83 V-4 140 horse engine noise

[ditchdigger1]

I'm posting this for a friend. He has a 1983 V-4 140 horse johnson that starts making a noise inside the motor and about half throttle. It started about three months ago when he changed the plugs. They are the correct champion plugs and they show no sign of hitting the pistons. The motor fouls the plugs too often, but otherwise the motor runs fine. I think it may be the needle bearings, but the motor has less than 10 hours on it since it was rebuilt by the dealer. Can anyone tell me what to look for or what to check without taking it apart?

 

[LubeDude]

Re: 83 V-4 140 horse engine noise

Boy, trying to define a "Noise", on the forum is difficult at best. So lets see what we can do, do your best to define the "Noise".

 

[ditchdigger1]

Re: 83 V-4 140 horse engine noise

It sounds to me like a rod is starting to knock. He thinks it might be the carbs. The motor has less than 10 hours since it was rebuilt. They replaced everything but the bearings when they built it.

 

[Solittle]

Re: 83 V-4 140 horse engine noise

Have the shop that did the rebuild check it. The rebuild should have come with a wty.

 

[powerprochris]

Re: 83 V-4 140 horse engine noise

If it is only knocking some at half throttle and not knocking at idle or wot than it might be the plug gap is to close and it is running hot . <br />And i think this could cause plug fouling at idle . The gap is suposed to be .040 <br />Just my 2cent.I could be way off . I would listen to SoLittle .

 

[ditchdigger1]

Re: 83 V-4 140 horse engine noise

How long will this motor run at 1/2 to 3/4 throttle before carbon starts to build up or other things start to go bad? Should this motor be run aroung 5800rpm on a regular basis?