop-off to? I see that the factory pop-off should be from 36 - 40psi. The boat had 30psi springs in it originally. What does this mean?

Also another side question, I got water in my front storage compartment. It never seems to drain out or there is no drain hole that I can find. Should I just soak it up with towels?