Post rebuild tuning?, Force 85hp.

[Mi-boy]

I recently rebuilt a 1988 force 85hp outboard, 30 over, all new pistions and bearings. I set the advance at 28 degrees, with throttles wide open at slow cranking speed. I set the carb tuning screws at 1 1/2 turns out. I did not rebuild the carbs or fuel pump. I put the muffs on it this morning and it fired after just a few seconds and purred like a kitten, I only idled it a few minutes on the muffs then took it too the lake. backed it in the water, fired it up all seemed good so I took it out. only ran it 15 or twenty minutes. it seemed a little boggy and jumpy. when slowly opening the throttle it seems it hesitate for a while then zoom it really takes off, then it sort of bogs again. it definitely has plenty of power when it jumps up. Just wondering if anyone has any trouble shooting advice. also I was getting good water through the exhaust, I did put a new water pump in it. after running it the head was fairly warm but not hot enough to burn or cause pain. One other thing, on the inside of the flywheel the is a sort of magnetic I believe strip that ride on the outside of he stator assembly. this is not fixed on my flywheel and can be jiggled around, is this supposed to be like that. thanks in advance! PS I ran 25 to 1 fuel oil.

 

[Mi-boy]

Sorry double posted, please reply on other topic of the same name. Moderators please delete this topic, I don't know how.

 

[pnwboat]

That "strip" you described is a magnet that is supposed to be securely epoxied to the inner circumference of the flywheel. It is part of the ignition system. It generates the voltage used by the CD Modules to fire the spark plugs. You should remove the flywheel and remove the magnet, clean off any rust and corrosion from the area of the flywheel where the magnetic strip sits and epoxy it back on. Use a wire wheel or something similat to remove the rust. J B Weld, PC-7 or Hi temp. Devcon are a few epoxies that you can use and are usually available at most hardware stores.

 

[Jiggz]

After re-attaching the magnet, before going on any further. With new pistons, you need to do a break in using 25:1 fuel mix. There are certain speeds and period required to properly break her in. Another is if you have a new head gasket, you also need to re-torque it after the first run. If you have not done so, install a clear fuel filter between the fuel pump outlet and the carbs' inlet. This is tremendously help with future troubleshooting while at the same time providing a secondary filter. Even a Fram G-2 that costs less than $5 will suffice.

 

[Mi-boy]

Thanks for the replies, I intended to install another filter, I will do that. I kind of suspected that was the case with the flywheel. Could that be causing my issues if that magnet is slipping and not turning at full RPMS? I intended to do the proper break in procedure, and re torque the head, however I didn't like the way the engine was running so I stopped after just 15 minutes, to seek advice.

 

[Jiggz]

After you fix the magnet, do a test run again. Even at idle you should be able to tell if the motor is running correctly or not. You can at least fast idle it in a water tank and see if it will hit 1800~2000 RPM with smooth running. If not report the status of the clear fuel filter and if there is constant spark on all cylinders.

 

[Mi-boy]

Thanks for the speedy replies, I will take care of the magnet and add a clear fuel filter, I didn't do a full blown link and sync, however I did look pretty closely at all three butterflies when I put it all together. Im thinking it may be nothing more then the magnet and carb tuning, it runs awesome at idle, if anything id like to idle it down a bit. I don't have a tach on it right now but it seem high, clunks fairly hard going into gear, and goes pretty fast at idle. in any event I will do as suggested and move from there. I work all weekend now so probably will not update until Monday at the earliest. thanks again.

 

[jerryjerry05]

At 30 over you might want to keep an eye on the condition of the burn.
The jets might need to be opened a bit or go to the next size up.
Run it like you stole it!
If it's gonna break do it now.
I

 

[Mi-boy]

What do you mean by condition of the burn? I'm not familiar with that terminology. Honestly jetting hadn't crossed my mind at all, I figured the 30 over wasn't all significant enough to worry about on those large diameter pistons.

 

[jerryjerry05]

The plugs will burn a lighter/ hotter color.
In 72 I was rebuilding a Triumph Motorcycle.
Bored it out and neglected to re-jet (very new to anything mechanical) It ran for about 30min and melted a hole in one of the pistons.
Here's the part # for the next one.FO13191 that's a .076
Keep an eye on the motor as you run it.
Run it at 4000 for a 5 minutes and then turn the key off.
Then pull the plugs and check the condition of the burn.
It needs to be shut off and not slowed down.

 

[Mi-boy]

Ok guys, working on the motor again today, added the fuel filter and pulled the flywheel. I did the link and sync on the carbs again, after pulling the front baffle off the carbs. where I currently have it set in neutral the butterflies are just a sliver open from fully closed, at wide open they are maybe 10 or 15 degrees shy of fully open. Its almost like my throttle cable should have a little more throw in it. What do you guys think? Also I discovered something I hadn't previously noticed, after installing the fuel filter I pumped up the bulb hard, and gas sprayed out the external air jet, and a port at the top of the left side, on the center carb. did it a few times and this only occurred on the center carb. Seems to me that indicated something wrong with it. FWIW I rebuilt the engine because the center piston was blown. What would cause that carb to do that. I foresee a carb rebuild in the near future.

 

[Mi-boy]

Well assumed the carb issue was a float needle problem. took it apart and there was a chunk of rubber in the needle seat. clean it up and reassembled, improved but not fixed. took it apart again needle and seat look good, so I tweak the tab the need rides on up a bit. put it all back together. now I can get fuel to **** out both holes on center and top carb. I have to squeeze pretty hard on the bulb though. and it defintetely doesn't shoot out like before. the bulb still seems to hold pressure afterwards as well. So I'm tempted to try running it tomorrow and pay close attention for any leaks while its running. I have replaced all fuel line now. I also took note of the high speed jet size, and it is .074. Do you think im safe to try running it and .030 over, or should I jet up to .076 before running it. If it helps any im at about 1250 ft above sea level.

 

[Jiggz]

This is with the presumption that timing has already been set correctly. With the control lever in full forward position (WOT), the throttles (on all carbs) should be at horizontal (in reference to the carb body or throat), no more no less. If they are less than horizontal then you should adjust the control tower-throttle link (a short threaded rod with swivels on both ends) by unscrewing the swivel to lengthen it or vice versa. Just make sure you re-tighten the locking nut.

After this adjustment with the control lever in neutral, the throttles should be fully closed or if the idle screw is already set, the throttles should be slightly open. If you are doing the synch, you will be better off backing off the idle screw (located at the bottom of the timing/control tower). In this way, you can tell throttles are fully closed. If they are slightly opened, you can adjust the link rod again but you do not need to. The reason why is because when you set you idle screw the throttles will open up a bit anyways. After you set your motor to run and need to adjust the idle, do so with the idle screw adjustment located at the bottom of the timing/control tower. At the driveway on muffs in neutral it should be around 900~1000 RPM. In water, in gear idle should be around 750~850.

As for the fuel squirting out of the vent hole on the side, it is an indication carb float is not properly set or the needle valve is worn out and not sealing shut the inlet port. It does not require a full carb rebuild instead remove the bowl, get some carb cleaner and shoot clean the needle and the inlet port. Check the float make sure it is not punch out or has a hole in it. If it does, replace it. Check the setting to make sure it closes the inlet port when in horizontal. There is tab adjustment to make this adjustment which is where the needle valve seats. Before re-installing check the operation by connecting a short fuel hose to the fuel inlet nipple and simulate fuel by blowing into it. With the float lowered, you should be able to blow through. With the other hand, slowly raise the float and as soon as it reaches horizontal you should feel resistance and unable to blow into the hose.

Note, when working or carbs, make sure you put a rag or something to catch any screw that might fall into the lower cowling. This is especially true with the bowl brass screw which is very hard to find.

 

[Mi-boy]

So if the needles appear to be in good condition, and the seat is clean, and the float is in good condition and nothing inside it. and I still can push fuel through with the bulb, what should I do. I did notice before adjusting the tab on the middle carb the float had to travel well past horizontal to seat the needle, after adjusting the tab it stops at horizontal. I still can push some fuel through if I squeeze hard enough. as for the butterflies, with timing set, and idler screw backed off. I cannot achieve full closed, to full open on the butterflies. my cable ends simply don't travel far enough to cycle the lobe that opens the butterflies. I either can be fully closed to not fully. or fully open to not fully closed. or somewhere in between. I can find no other limiting factor then the travel of the throttle cable.

 

[Mi-boy]

I have noticed that my throttle lever itself seems to have more travel then the cable allows. perhaps its not the correct cable.

 

[Jiggz]

Well if you squeeze really hard, yes the fuel will go through since the needle valve can only stop so many pressure of fuel going into the inlet port. The needle valve function is not absolute that it will stop any fuel coming in regardless of pressure. However, it should stop fuel from coming in when only the pressure from the fuel pump is applied. And that is exactly the key, with the engine running, the carb should not have fuel overflow from the vent hole on the side. If it does, then the needle valve or the float is not set properly.

 

[Mi-boy]

Brought the boat to the lake, idled at dock for 15 minutes, hiccupped a few times at low idle but ran well idle up a bit. took her out brought it slowly on to plane running awesome for a couple minutes, then bogs and dies out wouldn't start after that. pulled the plugs while trying to start cleaned them, replaced try again and pulled them out again. top two seemed aweful dry. and now I can get gas to come out of bottom carb when squeezing the bulb. Got home placed thumb over each spark plug hole, definite compression on all three. I will get the tester and check all three. then placed a plug in all three boots, definite spark on all three. What it the proper way to determine proper spark. I'm thinking right now my best bet is too order a rebuild kit for all three carbs. PS the clear filter filled up full via the fuel pump and was full when the motor died. So it seems my fuel pump is working properly. I'm wondering if the float needle on the bottom carb stopped seating and starved the carbs above it of fuel. Its like I'm so close just gotta figure out the last little detail.

 

[Frank Acampora]

Before you run it again, watch my video at the top of the page: Tutorial. Second--If the engine was rebuilt because of a detonated center piston, automatically assume that the carb was at fault, delivering a lean run. Remove all three carbs and go over them with a fine tooth comb. Better to take extra time now than to rebuild again. Then, go over the complete fuel system from tank to carbs looking for crap or partial clogs. Certainly add a cheap paper filter between the fuel pump and carbs.

 

[Jiggz]

Brought the boat to the lake, idled at dock for 15 minutes, hiccupped a few times at low idle but ran well idle up a bit. took her out brought it slowly on to plane running awesome for a couple minutes, then bogs and dies out wouldn't start after that. pulled the plugs while trying to start cleaned them, replaced try again and pulled them out again. top two seemed aweful dry. and now I can get gas to come out of bottom carb when squeezing the bulb. Got home placed thumb over each spark plug hole, definite compression on all three. I will get the tester and check all three. then placed a plug in all three boots, definite spark on all three. What it the proper way to determine proper spark. I'm thinking right now my best bet is too order a rebuild kit for all three carbs. PS the clear filter filled up full via the fuel pump and was full when the motor died. So it seems my fuel pump is working properly. I'm wondering if the float needle on the bottom carb stopped seating and starved the carbs above it of fuel. Its like I'm so close just gotta figure out the last little detail.

With the clear fuel filter staying full at least you can localize your problem to carb float settings. As for the top two plugs being dry, it is an indication fuel-oil mix is not getting into the top two cylinders. You need to dismount at least the carb bowls on this cylinders and verify there is fuel in the bowl and it is maintained properly by the floats. If the floats are not set properly, the system will run dry. Make sure the floats do not start to close the inlet port until it is at horizontal with reference to the carb's body.

If after the preceding and the plugs continue to stay bone dry, double check there is no fuel blowing back from the top two carbs. If there is, it is an indication you have faulty reeds.