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Check to see if they mounted the engine back in the same mounting hole. They may have used a different mounting hole, which would raise or lower your engine considerably. I think the engine usually is mounted using the 2nd hole from the top, but im not positive. You can measure motor height using the distance from the bottom of the boat to center of the nosecone on the engine. Make sure propshaft is level with the bottom of the boat when measuring. That will give you an exact motor height, and some others on here can give better advice if they knew your exact height. Hope that helps. KentKent Charles 2002 Pantera Classic & 200 Yamaha VMax
What kind of prop were you running (pitch, #blades, etc) vs the new prop? If nothing else changed, I would agree with the above although I cant imagine burying the motor deep enough to drop top speed from 75 to 63, unless you get the cowl itself under water. Typically a buried motor turns lower rpms. You ought to measure the propshaft to pad distance and start around 3″ below or so and work up and down in 1/4″ increments until you find the sweet spot. But I suspect this is a new prop issue rather than a motor height issue…2008 Pantera Classic2014 Mercury Pro XS 200
The old prop was a 25 tempest plus same a new prop. Could I have a motor issues? Something just doesnt seem right. The other prop easily pushed the boat to high sixties /low 70s. I had it in the shop a couple of weeks ago for a water pump replacement the checked the codes and everything checked out good at that time. The engine sounds like it is running fine. It is turning teh prop about 3k right before it planes out. It was very consistent this weekend. Anyway thanks for all of the help.
it might be worth having them check the prop, if they have the appropriate prop blocks available. Had a friend that ran a prop shop for years here and he showed me out-of-the-box props that were 2-3″ off in pitch on one, or even all blades. If they are stacked wrong a sloppy shipper can “splay” the blades and reduce the pitch significantly.2008 Pantera Classic2014 Mercury Pro XS 200
Check to see if youre fuel line is leaking or not flowing freely.
How do I check that?
First thing is to slow down a bit, step back, and ask the question “OK, what was worked on or changed since it last ran reasonably?” Then look at each of those things carefully to make sure a new problem wasnt introduced while fixing an existing problem. New prop can be problematic, hence my advice to make sure every new prop you buy has been put on a prop block to make sure the pitch/rake/cup is as it should be. Two new XXX props out of the box might perform significantly different, but two new XXX props put on prop blocks before use will be almost perfectly identical in performance.. If you dont have any luck there, then start looking for missing horsepower. If the motor is running smoothly, it is always possible that you have an issue in the spark system. My XR6 once was acting like a 115 and it took a couple of us, including a good merc shop to finally figure out that I had a bad coil that worked most of the time, but at WOT would have problems producing a hot enough spark to fire every time. Motor ran smoothly, but was just weak. With that in mind, first thing I would do is replace plugs on your motor. And use what merc recommends, not what Auto-Zone will try to sell you. You want OEM-type replacements to avoid any problems. It is hard to imagine it running smooth if the fuel system is broken. It will run lean and not run very well. Id save fuel-related issues as a last-resort unless something (say the primer bulb) was replaced and possibly put in backward. Non-merc primer bulbs have been known to cause lots of fuel-related issues, from leaking check-valves to stuck check-vavles to restrictions. One other thing to check is to remove the cowl and make sure every bolt and screw and nut is tight. The switchboxes use the bolts that hold them to the block as a ground. Loose bolts provide a poor ground which can cause issues up to and including melting a piston because the timing can get way out of whack. Id bet on either plugs, or something that was changed during the repairs… dropping from 75 to 63 is a _huge_ drop and it is hard to imagine a prop that far out of whack. And motor height is not going to make that big a difference unless the motor is so low it would look obviously wrong. BTW, thats a good motor, but the 2.5s are not known for torque unless you go the racing division route of much higher compression. Which means that any little glitch can prevent it from getting up to its peak horsepower RPM which is well over 5,000 RPM.Last edited by oldtimer57 on July 22nd, 2008, 7:23 pm, edited 1 time in total.2008 Pantera Classic2014 Mercury Pro XS 200
Thanks old timer. My old prop is currently being repairs. They are putting it on a block and fixing it. i will take the new prop there as well. I did run a rebuilt tempest 25 with the same result as the new prop. I changed the plugs to NGK plugs which is what the merc mechanic reccommended. I hopefully will get to run the rebuilt prop and see whats going on there. Like I said it is turning 5700 rpms it is just much slower than normal. The motor looks to be about the same height is was before. It has never been a fast boat out of the hole but is would run with most of them on top end. Right now it just really feels slow. It was running a little rough sunday but the was first thing in the am after that is sounded as good as usual. Anyhow i appreiciate the help. I will start working on it and report back the results. Any other help is always recommended.
OK, things are maybe a bit simpler. Some math… I am assuming you are running a 1.75:1 gear ratio lower unit, which is typical for 200hp mercs. Theoretical top speed with a 25″ prop is speed = 5700 / 1.75 * 25 * 60 / 12 / 5280 => 78 mph at 0% slip You are running 63, so slip = 15mph = 19%+. So your slip is roughly double what is reasonable. The most likely candidate to cause that is that the motor is _way_ too high, wetting so little blade area that it is slipping badly. Also this will likely kill hole-shot as the prop should ventilate at that height like crazy letting the motor wind way on up in the RPM band. If the prop really is a 25″ pitch, and there is nothing wrong with it in terms of blade area (prop shops can reduce blade area, and also can thin the blades enough that they flex under load and lose pitch) then this has to be a height issue unless you have some serious issue in front of the prop. For example, a gash on the pad that is disrupting the water flow off the pad and onto the gearcase/prop. Or a (somehow) damaged gearcase that is disrupting water flow into the prop blades. Ive even seen the old-style speedo pitot that mounts on the transom cause this mounted directly in front of the gearcase, as can a transducer puck mounted there. Assuming nothing was added in that area, check the height. They might have changed holes on you and raised it up higher than normal.2008 Pantera Classic2014 Mercury Pro XS 200
Short answer yes.However from what I hear Furys like to be a little deeper and it sounds like you have more slip, so start dropping the engine 1/4″ at a time and see if you get any improvements.Irv
I run a 24 Fury at 2500 ft on my PIV/200HO and run 67-68 with just me and 43 gallons and all my tackle. At sea level the same setup will run 70, I bet youre going to like the Fury at sea level. Mine was worked by Mark Croxton, I bet he can get you a couple miles per hour out of yours as well.
I thought that would be the case, but I still wanted to ask. Thanks all. Unfortunately I will be in San Diego County shortly and any advancement in speed I get will be a moot point with speed limits at 35mph. Looks like my next trip to Havasu will have to be soon. Love the Fury by the way. My hole shot is amazing and it just feels better on the water. Dont know enough to be able to elaborate but I like it.Last edited by SuicideNemesis on March 28th, 2012, 9:22 pm, edited 1 time in total.- Chaz
Lower it and youll like it even more. Very responsive and fun to drive.
Usually in the 40s though that engine is not a high powerhouse.
I just replaced the powerhead in my 04 Merc 90 2 stroke. I am in the break-in period now, but I have been trying to find out how fast my boat should be with that motor. I have a 95 Margay II. Any information is helpful. Right now Im getting about 35 mph, 4900rpm at WOT.
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