1981 35hp johnson how fast should it go?

[j5ffx]

Hi, i have a 1981 35hp johnson 10x13 prop on a 14ft glassfiber boat with cuddy, 2 people on board plus all the electronics., swivel seats, safety equipment etc. A tacho is now fitted and the pulse wire is connected one of the yellow wires and set to 5P.

ok, i got the boat last year (my first) and it got up on the plane and did 17knots at wot. i tuck it out again and the engine had lost revs and power and wouldnt plane and i was lucky to get 8knots out of it!!! checked compression that was ok, replaced some electrics, plugs, carb kit, set the link and sink, fitted tacho and now at wot it get up on the plane and at wot does 20knots. ok i think thats fine (i dont know any differant) BUT the tacho reads 2800 revs!!!!! and ticks over at 850 revs ok much less than this and it starts to stall out. So could someone tell me if it really is only doing 2800 revs and theres a lot more power to pull out of that engine or is it basically going flat out and the new teleflex tacho is set wrong or faulty? how fast should it go?
thanks in advance for any help.

 

[Barnacle_Bill]

Re: 1981 35hp johnson how fast should it go?

5P is the correct setting for that motor. Check your charging circuit. A defective rectifier or stator can cause bad tach readings.

 

[tashasdaddy]

Re: 1981 35hp johnson how fast should it go?

i agree, read the installation instruction, and it sounds like installation is right.

 

[TerryMSU]

Re: 1981 35hp johnson how fast should it go?

I have a 35HP Johnson (made in 1978). I have it on a rather overly heavy (Wet foam?) 14ft fiberglass tri-hull. With just me and my stuff in the boat, my 10X10.5 prop will let me run at 27MPH (measured by the GPS). I am a pretty small guy (about 135lbs), but I have a 25Lb anchor, an electric trolling motor with a foot pedal control and a large 12 trolling battery. Again, the boat appears to be quite heavy but your spped is a little slow given my results. I wonder if your prop is wrong. Does anyone have a recomendation for a prop for his setup (or mine)?

I do not have a tach on my boat so I cannot tell how fast the motor is turning. One other thought... My motor tries to not run as fast as I would like at first. It is if it is running on only one cylinder. If I run it in neutral at the highest RPM I can make without cheating the neutral lockout, it will emit white smoke thru the underwater exaust for a couple of minutes. It settles down after a couple of minutes and then runs real nice.

 

[tashasdaddy]

Re: 1981 35hp johnson how fast should it go?

Terry sound like you are in for a carb cleaning and rebuild.

 

[freddyray21]

Re: 1981 35hp johnson how fast should it go?

that would be 23 mph. IMO that is pretty good for the boat you describe. I would think the tach is off due to one of the reasons already mentioned.

 

[j5ffx]

Re: 1981 35hp johnson how fast should it go?

cheers everyone, i have already changed the rectifier but i havent looked/checked the stator! in fact ive only just found out what it is!!! lol
i guess this is how we learn. by the way im also carrying a anchor plus a 4hp backup engine and 2 batteries! the boat is a bonwitco 400 ski/fishing boat. it seems to me from everything ive read that the tacho is giving a false reading which could be the stator as mentioned by bhile, cheers mate.
i surpose the best thing to do now is get the tacho working correctly and then i can if needed play around with differant props.
thanks again to everyone.