Engine BOG and power issues

[Rmcrabb]

98 speedster with twin 787s. New engines and freshly rebuilt carbs. Also cleaned and put new bellows on the raves (green bellows)

I have a lack of power at lower RPMs. I have to slowly increase the throttle until the engines reach higher RPMs.

One engine is limited to 4500rpm but one of the carbs is leaking so I'll have to fix that first.

The other engine will reach 7000rpm+ but I have to back up from WOT to do it. It bogs at WOT. Pull the throttle back a little and the boat takes off.

 

[racerxxx]

Are these aftermarket green bellows? If so switch back to your red ones.

Sounds like you have carb issues. Did you clean the accelerator pump lines? There's a restrictor jet in the line, make sure that flows. Did you use genuine mimuni kits in the carbs? Did you use the original springs that were in the carbs? Your really just replace the soft parts in the rebuild.

 

[Rmcrabb]

The stiff green bellows. The spring barely compressed them. But I did save the soft red ones!!!

I used aftermarket rebuild kits (I know I know use the OEM kits)

 

[Rmcrabb]

What kills me is spending $50 per carb when all I need is 1/4 of the parts in the kit. My carbs have external pumps.

And the fuel pumps are new

 

[racerxxx]

Osdparts.com sells parts a la carte. Genuine oem mikuni parts

 

[Rmcrabb]

I'll get the carb leaks fixed.

That dead spot at WOT baffles me. I'm sure it's carb related but as soon as a pulled back on the throttle the engine revs past 7000rpm

 

[Rmcrabb]

Racerxxx I just noticed the fuel filters are between the tank and the fuel pump. In the manual it shows them between the pump and the carbs.

 

[racerxxx]

Between the tank and BEFORE the pumps is where they go. So you're good to go!

 

[Rmcrabb]

That's good! But I see the hose clamps are loose where the fuel line connect to the tank. That's bad

 

[Rmcrabb]

I also just pulled the plugs and it looks like both engines are running a little lean at low speeds. We idled the boat all the way across the lake before we put it on the trailer. Off with the carbs for the 10th time. Wooohooo

 

[racerxxx]

Did you switch any internal springs and levers?

 

[Rmcrabb]

No. I did test the pop off. The all popped at 43-45psi

 

[Rmcrabb]

1.5 turns out on the low speed adjusters

 

[Rmcrabb]

I've ordered OEM kits for my carbs.

I checked my rave valves and the green bellows seem to have soften up quite a bit. I'm going to leave them alone for now and get the carbs up to par.

 

[Rmcrabb]

Just had the boat on the water and WOW! What a difference. The genuine mikuni kits made all the difference in the world.

One of the motors developed a little surge and idled a little rough at the end of our run but maybe I fouled a plug or a rave is stuck.