reddish looking spark plug

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#1
the plug on my yz125 has a reddish color on the electrode and the insulator. when i got the bike it had an 8 heat range spark plug and was too rich. after the rebuild i put the stock 9 heat range plug in. i havent done anything with the carburator. the bike is really hard to start cold.
is this normal?

suggestions?

thanks.
 
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#3
well i dropped the clip one position on the needle today just to see what it would do.. the plug was black accept for just the tip of the electrode was white. i put the clip back up to the stock position and it was still reddish coloring but i noticed the white. i think there might be an air leak or something.

suggestions?
 
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#7
if he was drawing oil in from the crankcase, he would be oil fouling his plugs. They would not be looking redish. redish colour plugs mean that the bike is running too cold.

what type of riding do you do? a 9 heat range is recommended in manuals becase the manual is built around the idea that your yz is under racing conditions and a 9 plug is needed for that. But if your just doing trails and occasionaly hitting the tracks use the 8 heat range, its more adaptable with a few tweeks of the carb.

My advice would be to put the 8 heat range plug in and see how it runs from there and see if you need to re-jet your bike. keeping in mind that you should be using a new spark plug when you diagnose the heat range of your engine.
 

Rich Rohrich

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#9
What's in the fuel you are running? Some metallic additives will leave reddish brown deposits behind.

The additive MMT which is used in a lot of OTC octane boosters will look like this.
 

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#10
im running premium 93 octane fuel, i have no clue whats in it. i will take a picture next time i get my hands on a camera.

how do you get the thread part off of the spark plug Rich?
 
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#11
take a hax saw and cut around the bottom thread untill your all the way through all the way arond and then just take it off.
 

Rich Rohrich

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#12
sixds said:
how do you get the thread part off of the spark plug Rich?
I cut it off on a lathe.
 
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#14
how involved is changing the right hand crank seal? i have one from a pack of moose gaskets but i want to know what im in for before i tear into the bike.