erratic tachometer

C

C-Wolfe

Member
I went out last week and got the right condition to test my WOT, But I don't think my tachometer are workin right. They seem fine at low rpm but starting at around 2800 and over, they start jumping around every now and then mostly going up to the 5000-6000 range, tapping on them seem to reset them for a bit.

With mostly full fuel tank, kicker (6hp-about 60#) extra 6 gal fuel tank, dinghy attach to rooftop (60#) minimum basic gear for overnight camping and fishing, my GPS show a SOG of 27.5 mph. I'm fine with that top speed as I normally cruise at 20-22 mph but would like to know if that is an acceptable top speed. my load was probably much lighter then what I will normally have on board. My RPM was about 3800-4000, unless it was jumping around, that didn't make much sense to me.
I have twin Honda BF50 (2007) ,Honda tach set on #2- 6 poles. Connection on the back look very clean. Is it time to replace them?
This is my first planing hull boat so I have limited experience with testing WOT.
I really appreciate any input. Thanks
 
I had an issue with a jumpy tachometer once and, to make a long story short, the problem was simply a loose battery connection.
 
Journey On has a Honda engine. I had an issue with a jumpy tachometer once and, to make a long story short, the problem was a bad tachometer. Replaced it with a new Honda/Farina unit and all has been well since.

Boris
 
I look at all connection behind the tach and it all look good, did not disconnect, so I might do that and clean them all. If that doesn't solve the problem, I guess it will be time for new gauge. My current one also include the hour meter, is there a way to set new meter to current reading?

Also is my top speed of 27.5 mph acceptable for a light ish load or should I start thinking about prop adjustment? Or just wait until I can get a more reliable rpm reading.
 
C-Wolfe":1j7brzzs said:
I look at all connection behind the tach and it all look good, did not disconnect, so I might do that and clean them all. If that doesn't solve the problem, I guess it will be time for new gauge. My current one also include the hour meter, is there a way to set new meter to current reading?

Also is my top speed of 27.5 mph acceptable for a light ish load or should I start thinking about prop adjustment? Or just wait until I can get a more reliable rpm reading.
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Do you think that 27.5 fast enough for you or not?

FWIW, it is more important what the engine RPM at WOT is than the top speed.
 
Do you think that 27.5 fast enough for you or not?

That is plenty fast, I have no intention to go that fast unless testing my WOT. I max out at around 4000 rpm going at 27.5 mph, It is my first planing hull( had a couple sailboat and a trawler previous to this one) The speed is about what I was expecting but the rpm is much lower then what I thought it should be.

FWIW, it is more important what the engine RPM at WOT is than the top speed.[/quote]

That is what I thought, I'm trying to figure out if my tach need attention or my prop.

Thanks for your input, appreciate it.
 
You should be hitting 5500 to 6000 RPM at WOT with the 50 hp Honda.

The 27.5 mph is a decent number, and I would be happy with it.

Check the engine harness connections--use contact cleaner and burnish with a soft cloth. I like to put a small dab of Corrosion X before putting connectors back together.
 
thataway":74cogpxl said:
You should be hitting 5500 to 6000 RPM at WOT with the 50 hp Honda.

The 27.5 mph is a decent number, and I would be happy with it.

Thanks Bob, that what I wanted to ear before I put much time and money on the problem. I'll focus on the tach.

Check the engine harness connections--use contact cleaner and burnish with a soft cloth. I like to put a small dab of Corrosion X before putting connectors back together.
Will do. Thanks
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