Logo

Swapping Powerhead 1988 Force 125

Yes, did the link n sync. Adjusted air screws on the water at idle. I left them at 1-1/16th because it didn't seem to make much of a difference when I turned them either way. I'm going to check the timing again, I wonder if the trigger is sticking......
 
Well, I tried to start the beast in the driveway, I got nothin. NOTHING. Got spark, got fuel, got 150 compression. Nothing, not even with starter fluid. Drove myself crazy and gave up. Took it to Performax Marine. They found the problem. The flywheel key sheared, flywheel is trashed and garbage. Crank is slightly damaged. They say (I haven't seen it yet) the keyway has some tiny chips missing on the edges and they won't put it back together because of liability issues, which is fine, I understand ( they don't want their name on it). Anyway, that explains the knocking I experienced when it was out on the water, and why it wouldn't start.

So I am thinking I will put the new flywheel, new key, and new nut back together like this....(please let me know what you think or if you have any other ideas...), I am going to put some JB Weld in the keyway slot right before I insert the new key, and torque the flywheel back on. I think if I can get rid of any slop, if there is any, it might work. Maybe I didn't get the flywheel seated enough or tightened enough? Maybe the new powerhead's crank didn't match my old flywheel good enough? Why did this happen???? Anyone???....
 
You put JB on it and you might not ever get it apart.
Just minor chipping and it should be ok.
Post a pic or 2 Flywheel too.
I have a flywheel if needed.
A backfire or hitting a log could shear the key.
The tourqe is 95# so it might not have been tight enough.J
 
Use some valve grinding compound to lap the tapers together.---This gets rid of minor imperfections.----------------The flywheel is driven by the locking tapers when properly torqued.---------The key merely puts it in the correct position for timing.
 
Thanks guys. I will post a pic when I pick up the boat on Sat. I have a new flywheel for it, I guess the other one is wrecked. They say I will have to remove the trigger and stator to clean up the metal bits.....
 
I took things apart and cleaned it all up. Lots of bits of metal. I also replaced the seal under the trigger, just in case. I used some lite emery cloth on the crank end, I think it looks just fine. The flywheel is wasted. Got a "new" used flywheel, new key, new nut. Put 2 TINY drops of JB Weld on either side of the key and torqued her down. Then went an extra 10 pounds. 100lbs. Started right up. Launched. Idled like crap, white smoke inside of cowling, paddled back in. Checked timing when I got back, the flywheel stayed in place, the timing was still correct, so it would appear that the shearing of the key is now fixed. I think it's a fuel delivery prob. We will see, I took it back to Performax so they can troubleshoot and tune it up, dial it in. I don't have the mental capacity to deal with working on this motor anymore, I will go insane.
It's so weird, that the initial maiden voyage of the "new" powerhead went SO well, and it hasn't ran decent since.....
I took pics, too lazy to post them right now. Will post them when I hear back from Performax and see what the deal is this time.
 
Smoke in the cover?
Might just be where the rubber boot hits the rear cover.It might just need to be moved??
Maybe the gasket between the head and lower?J
 
Picked up the boat today. Right, the exhaust boot to the "power flow" holes had a big slit in it suddenly. Jeez, if it isn't one thing it's another. So the exhaust gets thru the boot and into the engine cover, that equals no oxygen for the carbs, equals run for 3 seconds and die. Problem solved, new boot installed. You know, looking back in this post, I DID replace the inner spring and the endcap, but NOT the rubber boot itself. I should have known better, 20+ year old rubber....
Anyway, Performax Marine solved that problem, and fine tuned the engine! Says it runs like a champ. We will see this Sunday when I try to launch again.

For some reason I can't upload pics of the sheared flywheel key. Will try again later.

Any tricks to putting bottom paint on?
 
Yes.
Bottom paint will just peel off if the bottom isin't prepped.
The cheap way,100grit sandpaper.
The easier way.They make a bottom paint that etches the fiberglass.
Just roll it on and let it dry and paint over it.
Most bottom paints are not good to paint on aluminum.
Some have copper and it reacts with the other metals.
They sell an outdrive/outboard paint.
The way most outboards are mounted a bit of the lower will be in the water.
And part of the transom mount too.
Go to the Interlux site and read all about painting the bottom.

I don't like leaving the older Forces in the water as there is no way to flush them.
If you use the motor a lot it's not so bad.
Salt builds up and makes a mess.J
 
Well, took the boat out. Ran FLAWLESS for a combined total of about an hour and a half. On the way to the ramp, I started getting a high speed miss. Over about 2 minutes, I thought I heard something, then I was sure I heard something, then it started to miss a little, then a little more, then just kind of stayed there. I ran it almost WOT for about 2 minutes to get back to the ramp. Of course I wasn't going as fast as normal WOT. It was running, but intermitently missing. At the ramp it was idling fine. NOW WHAT?!?!?!?!?!?!?
 
Talked with my mechanic today. He suggested check the compression ( it has read 150 x4 consistently, but I'll do it again ), change the plugs to a different number than the ones I'm using, and give it a test ride. Fuel is good. He said if it were a coil it wouldn't have been an intermittent miss. I agree with that. If it is a weak plug, could it have started missing in the timeframe of about 2 minutes after running good all day? I guess what I'm asking is, can the plug just go south like that suddenly and not fire all the time? or can it turn weak that suddenly?
I haven't had time to visually check the plugs yet....opinions????
 
Last edited:
Possible loose connection.
Check all grounds(coils).
Coil could break down at temp.Not very likley.
Check bussbars for loose wire.Pull on each one(gently)
UL-18V or the Jap plugs.
I've done this since 1985 and have never found a bad plug.
Not saying you don't have one,but again not likley.
Post comp #s and what plugs your using.
You don't want a too hot plug in there.
Possible? Dirt in carb,water in fuel.
All nuts and bolts tight?Sucking air around the carbs,intake?
 
Check out the plugs. Look at #4. Remember, it ran great all day, the last 5 minutes to the boat ramp it was missing every 1 to 2 seconds, kinda of a burp. Obviously #4 looks different, like something dripped from the middle of the plug (unburned fuel?) It also took a sort of hard rub with a towel and finger to get the dirt of the plug, but it came off and looks fine. Compression tested again, 150 all 4. Started right up in the driveway and purrs. Plugs are ngk BUHX, gonna switch to ngk B9HS 10. Maybe this week I'll get it in the water for a high speed test.

I also attached the flywheel shear pix. (by the way, I marked the new flywheel, nut and crank when I installed them, nothing moved after the day on the water, I think that issue is solved.)
 

Attachments

  • plugs after hi spd mss 5-5-12a.jpg
    plugs after hi spd mss 5-5-12a.jpg
    62.2 KB · Views: 127
  • 101_0271a.jpg
    101_0271a.jpg
    52.2 KB · Views: 112
  • 101_0273a.jpg
    101_0273a.jpg
    64.8 KB · Views: 114
  • 101_0274a.jpg
    101_0274a.jpg
    63.9 KB · Views: 116
Last edited:
New plugs.Then check the fuel for water?
Fuel: loose connection on fuel lines?
Pull carbs and check the reeds.
Check the fuel pump.
Overheat buzzer working?
 
OK, put in the new B9HS 10 plugs, they are a "j" type. Cleaned small amounts of rust off the ground connections on the coils. Have been out TWICE now with NO ISSUES. Engine performs flawlessly, starts like a new motor, runs like a new motor. On my 16' capri, this 125 is very smooth. Awesome, did it. Thanks.
 
And still running like a freaking champ after 3 full seasons and still has 150lbs compression on all 4! Replacing the starter tomorrow....
Amen to non-ethanol gas!
 
Last edited:
Back
Top