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Reverend Dennis
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Discussion Starter · #1 ·
Ok guys, got the AC 580efi back together, new wiseco piston, new gaskets, etc.

What is the proper break in for this? I also replaced the belt, so far have let it warm up nice and toasty, then turned off, let cool. then restarted, did that like three times.

Then for the first 10 miles, only went about 20-25 mph, varying the rpm's. For the next 20, moved up to 30 mph varying the rpm's and the next 5 miles went to 35-40 mph

How long should I do this? I read somewhere like 2 tanks of gas, BUT on the EFI that would take forever on this thing
 

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Don't forget to re-torque the head bolts. The big thing with Wisecos is warm up before riding. I would start and idle the sled until you feel heat in the exchangers, then shut it off and let it sit. That way, the block and the pistons get to the same temp. Finish dressing down, then ride. Forged pistons will expand at a different rate than the cast block, so if you get the whole engine to operating temp, the chances of damage caused by a cold seizure is less.

It sounds like your procedure is safe, I would continue at least until that first tank of fuel is gone, always being aware of warm-up.
 

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Reverend Dennis
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Discussion Starter · #3 ·
Thanks Dan,

I have been letting her warm up nicely. Usually start it, have a smoke, finishing dressing then start her off slow.

As for the break in, this thing get great mileage, being an EFI, I would have to say a full tank on her would be around 150 miles at least, thats not a little overboard on the break in?
 

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Reverend Dennis
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Discussion Starter · #4 ·
HELP figured it out!!

Ok well took her back out, let warm up 10 mins, started real easy, little burb hit 40, and then suddenly loss power, sled almost died, powered up and felt funny, sputtered, So I killed it and inspected.

Turning it over by hand felt a slight grinding in the cyl. Dumped a little oil down the cyl and restarted and babied it to shop. Checked compression suddenly what was a solid 130 yesterday, was now 115!

Slight scoring all around the TOP of the cyl. Not just in one spot. Looked at it closer and noticed this!

This is what caused the first piston to blow out as well! Major pitting all over the head! Now I have to replace the head before even attempting to ride it again! at 115-120lbs it would be ridable but not what it should!

34 miles on the break in and its dead again! I am about done with this sled!

Any thoughts on that head?
 

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That stinks. Any damage to the piston crown? Could be detonation, what octane gas are you running and is it alcohol fuel? Doesn't look like a foreign object unless you have similar damage on the piston. Is there any damage to the cylinder or to the piston skirts?
 

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that blows i guess we aint ridin later ill have my track back in in bout and hr.
 

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Reverend Dennis
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Discussion Starter · #7 · (Edited)
That stinks. Any damage to the piston crown? Could be detonation, what octane gas are you running and is it alcohol fuel? Doesn't look like a foreign object unless you have similar damage on the piston. Is there any damage to the cylinder or to the piston skirts?
Nope, piston crown is ok, nice burn pattern even. Dont know about the skirt but the cyl has light scoring around the entire circumference, but only on the top.

Fuel is 87 oct, non alcohol, (well the typical 10% ethonal here, but all our fuel has that here)

Going to try to find a new head and run it like it is. Honestly I am not willing to put anymore money into this now, and if I have to have the cyl replated, I am going to say the heck with it, wait til summer and replace both cyl's and pistons back to stock, screw this overbored shit.

I mean due to that head, I already had to replace the piston and wait 2 weeks to get the cyl replated..
 

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what happened to make you put a set of wiseco's in it ?
what i am getting at is; if you had a piston failure , you need to be extreemly
diligent about cleaning up the engine BEFORE you put it back together.
i had a friend who put a new set of pistons in an engine and it didnt last two trips .
i took it apart and sat there for two hours cleaning and flushing and spraying solvent and sucking it back out and cleaning and cleaning , it takes quite a while to get all
the debris out of there ! just wondering if this was your scenario?
 

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Reverend Dennis
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786 Posts
Discussion Starter · #9 ·
what happened to make you put a set of wiseco's in it ?
what i am getting at is; if you had a piston failure , you need to be extreemly
diligent about cleaning up the engine BEFORE you put it back together.
i had a friend who put a new set of pistons in an engine and it didnt last two trips .
i took it apart and sat there for two hours cleaning and flushing and spraying solvent and sucking it back out and cleaning and cleaning , it takes quite a while to get all
the debris out of there ! just wondering if this was your scenario?
I bought it this way, it was already bored over, dont know why.

I had to replace the piston because suddenly the rings went bye bye on it, and scored, gouged the cyl. Had the cyl replated and repaired.

I am thinking the head pitting and chipping might have been the cause of the first piston failure, as well as this one now
 

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You may want to run 91 octane as well. Cat recommends increasing the fuel if you're running 10% ethanol. On the carb engines, the recommendation is to jet one step richer to compensate. On the newer EFI's, there is a jumper wire you connect to richen the mix when using the ethanol stuff. About all you can do without the jumper on the older EFI's is to run higher octane.
 

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Reverend Dennis
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Discussion Starter · #11 ·
Well season officially done, and I am done with this sled.

Drove an hour and a half last night to pick up a new head for it. Put it on today, checked compression right at 120. Great.

Let her warm up started out slow and easy, eased up to 45 and then shut down. Towed her back checked compression, maybe 60! cold she will start right up, but once warmed up, compression drops to next to nothing, and will stutter bad, one cyl firing. Barley enough power to pull into the shop.

The scoring must be bad enough that once warmed up and expanded no compression. Cant afford to have it redone AGAIN, not to mention the time, season will be winding down.

Not to mention I can not buy just the rings for this piston, they sell every other size for wiseco's but the 76.4!

If I had the cash I would jujst replace both jugs and pistons and go back to fricken stock.

Well hope everyone else has a good rest of season, maybe next year I'll be riding..
 

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this sounds more like a stuck ring. as cold the seal is good and tight to the ring but as it warms up the cylinder is expanding and not the ring. a way that you can test this without pulling the jug is to move the piston untill the rings are visible in the exaust port and push on it with your finger and it should be springy if not could be carbon or foreign particle jamed in the ring groove causeing the ring to stick

not certain but something id check
 

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I would like to thank everyone here, this has been very informative and helpful. I've been looking for info on engine breakin process and this is all I wished for.
 
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