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Discussion Starter · #1 ·
Just fishing for some info. Ive got a 06 660 bored to a 686. It spends most of its time in the sand at about 3'500 '. I dont drive it like I stole it. A reputable builder built it. Its only got approx. twenty hours on it. We were running it around on small rollers going easy on it and hit the flats and opened it up. I didnt have it pinned at all and noticed it was losing power. We tore into the top end due to loss of compression. We found that it lean siezed on the intake side of the piston. Im running an open box with a K&N, 165 main jet, two brothers dual exhaust and a stock fuel pump. The boot on the carb/intake is in great shape. Any ideas? I'd be happy to provide more info if it helps. Thanks
 

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do you run an outerwear or just the straight KnN?,,,,,,,,,,I think a 170 jet on a stock carb is closer to a 13.5 AF ratio..........but lack of fuel can be from clogged filters,too small main and needles and pilots too, you can experience a lean signal throughout the running band also not just at high rpm.....How eggshaped is the bore? Just some exploratory questions I would have prior to pointing a finger...todays gas starts solidifing in three months, wonder if your main has lightly clogged enough due to bad gas to limmit the fuel signal enough to lean it out say 20%, that could spell a lean burn issue???
 

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Discussion Starter · #3 ·
Clogged main??? Could be. Todays gas is CRAP. Any reason I might need an aftermarket fuel pump?
 

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no on am pump

you don't need an aftermarket pump,the stock pump returns probably 40 percent to the gas tank un used, so unless you are making 100hp at the crank and found the holy grail of rhino engine building secrets you will have plenty of fuel with the oem pump...
 

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Cameron is correct with regard to the volume of a stock pump in good condition is more than enough for any rhino motor period...

Volume capability of the stock pump in good condition that is not overheating is never the problem with fuel delivery....

However, if you are having overheating problems and/or have a worn out pump and going to buy a new one it is much better to get a good high volume fuel delivery kit at that time...

Our fuel delivery kits for both the stock and high volume pump are good thing to have and are extremely useful for sorting out other run-ability problems regardless of the cause...

First of all...even with our most basic kit for the stock pump you have the ability see where fuel is and isn't including the ability to see what the fuel level inside the float bowl is...and will allow you to pressure test your float too if you have a gauge and a bulb primer...all of our kits are available with bulb primers at this time....
 

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I have damaged lots of pistons because of lean mixture or improper timing, but I dont think you could have seized it from running lean, it is probably seized from detonation.............
 

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Discussion Starter · #9 ·
So its back together and running good. The cylinder just needed to be cleaned up. New piston and rings. It runs great. It seems to start easier than before this incident. Is it possible the timing could have been off enough to have made it run hotter and cause a detonation issue?
 

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teeth

had one a tooth off,never ran hot,was just hard to start/crank....stretched chain thru me off when i timed it....note too self,put engines together in the morning,not the night...
 

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Discussion Starter · #11 ·
ok, scratch that. What about this, might be kind of a far stretch. Try to follow me here, where the fuel line goes behind the pass. seat and under the rear part of the center consol is it possible when you have a passenger using the center console as a arm rest or leaning on it, could it cut off some of the fuel supply to the carb thus making it run lean? I know this is a stretch but Im trying to figure out why it did what it did.
 

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It would have starved for fuel and died... Sounds like a Compression Ring issue..
 

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Discussion Starter · #13 ·
Yah, after I thought about it, that seemed like a long shot. So, compression ring. Please explain.
 

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By what you have described it Could have been a broken ring around the piston. Loss of compression is loss of power. Since you have cleaned it up and installed a new piston and ring set and it runs great and starts better, I would lean that way. Did you look at the rings to see if they were broken?
 

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Discussion Starter · #15 ·
The rings were in good shape except were the piston burned. It burned on the edge of the piston and ruined the top two rings. Not sure if that explains it. I can take a pic of the piston and post it if that helps.
 

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Detonation that comes nearer to TDC or slightly after will likely result in the burning of the piston or the lifting of the rings from the piston.

Auto Ignition usually occurs around the edge of of the piston, especially if there are any edges that get super heated (glowing) that ignite air/fuel before the spark plug does.

Anything that will raise temperatures in the cylinder will help promote detonation. This rise in temperature could occur many different ways: very lean air/fuel ratios, heating of the charge air prior to entering the combustion chamber, or poor heat dissipation through the cooling system.

I would check both the cooling and fuel system to make sure they are functioning correctly.
 

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Oil getting into the combustion chamber will cause detonation too. One more thing to consider.
 

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Oil getting into the combustion chamber will cause detonation too. One more thing to consider.
I have never heard of this before, and do not understand how this can happen, please explain how oil can cause this...........
 

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ever heard of a multifuel engine, check'm out-they can run on engine oil,gas,diesel,ATF,karosine,just about anything it can push through its injection pump, and guess what-it self ignites too..........military use to run them all the time....pretty cool..
 
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