Freestyle Where did my power go…

650sxtryhard

650sxtryhard

Location
New Zealand
Superjet based dasa 850 with mikuni 46s
Pre lock down was running mint all the power. 4 weeks later take it out to the surf and no bottom end. Go full throttle wait 3 seconds, it builds up then goes nuts pump can’t hold it. Or hold it wide pump gets a touch of air and full power can’t hold on. Pissers going as strong as ever
Checked b pipe screws all clear trying to avoid pulling carbs off
Any help appreciated
 
Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
JC-SuperJet said:
First, since the Weather in New Zealand is cooler than a Month ago, try opening (Richen) the Low Speed Adjustment Screws by a 1/4 turn. See if that leads to a better response.

Your Carbs could just be too Lean for the current Air Density.

If not, clean and inspect the Power Valves. If that doesn't help, then:

Inspect and Clean the Carbs and Rebuild as necessary. Look for Gum/Varnish build-up, dirty Internal Filters and tired stretched-out Regulator Diaphragms.

And if you pull the Carbs, might as well inspect the Reeds.
Click to expand...
Weather in New Zealand should be getting warmer, they have opposite seasons!!!!! Its spring time there!!!!!!!!!
 
Hirschfelt

Hirschfelt

Location
Buffalo, NY
B pipe screws are clear meaning they turn and you confirmed the hole is open and no debris? Clogged tuning holes act very similar to what you are describing.
 
Rushford_Ripper

Rushford_Ripper

Site Supporter
Location
New York
What kind of electronics? Check to see if your flywheel/stator plate/woodruff key are in spec. Did you put in new plugs? Check plug wires? Sounds like something is loose somewhere connection wise possibly.
 
650sxtryhard

650sxtryhard

Location
New Zealand
So carbs cleaned, new plugs just testing on the trailer still not right. one pull revs up crisp next time sounds like it’s stumbling along
 

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ngerk

ngerk

Location
Argo, Al
So a buddy had, what sounds like, a similar experience. Superjet would bog really bad for several seconds then unexpectedly take off. If you hopped out the water it would immediately take off. He didn’t try too hard to fix it and ended up going to a Phantom with a different engine and carb set up and the problem was still there. I put together a Zeeltronic set up and it solved it. So, for him, it was something in the electronics without a doubt.
 
M

mikesx

My 61x MSD boat had been running perfect and started acting like a rich bog. That should’ve been my first clue, anyway I rejetted, got it crispy again and a weekend later my ign coil goes. After replacing coil, had to go back to original jets. I had tuned around what all along was an expiring ign coil.
 
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Quinc

Quinc

Buy a Superjet
Location
California
Did you check your pop off when you had the carbs apart? Could be the needle is sticking. Also do a leak down test. Test your engine water jacket too.
 
aboarder

aboarder

Location
Goodwood, ON
I repaired one using a product like JB Weld. I can't remember what it was called, but I did some research and found others suggesting it. It was at my hardware store, so not an uncommon product. I had a very light coat of grease on the flywheel key, put it in the slot and filled the area around the key. When the resin was set, I pulled the key and used a file to shape the area.

It's been over a year and it's still holding, but mine wasn't quite as bad as yours.
 
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