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Do I need new top end or is this a fuel/carb issue?

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Chips

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My 1997 Speedster has 130 and 140psi on my port engine and it wont rev and it starts right up cold, but after it warms up it is tough to start. When its warm I also have to really work the throttle to get it started, most of the time it fires up when its about 3/4 open.

When I start to plane, the port engine will kick in and rev up. It was worse before, but I adjusted the fuel accelerator pump, it wasn't fully depressing the plunger before. This helped a lot, but it still wont rev when I slam down the throttle in the water.

Also, the boat today would randomly cut out and when I reached for the key to pull it and put it back in, it would beep twice but BEFORE I would pull it off the post.

I also took off the engine bay cover to see if maybe it was overheating, and just started to cruise back to the dock. However, with the engine cover off the engines both seemed to be much crisper, and it was responding better to throttle at speed. I didn't try to stop and gun it with cover off since I just wanted to make it back to my truck...

What do you guys think? Does the port engine sound like its tired and needs a top end?

Thanks!
 
My carbs only have three adjustable screws, one has a plastic tab stopper.

1) Idle stop screw
2) Screw with spring on bow side
3) Screw with plastic tab stopper on stern side of carb.

The other adjustable part is the fuel accelerator part with the plunger. I just set that to be fully depressed when the throttle is all the way open...now I'm thinking that might be flooding it???

What do # 2 & # 3 do?

Thanks!
 
Sorry if these are stupid questions, but if I only have low speed and high speed adjusters, how do I adjust fuel air mixture? Do I have to replace or swap out something internally in the carb?
 
HS is all the way in
LS is 1.25 iirc not more than 1.5 though
count how many turn in to close and compare to numbers above

Not sure if your yr has 787 or 717.

If carbs have not been cleaned I would start taking them apart.
If you have the 787 the raves should be inspected.
 
There are no stupid questions!!! The way I understand it, forgive me I am just learning also, is that the low and high speed screws actually lean out or richen the fuel. So adjusting them changing how much air gets to the gas. Dont take this as gospel though.
 
Thanks guys, and thanks OCOD for the info.

I have the 717's with a single carb on each engine. I don't have the raves.

I cleaned the carb on the bogging engine twice now, and used a Mikuni carb rebuild kit. Although, I am questioning if I actually got the right rebuild kit.

Apparently I have SBN 40i carbs, and the kit I got is for Suber BN38 & BN44. For the record, the engine that I rebuilt the carb on ran exactly as bad before the carb rebuild and both cleanings... The only thing that seemed to help it was adjusting the accelerator pump so that its fully depressed when the throttle is wide open.

THANKS everyone for the help. So far with one bogging engine and the other one cavitating, the boat is still insane fun. My buddy and had had permanent smiles all afternoon just testing the boat out after adjustments. Cant wait until it actually runs right.
 
Well, it was compression... one of the cylinders went out. Hopefully just ring failure - opening things up this afternoon. I shut it down as quickly as possible and limped back to dock on one engine.

The plug on the good cylinder is a perfect medium brown color. The bad one was black...so at least I know the adjustments on the carb were heading in the right direction.

That being said, when I was limping home on the one engine, it would shut off on me. And earlier that day (as well as other days) both engines would cut out. Not much, if any water comes out the pisser when cruising at idle. Anyway, will report back with what the damage is.
 
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