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'89 Evinrude 100XP Broken Ring - Options?

jasonWA

jasonWA

New member
Hi Gang,

Weekend before last we were out messing around on the river when I noticed that the boat was way down on power. She wouldn't get up on plane. We limped to the dock. Once home, I did a compression test... about 90 on all but the top right cylinder. That one has 60. Pulled the head and this is what I see. I'm looking for advice on my options:

(1) Repower the boat. Seems like this is at least maybe $5k for a decent used motor... And I still won't really know the history of it.
(2) Dismantle, bore out 0.020 and rebuild. A bunch of work for such an old motor.
(3) Hone that cylinder and install new rings, hope it seals better? Bore out that cylinder only? Other "cheapskate" options?

I lean towards option 2. At least this way when I'm done I know exactly what I've got, and I'm pretty comfortable doing it myself. But some people say these old motors aren't worth it. Maybe a replacement powerhead can be found somewhere? Any suggestions on this?

Thanks!
Jason

Edit: Model number E100STLCEM
 
I suggest 4 new pistons.-----The fault is the shape of top ring.-----Perhaps find a good used block.----I can't count as to how many of these powerheads I have in the shed. -----Well worth doing , if you do it yourself in my opinion.
 
faztbullet said:
.020 wont clean that up...
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Thanks for the quick reply. I thought I'd seen 20 over pistons before but it looks like 30 over is the way. You think that'd do it or is this block toast? I suspect we never go 60 over with these, is that correct? Sleeve it maybe?
 
racerone said:
I suggest 4 new pistons.-----The fault is the shape of top ring.-----Perhaps find a good used block.----I can't count as to how many of these powerheads I have in the shed. -----Well worth doing , if you do it yourself in my opinion.
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Thanks for the reply. Is the problem fixed with aftermarket rings? I see you guys posting elsewhere that these motors always suffer from broken rings. Looks right. Suggestion on a source for a good block? You want to sell me one?
 
Your location?----E-bay likely has lots.----Need both parts.----If you could walk over to pick one up it would be no problem.
 
racerone said:
Your location?----E-bay likely has lots.----Need both parts.----If you could walk over to pick one up it would be no problem.
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I'm in Washington State. Guessing you're at the other end of the country? I've been looking on eBay, but am having trouble being sure that it's the right powerhead. Example: eBay Powerhead. I'm having trouble believing the powerhead is the same for all '78 through '97 85, 90, 100, 112 and 115 crossflow engines. Is it really?
 
Why would you not believe they are the same block ( very minor differences ) for all those years to 98 Which was the last year of these very well built engines.----Except for the top piston rings of course.
 
racerone said:
Why would you not believe they are the same block ( very minor differences ) for all those years to 98 Which was the last year of these very well built engines.----Except for the top piston rings of course.
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First, I would have guessed that the horsepower range would have included more than one displacement. Reading through other threads, though, it sounds like the main difference (or in some cases only difference) is the carbs? Apparently they're all the same displacement? Also sounds like there is sometimes variation in the exhaust geometry, especially the exhaust housing (leg)? I guess you're suggesting though that none of this is relevant if I just need a good block.

Second, I'd be surprised if there were no changes to the block design that would be a problem for compatibility over that large a span of years. I really don't know, though. That's why I'm here.
 
Same pistons fit from 1974 to 1998 models !!----Carburetors use different bore size.---The 88 / 90 models have smaller intake ports.----135 ./ 140 models and newer 110 / 115 models used the tuned exhaust.----That bubble on the back of the block.
 
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