Ongoing speedster issue

[Gary pope]

I have been dealing with this issue on and off all summer long. I replaced the starboard motor with a remanufactured one from SBT. It runs fine. The port motor I can't seem to get above maybe 3500 RPMs and then bogs down. I rebuild all for carburetors on the boat with official Mikuni kits and I was continuing to have the same issues, so I took it to Dee's marine down in Sterling Heights Michigan, they replace the spark plug wire boots and I guess a few O rings in the carburetor they said that it had a Yamaha o ring instead of a Sea-Doo o ring... after I paid them the $400 and they told me it should be good to go, the thing is still bogging down does anybody have any suggestions? It smells like it's running real real rich

 

[jknightg]

What year ?
My 98 twin 787 is fitted with the speed pumps on the carbs which help it shift from the low speed jet
If faulty it struggles to get above 3500

 

[Gary pope]

It's a 95 with twin 656x motors. One is new from sbt, it runs fine. The other one is not but I rebuilt all 4 carbs with mikuni kits and replaced all needle & seats.

 

[HMH]

I do not know much about them. I have one that is acting similar. If I pull and release the choke it will take off. I have read where the choke will actually hang up and give a similar problem.

 

[jknightg]

Do the carbs have a speed pump?
One per engine
They are at the flywheel end

 

[Gary pope]

They do have a fuel pump mounted right on the carbs. They start fine just seem like they bog down after half throttle.

 

[Gary pope]

Hmm.... I'll have to try that next time I take her out this weekend..(pulling on the choke)

 

[jknightg]

Looking at the parts catalogue, it looks like you're carburettors aren't fitted with a speed pump
It's when the carb switches from low-speed to the high-speed jets, there is a tuning issue I would suggest. Sorry I don't know enough about your carbs to be specific.

 

[Gary pope]

Well I do know from when I rebuild these carburetors that they do you have low speed and high-speed Jets. I did adjust them per the manual high speed is all the way in low-speed is out I believe one and a quarter turn

 

[HMH]

Just wondering if you tried the choke and if it worked for you.

 

[Gary pope]

I did try it while on the trailer but it didn't get any better. It actually bogged down more. I am actually at my wits end with this and nobody seems to figure out what's going on with it so I'll probably just sell the damn thing, even though it's got a brand new motor in her

 

[2x2smoke]

Swap the carbs between the two engines to see if its a problem in those carbs or not

if so, take them apart again and triple check your work or try to adjust and tune them on the water

if not look at the fuel supply system, engine compression, electronic components on the old engine. swap those back and forth as well if you need to if a diagnosis isnt obvious.