not enough power

[Jrock 5877]

got the motor running good in the driveway but when I took it to the river and pushed the throttle forward, we didnt get going very fast. motor sounded alright, wasnt sputtereing or anything, just didnt have much power. I had the throttle all the way forward and the boat wouldnt get out of the hole. Any suggestions?

 

[5150abf]

Re: not enough power

Clean your carbs.

Sounds like your main jets might be dirty.

Pull the float bowl drain plug and they are inside that hole, you will need a really skinny screw driver to get to them, use the widest one you can get through the hole so you don't break an ear off the jet, don't ask how I know that.

Once out take a stranded copper wire and strip it, pull strands off till it will just fit through the jet, run it through a couple times and reassemble.

May solve your problem and certainly can't hurt.

 

[HighTrim]

Re: not enough power

Few things to look at here. If you gave us a MPH at such and such RPM, that would help.

I would personally start by testing the spark and compression, followed by fuel delivery. Let us know if you need help with this.

Short of that, is the boat water logged? Spun hub on the prop? You did remember to unhook the boat from the trailer right when you put her in the water? Dont laugh, it has been done!

 

[Jrock 5877]

Re: not enough power

what is the easiest way to test for compression?

 

[HighTrim]

Re: not enough power

You will need to remove all the plugs, and ground out the plug leads. I like to hook the leads up to my multi spark tester, so that I can ensure adequate spark while testing compression at the same time, but simply grounding them to the block is fine. Some say to bring the outboard to operating temp, and advance the throttle, others say it is unneccessary. It seems to bring on debate, so I will leave that step up to you. Install the compression gauge into the first cylinder, then turn over the motor until the gauge peaks, usually about 7 to 8 cranks. Continue with the remaining cylinders. You should get an even compression within 10 percent on all cylinders, and the spark should jump the gap on the inline tester a good 7/16 of an inch with a bright blue ZAP!!

My guess is that you will find that you are not running on all cylinders, but I guess we will see.

 

[kenmyfam]

Re: not enough power

Just want to ask a few stupid questions.
What size boat do you have and what size motor ???
Is it set up correctly for motor height and trim ???
Is the boat new to you or has it just started doing this ????

 

[Jrock 5877]

Re: not enough power

The boat is a 15 ft tri-hull with a 1977 55hp Johnson 2 cyl . As far as the setup goes, I just put the motor where the holes were on the transom. This is a new boat and motor for me.

 

[tashasdaddy]

Re: not enough power

set up. http://forums.iboats.com/showthread.php?t=269909

 

[Randybeall]

Re: not enough power

Just a thought, if the spark plugs are gapped at .030" like a Champion chart I found says the engine will run great on the muffs but be a dead beat in the lake. Spark plug gap should be .040", made a fool of me for not gettin out the factory manual.

 

[HighTrim]

Re: not enough power

Just a thought, if the spark plugs are gapped at .030" like a Champion chart I found says the engine will run great on the muffs but be a dead beat in the lake. Spark plug gap should be .040", made a fool of me for not gettin out the factory manual.

Im sorry but I will have to humbly disagree with you. 0.030 is the proper gap for the Champion plug. If there is heavy trolling, 0.035 is reccomended. I dont think that has anything to do with his symptoms though.

 

[sstaz]

Re: not enough power

I have a 1970 MFG 15ft trihull that I pulled out of a field. I put a 40hp on the back thinking it was enough. I was wrong, I then went to an 80hp and it solved the problem. The boat is rated for an 85hp, check your hp rating for the boat and I bet you are far short from what it should be.

 

[kenmyfam]

Re: not enough power

I have a 1970 MFG 15ft trihull that I pulled out of a field. I put a 40hp on the back thinking it was enough. I was wrong, I then went to an 80hp and it solved the problem. The boat is rated for an 85hp, check your hp rating for the boat and I bet you are far short from what it should be.

I would expect it to plane out with that outfit if set up correctly.