Down under rebuild of 90HP Force

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hundee r1

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Re: Down under rebuild of 90HP Force

thanx JJ, your answers have been greatly appreciated.
Yes, get it running, wouldve happened last weekend, but got side tracked and went fishing with my buddy, we didnt do to bad:







This weekend tho, all going well by sat arvo she will be rumbling on muffs in the back yard
 
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hundee r1

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Re: Down under rebuild of 90HP Force

2 turns of the crank, and voila:



Had it idling for 10 mins or so, havnt touched the tune yet, just checked the cranking timing, promptly comp tested it and its at 130psi dead even on all 3. I expect that will get better.

Its a miserable wet day here today so left it at that. next will be a full carb/timing sync as per Franks threads and u tube vids and then get it wet next week!!
 
jerryjerry05

jerryjerry05

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Re: Down under rebuild of 90HP Force

I just did rebuild on a 125 for a guy in another state.
He sent me a pic of it running.
Always good to know you did something good:)
 
H

hundee r1

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Re: Down under rebuild of 90HP Force

Finally got the chance to take the boat out for a test drive today.Was going great, but unfortunately about 3km up the river, we heard a slight whine in the motor. We backed off and it disappeared, then re appeared. I throttle back a bit and it went away, boat starts slowing down on its own accord, I go to neutral and the thing stalls. Never saw more than 3000rpm

I tired restarting but all I got was a click. Cover off, motor is clearly seized :(

Me and my buddy pulled it down straight away once home, I've attached a photo of the culprit. The upper crank bearing has destroyed itself!!!

All had been going so well since the initial hicups!! Not real happy and kicking myself for not leaving the old one on!!

 
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hundee r1

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Re: Down under rebuild of 90HP Force

pnwboat said:
As stated by Frank and Jerry, if the top bearing is OK don't mess with it.
Click to expand...
wish Id listened to this, but figured I have a new bearing, the old is 20 years old, just swap it over....:facepalm::facepalm:


Im already thinking of how Im going to put it back together. I have a question for you experts.
Atm, the block still has the head and pistons installed.
my question is, can the pistons retract far enough into the head ( whilst not connected to the crank ) so that the rings are no longer captive in the bore? Be nice if it cant happen so I can attempt at piecing it all back together without removing the head & pistons.

upon assembly I found it quite tricky to instal the crank with all 3 pistons in place, so installed the crank , then 1 piston at a time.
But If the piston crowns touch the head before the rings fall out I might try again.

Thanx guys.

Wish Id put this thread to rest today :(
 
jerryjerry05

jerryjerry05

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Re: Down under rebuild of 90HP Force

Don't remove the head. Just install the crank.
The pistons will have enough wiggle room to install the crank without too much trouble.
No way the pistons are gonna go far enough towards the head to let the rings get loose.
Can I say: told U so:) Kidding. Just glad it wasn't any other parts that siezed.
The new bearing. Grease it a bunch before it's covered.
 
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hundee r1

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Re: Down under rebuild of 90HP Force

Ok, old bearing had to be removed by an angle grinder, 10t press wouldn't move it. It had actually moved 2mm up the shaft, pushing the crank down ! Must've happen right on nip up. Crank kissed the inner of the case and the bearing touched the upper seal.
Bearing manufacturer can't explain why it failed.
I didn't lube it at all upon assembly, and maybe add some debris in the race from install and I'm hoping its the cause.
New bearing went on in a press this time. Again with loctite, and the powerhead is once again assembled (much easier second time).
Local shop have no answer nor do Powerheadkit.com, seems no one has seen such a failure, all I've been told is to pack it with grease as jerry stated.
Anybody else want to chime in?
 
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pnwboat

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Re: Down under rebuild of 90HP Force

I've only replaced that bearing once on a motor, and that was just because the owner insisted,.... the old bearing was fine. I have seen the bearing shift on the crankshaft like what you experienced but never actually fail. I would suspect like you mention, that some debris got in there, or maybe the bearing itself was defective.

Anyways, any lubrication is better than none. Whether it's used or new, I pack it with some grease and pour some 2-stroke oil into the bearing just before I install the upper crankshaft bearing seal/plate.
 
jerryjerry05

jerryjerry05

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Re: Down under rebuild of 90HP Force

Glad it's going easier the second time around. Just make sure the bearings, seating all the way in.
Put the seal on and make sure it clears?
 
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hundee r1

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Re: Down under rebuild of 90HP Force

Ok, so last night I had some buddies come over and brave the cold in my garage, I paid in beer n pizza, they helped me finish the build off. Like clock work, within a couple hrs the motor was fully assembled, comp tested , timed and ready to fire up.
Rained all morning but stopped in the arvo. Rolled it out the garage and fired it up.15mins on the muffs and back to the river. Windy and choppy,no one else boating, so we launched at a ramp with the wind blowing 25knotts on shore, just in case. Spent just over an hour in close vicinity,just doin laps, slowly up the revs. By the end of our session, it hadn't missed a beat, no more than 3200, but it feels great and I was able to drive it back onto the trailer!!

Much better result this time around, thanx again guys!
 
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pnwboat

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Re: Down under rebuild of 90HP Force

Congratulations to a job well done Hundee!
 
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hundee r1

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Re: Down under rebuild of 90HP Force

Just a quick update, done about 4 hrs on the build now. All seems to be going good.

Ive done a tune and sync, made sure I have full throttle and rebuilt the fuel pump, spark seems good.

I havnt tried for too long nor revved it past 3500 RPM, but I think the revs will still max out at 4000-4100RPM ( the original reason as to why I embarked on the rebuild) and probs not much over 50km/hr.

I still consider this to be un acceptable for a 90HP motor on a 17ft boat.

I will be rebuilding the carbs ASAP just to eliminate them, but Im still thinking a prop swap is in order.
 
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jerryjerry05

jerryjerry05

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Re: Down under rebuild of 90HP Force

Do a comp test.
Then what prop?
You sure the tach is right?
The speedo too?
 
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hundee r1

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pnwboat

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Re: Down under rebuild of 90HP Force

Kind of a long shot, but have you tried disconnecting the stator leads to your "universal" regulator (which doesn't seem to be working anyways) to see if that has any affect? This is one of the steps for trouble-shooting ignition related problems. See page 27. Section titled "WILL NOT ACCELERATE BEYOND 3000 - 4000 RPMs".

CDI Electronics Practical Outboard Ignition Troubleshooting
 
H

hundee r1

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Re: Down under rebuild of 90HP Force

^^^^ yeh, I had read that, but its kind off miss leading in the sense that it reads as if the motor is missing at 3-4000rpm and thus not revving. Mine doesnt miss at all, just doesnt rev any more.

Im assuming you guys think the 13.25 x17 should be right for the combination?
 
jerryjerry05

jerryjerry05

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Re: Down under rebuild of 90HP Force

That prop should be close to what you need.
Try going for a ride,cover off.
Then accelerate and see if it works.
Then have some one drive as you push the linkage by hand.
When your running it do you have it tilted up?(power trim)
 
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pnwboat

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Re: Down under rebuild of 90HP Force

Before you make a final decision on whether or not it will rev any higher, wait until after you gone through the break in period, just give it a whirl and see for sure.

If it still won't get past 5000 RPM's then there are a few other things to check. Like Jerry said, the prop you have should be pretty close to what you need. My manuals indicate that your motor has kind of a unique stator as far as the Force motors go. It has a low speed winding, and a high speed winding. I've seen quite a few of these stators with a bad low speed winding. Symptoms are... very difficult to get started, won't idle or stalls a lot, but once started runs fine at higher RPM's. I wonder if you actually have the two speed winding stator, and if so, is the high speed winding bad or going bad. Easy to check with your meter. What color are your stator wires?
 
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