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Rich or Lean, or ? Piston pics.

T

ttreewalkerr

Free Member
These are my 05 piston pics before removal. Sled ran good all season. Changed them to 06 pistons for reliability,, nothing wrong,, cylinders were good.

TPS set on high side, .714 T.P..Closed.
10.5 MPG
7350 WOT
All stock, gutted stock air box.
Original fuel filter, 2,200 miles. (Just cut it open, nothing visible)
Burns approx. 1 quart oil per tank, maybe little less.
No belt issues,, Michigan flat land trail,, aggressive.

Rich, or Lean ? I've always assumed rich due to dark exhaust on plastic exterior.

2011 sept 26 001.jpg 2011 sept 26 003.jpg 2011 sept 26 005.jpg 2011 sept 26 006.jpg 2011 sept 26 008.jpg 2011 sept 26 007.jpg
 
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What kind of oil?

Race gas?

That is VERY small wash at 6:00 and at 4:00 position of that picture.

attachment.php
 
slash925 said:
too much carbon to be lean
Click to expand...

Well thats why im posting,, if i read different opinions,, some people say black carbon means it's not getting enough fuel to wash it,, etc..

Look at the bare spot in middle,, what the heck does that mean ?

There is no pitting on piston, or in cylinder. Metal is all good.
 
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Why are you running Dominator? I would say wrong oil and pump sticking. Do you have and FBF cable or stock cable. You also might want to do the pump spring mod.
 
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Z-Man said:
Why are you running Dominator? I would say wrong oil and pump sticking. Do you have and FBF cable or stock cable. You also might want to do the pump spring mod.
Click to expand...


I use dominator for most of season,, then Interceptor for last ride.. So thru summer it has rust prevent in it,, and i fog.

What would be the issue w/ Dominator ?
(I know it has reduced rust prevention, but better lube)




i just did a new top end, and got to inspect oiler cable and spring,, all looked fine,, snappy and no sign of wear.. Oiler cable looked new.. i did allot of staring at it w/ my kid working throttle,, i didn't see any problem with it's action. All stock cables.
I do send a shot of Spray lube into oiler cable tube doen by primary two times or so during season,, just cause all i have read on how bad this cable is. It does seem like it's a plastic cable or somthing.. It looks fine though.
 
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Not sure why you would think Dominator was better lube? Interceptor is made to run cleaner and for use with exhaust valves. Even sitting in your trailer during the season your engine gets condensation inside it too, so rust protection is a must. Indydan has had several posts about engines failing because of this. I personally had an indy 650 engine fail because of rust from sitting.

interceptor
http://www.amsoil.com/storefront/ait.aspx

Dominator
http://www.amsoil.com/storefront/tdr.aspx
 
I'll say its a little lean. Exhaust is pulling the carbon off by the exhaust port a bit and the funky spot in the middle is where the lean burn gets really hot before it melts a hole in the piston.

If it was carbed, I'd richen one or maybe even 2 jet sizes.

sled_guy
 
I disagree, you are getting carbon build up which is usually an indicator of to much oil. The entire top of the pistons in mine were nice and clean, you could even read the markings on them. The clean spot is from the plug firing, but it is not because it is lean but because it is the only place not getting carbon build up. In a 4 stroke this might indicate bad rings but not sure if the same holds true in a s stroke because bad rings do not let oil into the cylinders, it is already there.
 
Z-Man said:
I disagree, you are getting carbon build up which is usually an indicator of to much oil. The entire top of the pistons in mine were nice and clean, you could even read the markings on them. The clean spot is from the plug firing, but it is not because it is lean but because it is the only place not getting carbon build up. In a 4 stroke this might indicate bad rings but not sure if the same holds true in a s stroke because bad rings do not let oil into the cylinders, it is already there.
Click to expand...

I agree with this, i've rebuilt a few 900 motors and 7 and 8 motors, Never seen that much build up on a piston before. I've seen a light (non-crusty) coating on pistons but never a think nasty coating like that. To much oil is what it looks like to me. I've seen 4000+ miles on pistons that look better than that.
 
I'm with indy dan on the oil. I think I'll ditch the expensive synthetic and fancy oils and go old school with mineral oil, Clean my valves once a season and put 250mL's of oil in the tank as insurance and better bottom end longevity.
I think that's about 1/2 cup in american..!
 
look like some one was driving like a ***** and got it carbon up or running to much oil with the gas and look like it lean at wide open and someone keeping it wide open and maybe getting high rpms
 
Those were my 05 pistons,, got the 06 in there now. Took pipe off and looked in,, same carbon.

Max. 7350 RPM WOT,, runs great.. 10.5 MPG , 1 quart of oil per 10 gal. injection only.
I ride Mich. trail,, sure WOT, but usually only for 3-5 sec. then back off due to im where i need to be for turn.

Got my TPS set for the high tolerance side, which would make it run rich if anything.
Amsoil Dominator used. Maybe carbon from that,, but hey,, 2500 miles and all good, im not complaining.
 
05 tmk 900 said:
I'm with indy dan on the oil. I think I'll ditch the expensive synthetic and fancy oils and go old school with mineral oil, Clean my valves once a season and put 250mL's of oil in the tank as insurance and better bottom end longevity.
I think that's about 1/2 cup in american..!
Click to expand...

then your pistons will definitely look like this.
 
I think running oil designed to burn cleaner would help. Running oil designed to be used in engines that get torn down after the race not helping.
 
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