motor kick back

[sitimortlab]

i finaly got my murcy 25 hp running but has no power checked compression and is 100 on each cyl inder.i noticed that the butterfly never opened so i tryed to manually open it .when i did that i stalled it and tryed to restart .then i started to have severe engin kickback sounds like the motor fires and trys to reverse itselfe .and wont start .it was running fine for several hours just had very littel power.the year is 1986 or 87 model7025226

 

[Chinewalker]

Re: motor kick back

Sounds like you have a timing issue. The timing plate is either too far to engage the carb anymore, or maybe the flywheel key is sheered. Has something been adjusted recently?<br />- Scott

 

[sitimortlab]

Re: motor kick back

thanks for your reply and you were correct the pin was sheered. will that solve the loss of power as well.

 

[Chinewalker]

Re: motor kick back

Yep.... Assuming the advanced timing didn't cook anything inside. <br />- Scott

 

[sitimortlab]

Re: motor kick back

THANKS AGAIN . WHAT DO YOU MEAN BY COOK ANYTHING INSIDE .I KNOW VERY LITTYEL ABOUT MARINE MOTORS. ALSO I JUST BOUGHT IT SO I DONT KNOW IF ANYONE ADJUSTED ANYTHING .WHEN YOU PUSH THE THROTEL FOWARD SHOULD THE BUTTERFLY IN THE CARBRATOR STAY IN A CLOSED POSITION OR OPEN UP AS YOU PUSH FORWARD.

 

[Chinewalker]

Re: motor kick back

Hi Richard,<br /> When you add throttle at the tiller, the linkage should open the butterfly in the carb. Open is fast, closed is slow.<br /> By cooked, I mean the motor could have damage to the pistons if it was run much with the timing advanced. Advanced timing can create pre-ignition and high heat (pinging) conditions which can burn a hole in a piston crown. If the spark plugs are devoid of any carbon and the ceramic portion around the center electrode is white, or even blistered white, then it was run with too much timing. <br /> Now, to address the why of the sheared key. Keys shear for a couple of reasons - either you hit something (or something else in the drivetrain caused a sudden drag on the crankshaft) or the flywheel was removed and never retightened to the proper torque secification. Make sure you sort that out when you fix it...<br />- Scott

 

[sitimortlab]

Re: motor kick back

the spark plugs are encolsed in a way that you cant see the end just a flat metal disk and a pin hole at the end. today i took it out and discovered someone had turned the air adjustment compleatly to the right .at least thats what i think it is for .its on the lower left facing the motor from inside the boat.so i tryed turning it to the left and got better power by twice yet its far from correct .were should the setting be.and i did have the fly wheel off and didnt know about tourking to a special foot lbs .how tight should it be?HOPEFULLY I DIDNT HARM ANYTHING .I NEVER HEARD THE ENGIN PINGING .IT STARTS EASY AND RUNS WELL JUST NO POWER.MY COMPRESSION WAS 110 ON EACH CYLENDER.HOW MIGHT I CHECK IF IM RUNNING ON BOTH CYLENDERS? ALSO IS THERE A EASY WAY FOR ME TO CHECK THE POWERHEAD ?

 

[seldont]

Re: motor kick back

If you get it running good and have good compression which is even on both cylinders take your plugs out and rotate the engine by hand until the piston in each cylinder comes close to top dead center. Take a light and look in the cylinders at each piston and see what you can. If The are still dark looking on top and not gray or white like they have been too hot my opinion is to put your spark plugs back in and run it you are probably okay.

 

[sitimortlab]

Re: motor kick back

I CHECKED THE TOP OF THE PISTONS AND THERE EXCELENT COND. STILL DONT KNOW WHY I HAVE NO POWER

 

[Chinewalker]

Re: motor kick back

Hi Richard,<br /> Are you getting good spark? Does the motor run any differently with one plug wire pulled off and grounded to the motor block? Spark in the open air is not always a good indicator of good spark under compression...<br />- Scott

 

[sitimortlab]

Re: motor kick back

hi again scott. i pulled the top plug and had spark jumping all over even got lit up a bit .then when i more carfully pulled the lower wire i had no spark .i finally feel like im getting somewhere .but where?

 

[sitimortlab]

Re: motor kick back

thanks to all the info i have got it running .only 2 small problems to take care of . i dont know what to torque the fly wheel nut at.and how to set the mimture control.on my 35 hp evenrude i set it 1 and one forth turns would it be the same on the murc