throttle plates not opening all the way...

[99speedster]

:ack:

Well the title kinda' says it all, I was balancing out the control patterns on the dual throttle levers and noticed that the throttle plates (2 x 720's engines with single carb per engine) do not open up all the way. Even if you adjust the throttle cables so the throttle plate closes for idle , when you open up the throttle controls all the way, the throttle plates will only open 3/4-7/8 of the way!...If you adjust the cable's so the throttle plates open up all the way, then you can not got the plates to close far enough to get the throttle plates back to there idle state (about 1/8-1/4 way open).

It really dont matter how or were you adjust the cable (on the carb or in the middle of the cable by using the adjuster) it wont produce both idle and full throttle conditions--the linkage is not right from the factory.

Is there something I am missing here?..About the only way I would see to change this would be to lengthen the throw of the throttle controls to get more travel or shorten the pivot on the carbs--neither of which are adjustable that I can see on the factory parts.

I have noticed this with other "toys" I have owned and have found ways to correct this, but I'm kinda' new to the boat scene and could use some help if someone has found a fix for this condition....

The boat in question is a very nice factory original 1999 Speedster SK.

thanks for all the help...

This is a simple thing for people to check on "toys" expecially for people looking for more power and speed from a given vehicle...​

 

[kustomkarl]

On most boats even if you got the throttle valve to open completely, you would only get just so many rpms. There is a rev limiter so it won't over rev. Be sure you get idle condition and then adjust it so it gets as much as possible, and let it go. That's all there is...

Karl

 

[pincusa]

It sounds like your idle adjustment screw is set too high. You shouldn't be setting the idle with the cable adjustment.
Back the idle screw all the way out and slacken the cable. Then set your idle with the screw. Make sure you have some slack in the cable and then tighten the cable adjustment screws. That should be able to give you enough travel to get the butterfly to WOT. If they aren't in sync, remove the linkage and get them together.

 

[99speedster]

It sounds like your idle adjustment screw is set too high. You shouldn't be setting the idle with the cable adjustment.
Back the idle screw all the way out and slacken the cable. Then set your idle with the screw. Make sure you have some slack in the cable and then tighten the cable adjustment screws. That should be able to give you enough travel to get the butterfly to WOT. If they aren't in sync, remove the linkage and get them together.

I understand where your going, but base idle is at 1,000 +/- on the water with the littlest amount of slack as possible in the cable to get it to go to WOT--it is on the throttle set screws though...

I have even thought that it was designed this way to compensate for the throttle upon hard turns---but I have not got back into it to observe the throttle up at full throttle..

thanks for the look folks.

Personally I think the throttle cable / handle assembly are a close match, but are not right from the factory. The boat does touch the 48+/- with the speedo as has a couple of other speedsters with twin 720's so I do not believe it's only a problem with "my" boat--I think a bunch of them have this condition....I am not saying the boat should go any faster, just used the example to show that 2 other boats equally equipped perform the same.

I "may" modify the folkrum point in the handle to allow for more cable travel and see how the boat responds.