96 SPX replace entire engine or hopefully top end?

[96spxpos]

ok, update, finally got a little wrench time in to get to breaking down this salt bar.. I piston circlips all look in tact so that's not what did it. the debris you see on the pistons is mainly just surface debris from me drilling THE HELL out of the bolts to get the head cover and head off, so that'll all be cleaned and flushed. The mag piston head has some tiny circular pitting around the edge. If there was no broken ring/debris inside the top of the dome, what would cause this? The PTO piston has some carbon build up, but appears to wipe off with ease. the piston sides are both fairly smooth with no pitting. a little discoloration here and there, but otherwise pretty smooth. the jug walls look pretty good with no major scoring/etc, so the issue is obviously the bottom end. before trying to move the pto anymore, I decided to wait till I flush the bottom end out in case theres any metal or brass chunks down there and I don't want to create any more damage. either way, unless I get a new set of jugs and seriously sandblast the hell out of the entire casing, I don't know if id even want to use this casing/core again bc of all the corrosion.

 

[96spxpos]

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[96spxpos]

I also noticed on the mag piston, the bottom ring is loose and on the pto piston the top one is loose. Is that normal!?


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[AdamXP800]

I had a needle bearing put damage really similar to that on a piston in my XP



95 XP800!!!
Keep the 2 strokes alive!

 

[CReynoldsMIZ]

I had a needle bearing put damage really similar to that on a piston in my XP



95 XP800!!!
Keep the 2 strokes alive!

Something got on top of that piston and it ate it for sure. Ive thought for a while on this point that there wasn't really a reason to break it down. I think your going to be better off just cutting your losses and get it rebuilt with a warranty. This motor is toast.

 

[96spxpos]

yea, well ive never completely opened a motor before so it was something I was interested in doing to get to know the in's and outs of these skis. after all, this is the place for information and education. On that note... do the circlips need to be broken out/busted for a needle bearing to come out/loose?

 

[1of500]

Pic of the inside of the head please

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[1of500]

How much carbon was on the pitted piston. Looks like it was lean has had some detonation going on

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[96spxpos]

yea, the pitted one didn't have no where near as much carbon as the PTO one did. and....you don't want to see a pic of the inside of the head....trust me... (I'll take a pic for you anyway when I get home)...Between the torch, the 3 screw drivers and the crow bar and all the corrosion, I don't know what is the worst...lol

 

[96spxpos]

[MENTION=73220]1of500[/MENTION] here are some pics.. Notice the fresher, deeper scratches under the domes are from the crowbar I used.. I've seen this on other domes too, but why does one look shiny/glazed while the other one looks almost chalky?and yes I merked that head cover with some drillbit Taylor's..

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[1of500]

It's the pitting. Iirc you let someone ride it and they where barely giving it any throttle for a long period of time? Looks like some detonation to me but I could be wrong I have been before.

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[1of500]

Probably was just a hair lean on the low side just guessing

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[1of500]

Detonation

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[96spxpos]

Detonation

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So strange how the surfaces can be completely different in two cylinders... so detonation...

 

[1of500]

Or just lean

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[96spxpos]

I'm hoping to spend a little wrench time on it late night tonight. Curious to see the RV brass gear. To get to that first, can I just remove that C clip retainer and slide the shaft out, or do I need to have/make one of those tools (I saw one made out of a PVC end cap)? Or do I have to remove those 8 or 12 or 16 bolts or whatever from the bottom end to split the case to remove the RV?


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[1of500]

You remove the clip then pull it with the puller you are referring to

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[1of500]

I would split the cases though that way you can check out the gear on the crankshaft too

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[CReynoldsMIZ]

I would split the cases though that way you can check out the gear on the crankshaft too

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+1. Agree on thay

 

[AdamXP800]

+1. Agree on that.

+2



95 XP800!!!
Keep the 2 strokes alive!

 

[96spxpos]

And the WINNER IS!!!!!!...............


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[96spxpos]

[MENTION=60330]AdamA96XP[/MENTION] ! Needle bearing lodged on the side of the casing, recovered two needle bearings that were about half size, so it was probably 1 split in 2, or 2 split ones and I haven't found the other two broken pieces.. So... Long and short of it.. Ate a needle bearing..

What causes this? Old age? The Piston rods had virtually no left to right play.

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[AdamXP800]

Your piston looked identical to mine. Those round holes punched in the piston



95 XP800!!!
Keep the 2 strokes alive!

 

[96spxpos]

Ok, so, how many needle bearings go in each piston on the 717? Obviously I should have an even number at the end, but I think I've heard like 28 or 34 in each one. I wound up with 60 total, 30 in each.. I'm just curious as to whether or not I'm missing some. Remember, this is the 717 motor.. I read somewhere that the bearing amount can also depend on engine size.


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[96spxpos]

Bump...
Does anyone know?

Thanks!