im new to this

[jcb28]

I just bought my first boat today. Is a 1974 monark with a evinrud bigtwin 15' foot fishing boat. Haveing some problems with it. It starts up and idels good it reves up while in nuetreal when I put it in gear still runs good just wont get up to speed even at full throtell can any one help

 

[jbjennings]

Re: im new to this

Howdy,
If you don't mind, post the year and model of your bigtwin.
From what you describe, you have bad or intermittent spark on one cylinder (most likely) or your high speed jet is clogged on the carburetor (not unlikely). You need a $10 spark air gap tester to check for spark, available at most auto parts stores. If your motor is older than say a '70 model, you need to go through the ignition. If it has coils under the flywheel, check for cracks whether you have good spark or not. If they're cracked, you'll soon have spark problems if not already.
JBJ

 

[jcb28]

Re: im new to this

I was told its a 55 hp 74 model guess he lied to me its a 1962 40 hp big twin. So im guessing the coils may be bad. Checked the plugs and the top one is a shine black and the bottom is a dull white thanks for any help

 

[itsaboattime]

Re: im new to this

First Welcome to iboats!!!
There is a wealth of knowledge here and everybody is willing to help.

Follow JBJ's advice and get a spark tester. See what you get on each cylinder. The spark should jump at least 1/4 to 3/8 inch gap.
The best advice I can give you is to get an OMC model specific manual and use it in conjunction with any advice you get from here. That book will pay for itself in no time.
Post the model number so we know exactly what motor we are talking about. Let us know what the results of your spark test are.

 

[retiredfornow]

Re: im new to this

Just a note of encouragement. My first boat came in March, and it didn't run at all. With some serious time on this board, and help from all, it runs like a champ. You're at the right spot. Just follow the suggestions and you'll do fine. These guys are great!

 

[kfa4303]

Re: im new to this

Hi jcb. Welcome to iboats. Here are a couple great links that will help you get her up and running in no time. Use the search funtion here in the forums too, and use "Big Twin" as a search term and you'll also get tons of good stuff. If the motor hasn't been serviced in awhile, you can expect to do some routine maintenance, but you can do virtually all of it yourself. Let us know if you get stuck. Good luck!

http://forums.iboats.com/showthread.php?t=158086
http://www.duckworksmagazine.com/04/s/columns/max/15/index.cfm
http://www.duckworksmagazine.com/07/columns/max/index1.htm
http://www.old-omc.de/
http://forums.iboats.com/showthread.php?t=167352

 

[jcb28]

Re: im new to this

Thanks for the help. The model number is 35933. The spark test came out as top cylinder is no firing I thank it needs coils and maybe a points kit put in. Each cylinder has 100 psi. That's the only thing that's wrong it just not firing on top cylinder. And the carb may need rebuilding. Again thanks for the help

 

[tx1961whaler]

Re: im new to this

Don't feel ripped off. I'd take the 1962 40hp (only if it is a manual shift) over the 1974 50hp any day of the week. I can do without the electramatic, hydroelectric and hydromechanical gearcases if I have a choice.