Force 125 Rebuild - Behavior and Miss

jimdi · Sep 17, 2001

I just had my Force 125 rebuilt - new pistons - rings - etc. (It had broken a piston ring) The oil mix for break in is about 1.5 times normal - and the timing is retarded - 2@. I drove it for the first time yesterday for about 4 hours- and it has a more vibration than normal - and it has developed a MISS - it kicks - about the time that the trottle plates start to open. The idle mixture seems right. - Halfway between rich roll off an lean. Any ideas what would cause this? It smoothes out at higher RPM - but the mid-ranges all seem rough.

sony2001 · Sep 17, 2001

Re: Force 125 Rebuild - Behavior and Miss

Sounds as if one carb is not carrying two cylinders at idle. What are your new mixture screws settings?

jimdi · Sep 17, 2001

Re: Force 125 Rebuild - Behavior and Miss

It idles OK - the mixture screws are at 3/4 out - just where they were in the days before the rebuild. The problem arises when the throttle plates open - jim

sony2001 · Sep 17, 2001

Re: Force 125 Rebuild - Behavior and Miss

The arrow on the cam is level to the middle of the roller at idle? If you unscrew the idle SPEED screw the rpm's will drop by 100 or so? Where is the arrow re the cam at this setting?

jimdi · Sep 18, 2001

Re: Force 125 Rebuild - Behavior and Miss

Yes the linkage is set exactly as per the Force Book. WOT likage is corect - idle is correct. the marks line up with the roller cam. This boat ran beautifully before the rebuild - now it shutters - and has a miss in the middle speeds. I am taking it back to the mechanic who rebuilt it. Also one other note - when it was rebuilt - all 4 pistons were replaced. 3 cyls honed and 1 bored. Mechanic claimed book calls for only cyl that need to bored should be - I thought this would unbalance the engine - he claims pistons are balanced. What are the rules for boring???????

Rex · Sep 18, 2001

Re: Force 125 Rebuild - Behavior and Miss

FOR INLINE BORING THE CLEARANCE SHOULD BE ABOUT .010 SINCE YOU ARE RUNNING MORE OIL OPEN UP YOUR LOW SPEED JETS THEN SET THE RPM UP. ?DOES SHE IDLE OK. IT SOUND TO ME THAT IT IS IN THE ELECTRIC SYSTEM. I WOULD SET THE TIMING BACK TO WHERE IT SHOULD BE NOW THIS IS JUST A GUESS. REX

jimdi · Sep 19, 2001

Re: Force 125 Rebuild - Behavior and Miss

I did turn the idle up - it's acceptable. But mid range speeds kick and miss - and cause vibration. It does smooth out at higher speeds (I have yet to open it all the way up during break in) ignition (by everything I have read - should be set down 2 degrees for break-in. the ignition system worked fine prior to rebuild. HAS ANYONE HEARD - IS IT OK TO HONE 3 CYLS AND ONLY BORE ONE???? Doesn't this cause a balance problem - or doesn't it matter on outboards????

Backlash · Sep 19, 2001

Re: Force 125 Rebuild - Behavior and Miss

Hey Jim, You're OK to only replace one piston. It won't put your engine out of balance. How much longer to go on the break-in. Possible the problem will go away when you get back to your regular mix of fuel/oil. It sure sounds like a carburation problem to me. Backlash

jimdi · Sep 19, 2001

Re: Force 125 Rebuild - Behavior and Miss

I replaced ALL 4 pistons - it's just that we HONED 3 cyls and BORED 1 - I ASSUMED that meant 1 oversize piston and 3 normal new pistons - AM I WRONG IN THAT ASSUMPTION? I now have 4 hours on the engine - I have heard 2 tanksfulls (36 gal each on mine) to 10 hours for break - in - what is the correct time for break - in?? My mechanic called me back and said I had a leaking exhaust tube riching up the air under the cowl - he replaced that - but I told him I wanted in ran in water at the intermitent speed where I had problems before I take it back. SO BACK TO THE QUESTION - WHEN THEY BORE A PISTON - ISN'T THE PISTON OVERSIZED? AND WOULDN'T THAT THROW THE ENGINE OUT OF BALANCE??? Or is that a common practice on outboards????

Backlash · Sep 19, 2001

Re: Force 125 Rebuild - Behavior and Miss

Yes the piston will be oversize. No it won't put it out of balance.

Backlash

Rex · Sep 19, 2001

Re: Force 125 Rebuild - Behavior and Miss

Yes it well be a little bigger but not that much. check on the carbs. and the spark to each plug i do not think that it. I would say carbs. good luck Rex Rexa1925@iwon.com

jimdi · Sep 20, 2001

Re: Force 125 Rebuild - Behavior and Miss

Thanks everyone - I was concerned that the oversized piston would cause my boat to vibrate forever- Atleast if it's a carb adjustment - or a timing adjustment - it's a solveable problem.

manowar · Sep 22, 2001

Re: Force 125 Rebuild - Behavior and Miss

are you sure all air lines to motor and carbs are correct if not would decrease power while trying to run top end check all electric connections also stator might not be operating right

Force 125 Rebuild - Behavior and Miss

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