Throttle lever

[a4effort]

Scarab 215 , last couple times out as I accelerate my throttle lever starts thumping . I have to back off and re accelerate, sometimes a couple times to make it stop. Feels like a gear not seating when engaged. Anyone know what it is/could be ?? Can I fix it or should I take it in under warranty. I would like to minimize the amount of times other people touch my boat so I would be happy if it's just a matter of disassemble and lubricate.

 

[Mainah]

The active members of this site are predominently yamaha owners and there has been a lot more time to build a knowledge base with those. Hopefully a Scarab owner has seen the same thing and can chime in even if not a regular poster.

That said my first thought as a former seadoo and current yamaha owner is to check your jet pumps. Is there foreign debris? Is it cavatation? Also does this happen on a gradual acceleration or nailing the throttles? Is there any difference?

Good luck!

 

[a4effort]

Maybe @ScarabMike has some input. I don't think it's anything to do with jet. It accelerates fine, no cavitation. It's a mechanism issue I think with the throttle assembly. Seems like something is not seating properly during the forward motion of the lever, some kind of gear maybe and it's causing the throttle assembly to physically move with a thumping in your hand.

 

[Scott E]

Could be the gate is not opening all the way, and catching some of the jet. Check on the trailer for clearance when in forward.

 

[a4effort]

Thank you @Scott E , I will check that first thing tonight.

 

[ScarabMike]

Ok @a4effort , looks like you may have something loose behind the throttle or the reverse grate is out of alignment. In the Rotax powered boats, there are no physical connections to the throttle or engine. The boat is fly-by-wire. This means the issue has to be on the physical connection between the throttle lever, and the reverse bucket. Here is my thought...

Have someone get on the boat with the boat shut off, and you stand on the back of it looking at the reverse bucket. Tell them to push the throttle all the way forward. Make sure the reverse grate completely clears the path of water coming out of the venturi/nozzle. If there it is close or blocking the path, then you will have to adjust the connection. Once thats done, you will be good to go. Also, make sure all the bolts are nice and tight. If you find one that is loose, take it off, and reinstall using loctite (red). Good Luck!

 

[a4effort]

So a big thanks to @ScarabMike and @Scott E . Made my adjustments to the reverse grate and greased up everything nice. The results were great. Not only did the thumping in the throttle lever stop, the overall speed of the boat increased by 3 or 4 mph. The icing on the cake was after about 30 min running the check engine light, which ha been on since 30 hours ( now has 55 hours) is out and did not come back on for the remainder of the day.
Thanks again guys, much appreciated!!