195 Open "power"

[aemkay]

Being new to Jetboats I have to ask another question. I have a 2018 195 open with 250 engine. I had it out twice now and last time, I had the feeling sometimes, the boat got more "grip" so to say. It feels like the motor/boat at some point "frees up" (no better idea how to say this) and i easily get 35mph with less than 7k rpm whereas other times, i get 35mph even at close to 8k rpm (which is max of what i ever saw)... is that cavitation or ??

Maybe background: Boat has only about 50h and was sitting outside for about 2 years. But everything works so far...

 

[Sidarousmg]

sounds like cavitation. it feels like driving on snow or slipping a clutch. was there a difference between weight or weight distribution in the boat between the different speeds? if the boat is "loaded", cavitation will be more obvious. you can start by checking under the boat through the intake tunnel, make sure nothing is caught in the grates or wrapped around the shaft. take pictures of the impeller to see what condition it's in. finally, you can easily remove the pump and get a really good look at the impeller/wear ring.

 

[Luc Lafreniere]

What he said. Lol

Also, if you have a faulty spark plug it can cause partial power that cuts in and out. But I agree it sounds more like cavitation.

If you can't spot anything after inspection, it's pretty easy to remove the pump entirely.

Different boat, same engine and pump as Scarab.

 

[aemkay]

Thanks guys!! Have no picture on hand by my impeller looks a bit rusty... I assume thats BAD?

 

[Luc Lafreniere]

Rusty impellers don't usually do anything. I mean, depends on how rusty we're talking about lol. It's the shape that's important, especially leading edges of the impeller. The wear ring (plastic piece) is super important too around the impeller. The spacing tolerance between the impeller and the wear ring needs to be super tight.

Drive shaft needs to be aligned, impeller boot (black rubber thing right before the impeller) needs to be installed correctly and not ripped to shreds. As was mentioned, nothing wrapped around the drive shaft. No rocks, shell, fishing line, twig, etc. anywhere in the pump. The small piece stuck is enough to cause massive problems.

Inspecting it can be a little tricky. You need a flashlight, you need to look at every mm around the impeller, even the hard to see spots.

If you provide pics, they need to be clearly illuminated, not blurry, and showcase all angles of every part of the impeller, drive shaft, intake grate, etc. Because it takes very little to cause cavitation.

It's also a good idea to lift the reverse bucket and inspect inside the jet nozzle with a flashlight again. You should be able to see the impeller from that side as well.

Alternative to all this, do what I posted in the video and pull it out of the boat entirely. That's the ultimate way. But usually you can see the problem without doing that if you follow everything I just recommended.

 

[aemkay]

Allright, so i will "dive into it" and do a thorough inspection. I kinda have the feeling i might just have "wearing parts" replaced for piece of mind. As far as i understand its wear ring and impeller (could you recommend an aftermarket impeller that is an improvement, such as solas and if so, which specifically for our boats? its not a jetski where you get 1000s of infos) and all related o-rings and bearings (shaft if not in good shape). Anything I forgot?

 

[Luc Lafreniere]

The only part that MAY wear is the wear ring. The other parts you only replace if they are damaged. Wear rings are cheap. Impellers are about 4 times the cost of the wear ring.

I would recommend having the pump serviced. They'll pull the pump, remove the nose cone and inspect for water damage to the bearings. Assuming no water is in there, replace the two of rings in there and re-grease or oil (both work). Impeller inspected for damage. Small dings can be filed out. Bigger dings require a new impeller. Wear ring is inspected for deeper scratches or grooves. But typically they are replaced at that point since they are so cheap. The impeller boot is usually fine.

Personally, I don't recommend aftermarket parts unless you're looking for a specific improvement fully understanding you'll be sacrificing something else in the process. The BRP engineers have done their work already to balance all of this. But I can fully understand that some may want a better hole shot because they do lots of waterskiing, or need to compensate for higher elevations, etc. Just appreciate that this means losing something else.

I'm a fan of OEM for this reason.