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Discussion Starter #1
I'm running 370's on my ultra with decker pipes. I took the plugs out after 2 runs in a field and this is what they look like. The temp was 1 degree out side. I think I might be alittle lean but im not sure. Please help! I think that it might be causing the bog at 5000 rpm. The order is 1,2,3

[attachment=59559]
 

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Honestly I can't get a good look at those, but they appear a bit lean to me.

How's your wash? Spend the $7 at Murray's and get a little bendy-light thing if you can't see it.

IMO Wash is a better indicator.

Plugs are affected more quickly, but are also more easily affected by the type of oil you use (Synthetic, mineral, or blend)

Bryan
 

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I don't know? Do I look at the intake or exhaust side of the piston? I am running synthetic. I'll go look. Its cold out there.
 

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I looked at the piston and didn't see anything but carbon. I need to get one of those lights to look better.
 

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370 straight across ? You should stagger one size leaner in the middle. Need more of a sideways view of the electrodes to ck for a lean condition. You say bog at 5000, does it lay down when you stab it and is it worse the warmer the engine gets?
 

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It's hard to tell the color exactly from a picture. You are also looking at where it's colored as well. You should be dark toward the bottom of the ground electrode and then getting to a light brown color toward the end. Plug color is a much quicker indicator of jetting. Sometimes plugs may indicate one condition and piston wash another, but what is really happening is that plugs change quick enough that at idle they may go rich or lean, usually rich, before you shut it off and pull the plugs. You should shut the motor off in the throttle position that you want to check to get the most accurate reading. This means shutting the motor off while the sled may be moving at 40 mph for example. If you just want a quick and dirty check, shut the motor off immediatly after you stop your run. Yes, you should be one size leaner on the middle cylinder on that motor. Here is a jetting article that I always recommend reading. It also has a little bit on piston wash. It's worth the read and should help ya out.

http://www.snowtechmagazine.com/articles/2001/baseline/baseline.php
 

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Originally posted by snake61047
[br]I looked at the piston and didn't see anything but carbon. I need to get one of those lights to look better.
You need to check the outside edge of the piston when it's at BDC. If there are no bare-metal spots showing (as indicated by that nifty article posted above) across from the transfer ports, you are lean. General rule of thumb is you want wash about the size of a pinky nail.

Bryan
 
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