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Discussion Starter #1 (Edited)
Well, my 05 660 just quit on me.

Was going downhill ish, just about at the rev limiter when the engine lost power.

Coasted to a stop at the trailer and she puttered to a stop, idled very poorly for a few seconds and then the engine died. Won't restart and feels like it has very low compression.

When I stopped it was smoking a bit from the vent line at the intake, and it sprays what seems like oil and maybe fuel out of that same vent when I crank it over.

Feels like low compression because the recoil starter pulls way easier than it ever has.

No water in oil at this moment.

I'm kinda leaning toward the engine sucked a valve lol

I don't have a compression tester, and I'm not sure how to get one fished into that narrow spark plug hole, but I'm sure I can rent one from a parts house nearby.

We can start with the diagnostics here, but if I end up correct, is there going to be a good source of a complete top end and maybe go to a big bore kit? If I've gotta do a top end, may as well right?

Thanks in advance for any replies.



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I suspect your diagnose is right. If there’s access caps on the head for adjusting the valves, pull them off and look in there while turning the engine over. Something will probably look odd.
 

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Pull the valve adjustment covers and have a look. The exhaust use a 17mm wrench/socket.
The intake valve cover use a 6mm Allen wrench, and are located under the gas tank. You'll need to pull the front rack, black plastic cover, gas tank cover, gas tank, then white plastic guard under gas tank. You now have access to valve adjustment covers.

Because this happened all of a sudden, I would suspect a mechanical failure like valves. Piston and/or rings would get slowly get worse over time. In most cases if a piston fails immediately (like a broken piston skirt), you get noises like banging, clanging or scraping.

If it were mine, I would probably go right to pulling the cylinder head.
 

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After Rethinking this, before doing anything, first check the spark plug. Make sure its tight and not backed out on it's own. It happens. Very rare, but it does happen.
Remove it and inspect it too. Is there any damage to it?
 

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Discussion Starter #5
Will do so in the morning. I'm beginning to get nervous when I'm near my trailer, seems my wheelers always break right as I get back to it lol

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Will do so in the morning. I'm beginning to get nervous when I'm near my trailer, seems my wheelers always break right as I get back to it lol

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Better at the trailer than 10 miles from it. 😁
 

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Discussion Starter #7
That is very true.

I have noticed the engine has been using some oil. Not much, but I also got some burned oil smell on acceleration.

At 8k miles, it wouldn't surprise me if I need to do a top end.



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Discussion Starter #8
Spark plug is in tight. Valves move when I pull it over with the recoil starter.

Odd. Guess off with it's head!

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Discussion Starter #9
Actually, I'm gonna do a compression test before this head comes off. Just so I'm not going by feel.

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Discussion Starter #10 (Edited)
Compression is 30 psi. So definitely new top end time.

Put oil in the cylinder, compression bumped to about 50 psi.

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Discussion Starter #11
I've got a rebuilt head on the way, as well as a cp 11:1 piston 102 mm with a bored to match oem cylinder, and a cometic gasket set.

I'm stuck on cam selection. Really debating between a stock raptor cam and a mudbuster.

I use this grizzly for snow plowing in winter, yard work in the summer, and trail and mud riding.

Seems if I do the mudbuster I'll get bottom and mid range gains, and only have to change one valve spring, while if I go to the raptor cam, I'll have to change all 5 springs, and should see gains across the board, but least in the low end.

Any thoughts?

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Discussion Starter #12
Found the problem, but really wonder what was the cause.

This grizzly does have highish hours, and was using oil, but not terribly fast.


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Discussion Starter #13
Thought I would add, this is only damaged on the intake side, the exhaust side looks great.


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That's weird, usually the damage would be on the down / power stroke side. .
 

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Discussion Starter #15
That's what I was thinking, usually overheat problems would show up on the exhaust side. Only thing I can think of is k&n filter letting in dirt over 800 hours with poor maintenance?

The cylinder has pretty much no cross hatching. Maybe it just scrubbed the cross hatching on the intake side eventually leading to poor lubrication?

This one has me a bit confused.





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Discussion Starter #16
Further inspection looks to me looks like I ran her low on oil. Level in the crankcase probably wasn't enough to splash oil on the piston well enough.

That's what I get for not checking the oil I guess.

In the meantime, trying to decide if the connecting rod is a problem or not.

Here's some pics of the wrist pin and the con rod. I don't really want to do a bottom end, but I will if it keeps me from throwing a rod lol

The rod doesn't have excessive side to side play and I don't feel any up and down play, all moves smooth through the rotation. I just know the oil path to the wrist pin is kinda crap on these 660s.



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Discussion Starter #17
Took the grizz to an engine builder local and he's off the opinion that I shouldn't need a bottom end rebuild. So for now the plan is to just rebuilding the top end, and improve the cooling system.

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Discussion Starter #18
Took the sheave to Coop45 today. Waiting on parts.

Talking to him about the engine failure, seems I was on the right track about the low oil.

Got my cam in the mail today, still waiting on the piston, cylinder, and head.

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Discussion Starter #19
Got the spal fan today, and the cylinder head.

Let's just say the cylinder head does not impress me.

Rusty valve springs, dirty parts, sand blasted bearing journals.

Let's just say a refund is incoming.


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Got the spal fan today, and the cylinder head.

Let's just say the cylinder head does not impress me.

Rusty valve springs, dirty parts, sand blasted bearing journals.

Let's just say a refund is incoming.


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Crummy. Sorry to hear that
 
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