I have an Islandia with the Mercury Optimax 250Hp engine and I'm wondering about the performance. The boat seems sluggish and takes a long time to get up on plane. I checked it today and all plugs are firing. I took some pictures of the plugs and all seemed to be dark black at the tips and last 3 threads see photos. At idle the rpms are at 1000 at 1/2 throttle the rpms are 3500 and the boat goes about 8 MPH. At full throttle the rpms are 5500 and speed is 39 MPH. Time to plane is about 14-15 secs from idle to full throttle. I had a new solas mc-cd-22/39 impeller put in and I JB welded the wear ring which was badly pitted.
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Islandia Mercury M2 Jetdrive 250 HP Opti
- Thread starter Gotrain44
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Dr Honda
Well-Known Member
At first... I was going to say that your top RPM's are low... but with the Solas impeller... I don't know. Do you recall what your peak RPM's were before re-working the pump? (impeller and ring)
When you are checking speed... is that with a GPS or with the speedo in the helm? Also... is that by yourself... or with 12 people on board, and the top up?
It is a big boat... but your number are a little low, and I always felt that it was "Peppy" for it's size. (I have a first gen 240 in mine)
When you are checking speed... is that with a GPS or with the speedo in the helm? Also... is that by yourself... or with 12 people on board, and the top up?
It is a big boat... but your number are a little low, and I always felt that it was "Peppy" for it's size. (I have a first gen 240 in mine)
The rpm's and performance were the same with the stock 4 blade impeller. The solas is supposed to give me better hole shot and better acceleration. The blades on it are more rounded than the stock one. I'm checking speed with a GPS speedometer installed in the dash and I had a gps speedometer app on my phone running that said the same thing.
My son and I were the only two on the boat (350 lbs) and the top was folded and down.
My son and I were the only two on the boat (350 lbs) and the top was folded and down.
Dr Honda
Well-Known Member
LOL.
Yes... we hear that a lot. Originally... the 250 Opti engine was an outboard. So, that expansion chamber wasn't there. But, with the injectors being mounted in the heads... it makes it harder. I can get the plugs out of any of the other Sportjets easy. (90, 120, 175, 210, 240 EFI) But the 200 and 250 opti are rough.
I wouldn't worry too much about the black plug. It's a 2-stroke... so it's still burning oil. But... since your speed and RPM's are down... I would do a compression check. I would also check the air pressure, and fuel pressure. (compression first)
You should be able to upload to youtube. It has a converter. You can even try something like photobucket.
Checked the fuel and air pressure both are within spec. Removed engine cover and belt is tight and is in decent shape. The throttle stop screw is set for wide open so unless the throttle plate wasn't set right or has become decoupled it should be opening all the way. Might just change the filters and be done with it. I may have to live with it till the end of this year and then have a professional do a service on it. :facepalm:
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