Scarab Speed Issues

[Ludes600]

i just purchased a 2015 Scarab 195 HO Impulse it currently has 22 hrs total on it the dealership told me it should run 45 mph but but at wot I’m at 35 mph at 8000 rpm does anyone have anysuggestions or is this normal I’m running it with just 2 average sized adults I don’t have a dealer closer than 4 hrs

 

[Scott E]

RPM limit is 8000 so I'd say the issue is with the wear ring and the impeller. Is there any cavitation?

 

[Ludes600]

Yea there is very little when I go from neutral to wot it takes a little bit to catch up to itself the wear ring is good I pulled the impeller the other day because I got stuck in some debris but that isn’t what was causing it because it was doing this before that the dealership told me spark plugs have a big factor in it but I don’t see that the boat only has 21 hrs on it

 

[Scott E]

check the Scarab section, there's a couple of threads. If you have the 195 HO do you have the 250hp engine? The Rotax motors do like newer plugs, but if your at 8000 rpm and only 35 mph, I'd change the ring first, then the impeller. As long as the impeller doesn't mess up the new ring.

 

[Ludes600]

Yea I have the 250 supercharged I the wear ring looked good and the impeller wasn’t bent or anything I guess I’ll try new plugs and see if that helps

 

[Adubbs76]

If you are running at 8,000 RPM it is probably not the plugs it is either some type of drag or weight issue. Or impeller problem.

 

[Ludes600]

What should I look for on the impeller I took it out and it didn’t appear damaged

 

[Scott E]

what's the clearance between the impeller and the wear ring. There's a thread in the scarab section about the 250 hp 195 switching from 159 to 161mm wear ring and impellers mid year. If you have a 161mm ring, and a 159mm impeller, both can look like new and still give you problems.

 

[Ludes600]

I haven’t measured but it’s a tight fit light doesn’t pass thru it around the sides where the blades meet the ring I’m not totally sure what it should look like I don’t know much about this stuff this is my first boat

 

[haknslash]

Is the boat wet slipped?

 

[fireflymedic]

Also just check reverse bucket is not in the jet sream when in forward.

 

[mrmeaniemeateaterman]

Are you at high altitude? Thin air will severely decrease performance.

Bimini Top up? This instantly knocks 5mph off my AR210 top speed.

Just trying to find simplest answers first.

 

[Gym]

Try removing the 12 cases of beer. Seriously though. The wet slip question is one I had. If you are keeping it in the water and have some growth on the hull the drag will be dramatic.

 

[Midnight2V]

If 8000RPM is the engine speed limit, and you are hitting 800RPM, has the boat EVER gone as fast as advertised?