lost 200 rpm!!!!
 

i heed your help people. i have a 2002 25 baja outlaw with a 496 ho and bravo x drive. i just had the upper rebuilt and i took the boat out and now im only hitting 4600 rpm. before i was hitting 4800. on a calm day with half a tank of gas i could hit 68 gps at 4800. today with same conditons i was only getting 62-63 gps at 4600 rpm. what would be causing this. i checked the prop and the prop is ok. tell me what i should look for and do. thanks guys.

Re: lost 200 rpm!!!!
 

I lost 3-4 mph from a worn gimbal bearing that I picked back up immediately upon replacement. Likely that they checked the gimbal and u-joints when they put the drive back on, but it's a thought.

Re: lost 200 rpm!!!!
 

If the prop, coupler, alignment and drive are ok. The only real thing that can cause a loss of rpm with the same prop is a loss of horsepower. I would check the obvious first, like exhaust system, fuel delivery, plug gaps, might even want to check throttle linkage to make sure with the flame arrestor off you are getting full throttle. Stop lever on throttle body up against stop when throttle lever at helm is fully forward. Just a couple of simple things to check which will affect power and therefore affect top rpm under load.

Ray @ Raylar

Re: lost 200 rpm!!!!
 

I would also check the gear ratio. By changing the gear ratio 1 you will loose 2-300 rpm and who know's what mph, that part depends on the boat.

John S. :D

Re: lost 200 rpm!!!!
 

How about temp and humidity?
Hot humid day you came easily lose 200/300 rpm :( .
Get a nice 65*/70* day with low humidity and you get it back and more sometimes :D

Re: lost 200 rpm!!!!
 

But the strange part is is that he said he just had the upper rebuilt.

Let us know what you find out.

John S. :D

Re: lost 200 rpm!!!!
 

What if the weather is a big factor? My boat slow's down whenthe humidity is heavy and the temp is up. Maybe it has to do with ventilation in the bilge?

Just a thought.
Neal

Re: lost 200 rpm!!!!
 

If gear ratio inadvertently got changed from 1.50 to 1.36 his rpm's would drop 10% . 10% of 5000 would be 500 and that would be if boat was running same exact speed as it was before so even though it's a good suggestion the rpm drop he would have would be double what his complaint is.Add in the speed drop and it would be more like 700 rpm's with the 1.36 ratio.
Did you by chanch go from std bravo gears to straight cut xr gears? Between the preload being tighter on pinion gear and the extra power to turn the xr gears you could see a slight drop in performance,just my guess if applicable,Smitty

Re: lost 200 rpm!!!!
 

I did a swap from XR's to Imco Sc's, ordered 1.5's, went and ran the boat and had an exact 300 rpm difference. Thought I s was loosing a motor, carb trouble or tune up. Wrong. After hours of checking pulled the drive off, wrong ratio. They didn't send me what I ordered. But my rpm was exactly 300 off.

Just going from my experience.

John S. :D

Re: lost 200 rpm!!!!
 

thanks guys. ithe first day i ran it. humidity and heat was very high. but the other day i ran it. about 85 and not very humid it ran the same way.