Spark plug failure question

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virginian

virginian

New Member
Dec 19, 2009
117
0
0
McLean VA
I started to have trouble stating my engine. It is a Tanaka 32 with 2500 miles, and it would usually start on the first try. But several times in a row it took many tries and then did not start at all,

I replaced the spark plug and it then started just fine. Should a spark plug fail after only 2500 miles?

Its appearance was a light brown/rust like color. No oil on it.

However, with the new plug I lost 2 mph in speed and the engine was louder. Is that normal?

After about 200 miles, I have regained 1 mph and the engine has quieted down. Is that normal for breaking in a new plug?
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
A plug can be bad right out of the box or it can last 50k miles plus.
As for breaking in a plug, they do not need to be broken in at all.
What do you have it gapped to?
 
Goat Herder

Goat Herder

Gutter Rider
Apr 28, 2008
6,237
20
38
N.M.
As a practiced Auto Mechanic. I tell all plugs new the gap should be checked. While its true to some degree they may be gaped right. It is always good to check.
 
GearNut

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
I have very rarely found a spark plug properly gaped right out of the box.
The factories just assemble them and leave gap adjustment to the installer. Not all engines have the same requirements so the gap needs to be set to the particular engine's requirements.
Set your plug gap to .024 - .028".
 
Dan

Dan

Staff
May 25, 2008
12,765
115
48
59
Moosylvania
LOL, had a heck of a time with a HF. It ran fine but stuttered and chugged starting off. I had beaten on the clutch trying to make it fail so assumed it was that. Also didn't have peddles. Turned out it was just the gap. I'm supposed to know better but seldom do. Gap, 4 minutes of labor. Clutch 1 hr of labor and 63 bucks
 
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