Rough running 45hp honda

[redwoodtom]

Hello, I think that I might have a bad head gasket, although the engine runs pretty good at speed. I've noticed that the engine(1993 45hp honda)idles ok but, when you put it in gear it wants to die and in addition to that there is a large amount of bubbles out the back with the prop wash which increase with rpms. I have two of these on a 21 ft sea cat and the other engine does not produce the bubbles and neither engine appears to overheat and no water in the oil - bad head gasket????? any advice you might have would be greatly appreciated

 

[hondon]

Re: Rough running 45hp honda

There is no exhaust involved with the head gasket that would cause this symptom.<br />.What have you done to troubleshoot?An engine dropping a cylinder due to an ignition or fuel failure is pumping a big bubble of dead cold air right out the exhaust.Fits the profile.A tight exhaust valve that is hanging open to long fits the profile.A cylinder with alot of blow by fits the profile.A deteriorated oilpan gasket fits the profile .Any sign of water intrusion on the plugs?Water in the fuel?What have you done ,maintenance wise too this engine lately?

 

[redwoodtom]

Re: Rough running 45hp honda

Thanks for the reply Hondon, the carbs have just been rebuilt, the oil is 1 year old - engine and lower end. The motors were under water about 1.5 years ago, they were flushed and new plugs installed, all oils changed, electronics changed - ran great and then the motors were mothballed for seven months and I paid a mechanic to do this and then revive them. I was informed that the carbs needed to be rebuilt again, so that was done. The fuel system had no water present and I did not check the plugs - the motor idles at 950 rpms and drops to 500 when put in gear and stalls (the other motor only drops to 750 rpms) again any advice would be greatly appreciated

 

[hondon]

Re: Rough running 45hp honda

There are a menu of things that could cause this chain of events.You first need to do a leakdown test on this engine.That is a much more complete compression test and gives you a good glimpise at the mechanical health of your engine ,plus if that test turns out poor, you can generaly hear where the leakage is occuring.You do'nt elaborate if this thing went down in salt or fresh water. Here is something that most techs miss while rebuilding these carbs.The lift tube can develop tiny invisible cracks ,especially when contaminated with salt water,that unless you are looking for them with an aresol carb cleaner you wo'nt see them.I've only worked in salt so I ca'nt coment on fresh.Also ,950 is book spec ,BUT ,we all know these triples like a little more than that and keep hopeing Honda will revise that spec.Syncing those carbs is a trial in patience and I hope that tech knew not to be too anal about setting those mixture screws exactly even.