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Lucyn
New member
Username: lucyn
Post Number: 2
Registered: 09-2009
| | Posted on Thursday, September 03, 2009 - 12:45 pm: | 
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Hoping for some help here.
I have a 2008 BF200 four-stroke that I just purchased along with my 23 ft center console. When I took it out first time, engine rpm's wouldn't exceed 4000. Had my marina (authorized Honda) spend a full day on it, and they have increased RPM's to 5000. In the time they spent, they replaced fuel filter, adjusted throttle and found RPM guage wasn't reading correctly - no engine issues whatsoever. They also said that prop pitch was "probably" one size too large, but didn't think it was enough to have an effect on RPM's.
My understanding is that these engines should pull 5500 -6300 rpm's under load, and my boat should max around 45mph. However, 5000 rpm and 38 mph is all I am getting. Since I head 30-40 miles offshore to fish - the extra speed means something to me.
If this is normal for this engine, that's ok, but my marina can't say. Anyone have any ideas? |
W D Neal
Advanced Member
Username: chawk_man
Post Number: 200
Registered: 09-2008
| | Posted on Thursday, September 03, 2009 - 03:01 pm: |
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WOT should be 6,000 rpm +/- 200. As a general guess, on that boat, your prop should likely be 14 1/4" to 14 1/2" diameter by a 15" (or possibly 17") pitch - no more. A one inch change in pitch will account for around 400 - 500 rpm.
Did the dealer attached the HDS (Honda Diagnistic System) computer and do a complete readout? That should pinpoint the problem right away if it's in the engine itself.
Start with the obvious - is your throttle linkage set up correctly? It is very possible that the throw is set too short at either the controls or at the engine. The shop manual walks you through the correct set up procedure. I believe it's Chapter 3. It's not that simple.
Did the dealer replace the high pressure fuel filter and drain the VST? If not, he should have. It is possible that you have a clogged HP filter. However, typically that will cause a miss at top speed.
Keep us posted on your progress. |
Lucyn
New member
Username: lucyn
Post Number: 3
Registered: 09-2009
| | Posted on Thursday, September 03, 2009 - 03:34 pm: |
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Thanks for the reply. They did attach the HDS and it came back fine. They also replaced the filter and drained the VST. My understanding on prop pitch / diameter is that changing sizes within the approximate range for the boat is simply trading MPH for RPM's, correct?
Seems like the throttle linkage is the place to focus, will let you know what I find.
Thanks |
W D Neal
Advanced Member
Username: chawk_man
Post Number: 201
Registered: 09-2008
| | Posted on Friday, September 04, 2009 - 10:39 am: |
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Agree with going after the throttle linkages - it seems the most likely problem, given your descriptions.
As for prop diameter and pitch tradeoffs - what you want to accomplish is to get the motor running within the WOT range. This properly breaks in the engine and allows you to run at maximum efficiency. On that engine, I believe the max allowable diameter is 15". Honda produces props in 1/4" diameter increments and 1" pitch increments. If you use a prop that keeps you significantly below or significantly above the WOT range, then you will cause excessive wear on the engine and drive train. |
Greg Eastman
Member
Username: grege
Post Number: 6
Registered: 10-2009
| | Posted on Sunday, October 25, 2009 - 12:48 am: |
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Good info. Just bought a BF 200 with a stainless prop and I need to check it out.
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