9.5 sporttwin

[speckle]

Before I through it in the lake I thought I would ask for help.
(1) it is a 1966 9.5 hp
(2) running a 12" jon boat
Problem will not get boat up to speed. Motor starts on first pull. Runs great in barrel. When on the boat it starts off and gets boat up to about 1/2 speed and that is all it will do. It has a miss when it is at this speed.
What I have done.
cleaned carb.; checked coils; cleaned and set points; checked condenser; changed plugs ; checked fuel pump.

 

[jay mendoza]

Re: 9.5 sporttwin

Take a look at the plugs and see if they are running clean. If they are dark, it would point to a rich condition, explaining the missfire, or your ignition may be cutting out, like a bad condensor. Check compression too, maybe you have a head gasket issue.

 

[Huron Angler]

Re: 9.5 sporttwin

Have you run some seafoam thru her mixed with the gas/oil? If you have some buildup anywhere it could be impeding the flow of fuel. Buy a can and burn it thru the motor.

It will produce white smoke if you're doing it right People recommend running it wide open to let that seafoam work it's way thru.

Good luck

 

[kbait]

Re: 9.5 sporttwin

Try running it w/the cowling off. I heard that 9.5's can get an exhaust leak under the powerhead (shift shaft seal/grommet) that can cause that symptom as exhaust displaces oxygen for combustion, causing rich condition.

 

[F_R]

Re: 9.5 sporttwin

Try running it w/the cowling off. I heard that 9.5's can get an exhaust leak under the powerhead (shift shaft seal/grommet) that can cause that symptom as exhaust displaces oxygen for combustion, causing rich condition.

The 9.5s are notorious for the cowling problem, so try that. But realistically, you are probably running on one cylinder. Disconnect and ground one spark plug wire and see how it runs. Then do the same with the other one. Chances are it wont make any difference on one but won't run at all with the other one disconnected---that is the good one.

That will confirm the one-cylinder theory. Your next task is to figure out what is wrong with the bad one. Check compression, and if ok it is back to where you have already been---the ignition system---to see what you missed. Don't forget, it could be as simple as a bad spark plug.

 

[Elbo]

Re: 9.5 sporttwin

While ur in there,check where the plug wire goes into the coil.It could be burned up and the wire be bad.

 

[crxess]

Re: 9.5 sporttwin

The 9.5 has cowl vents. Doubt it is exhaust related since you can run it in the barrel.
Have to agree with possible spark issue. Bad coil or coil wire - dirty/oily or worn points - faulty plug.
Could also be high speed orifice clogged up or partially restricted and not getting enough fuel.

Compression check and look at plugs.
Both the same - probably firing properly.
One fouled - Probably loosing spark
Overly clean (white) - lack of fuel and running to hot.

What is the total weight of the boat - loaded?
Hull configuration and condition?

 

[speckle]

Re: 9.5 sporttwin

Ok guys I took it out yesterday DISASTER!! It started out doing the same thing as before then it reved up and planed the boat for about 50 yards. Then it started missing and slowed to idle with throttle open managed to get to landing . when I tested the coils one tested 6 ohms and the other tested 8.1 ohms can the secondary of coils test good and be bad. I feel like when I cleaned the carb the jets were pluged when I cleaned them I was getting more fuel and the plugs fouled and made the problem worst. The time before both plugs were black. I plan to retest everything on the mag. Thanks for the help. I have ran it with the cover off no differance & ran some SEA FOAM in it . She still starts on first pull.

 

[kbait]

Re: 9.5 sporttwin

Make sure you can get 1/4" bright blue spark on a tester(at various throttle settings) and good compression before you do anything. Poor/marginal spark can manifest itself in many ways..

 

[Rick.]

Re: 9.5 sporttwin

Normally when coils are going they give you trouble as they warm up. For that reason you should test them when the motor is performing poorly and warmed up. You may need to adjust your slow speed needle a bit but it does sound like your ignition is the source of your trouble. Best of luck. Rick.

 

[Elbo]

Re: 9.5 sporttwin

Read the plugs and see whats going on in there.