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LengerichKA88

K181: RJ8C /J8C spark plugs

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LengerichKA88

So, I’ll start by saying that my mechanical knowledge is limited, but I do know more than nothing. 

 

I have a tractor (model hasn’t been narrowed down between Commando 800 or a No Name) with a K181. It’s new to me so I’ve been slowly going over it. 

The spark plug was filthy, so I figured I’d spend the two bucks to get a new one. Look at the manual and it calls for an RJ8C. I found a J8C that had “RJ8C” printed underneath. Figured that was the way to go and came home and put it in. Now it doesn’t want to start. It cranks and tries to fire, but what made me hop off and get on here was the massive back fire my last attempt at turning her over caused. I don’t wanna make more work for myself by screwing something else up. 

 

I sould also note, I have the air filter off at the moment, as the one that was in there was history, and was getting smashed into the intake. This is where I noticed a nice little jet of smoke as it popped. 

 

Should I be using a Champion J8C, or is there something else I should be getting? TIA

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WHNJ701

throw the champion out and buy an ngk plug 

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953 nut

The J8 is the important part of the plug number, the "C" means copper plated electrode and the "R" means it has a resistor built in to prevent radio interference. Did you gap the new plug at .035"? Was the engine running well with the old plug?  If so what was the brand and number on the old plug?

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cafoose

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ebinmaine

You'll find that spark plugs are a brand preference to a lot of us for the most part.

Having been in the auto parts industry in the past I can vouch that Champion has definitely had some serious issues back in the 1980s and 1990s.

They were combining as much as three heat ranges into one spark plug.

That meant that quite often two out of three people were not satisfied with what they got for two opposite reasons. That really stung on their reputation.

 

Supposedly, they revamped their line back about 20 or 25 years ago.

I had not touched a champion plug in at least 25 or 30 years until just a couple years ago. That was what was recommended by some of the guys online here and also a couple of small engine shops locally.

They've been running fine for me but I'm not sure they give the life expectancy that I would like to see from them.

 

I've never used an NGK but I've also heard very very little bad about them. I can see why people would use them in everything they have.

 

I've had excellent luck in the past with AC Delco and Autolite and Motorcraft.

 

Your j8c plug is the correct one.

The spark plug itself is not very likely to be the cause of your backfire.

 

You may need the carburetor to be cleaned out and refreshed.

Non-ethanol gas is the way to go. Unfortunately, most people don't use it. The ethanol is absolutely disgusting and much much worse for small engines.

 

If you haven't already done so, it would be a good idea to replace all of your fuel line and rebuild the carburetor.

 

There are definitely other things that would cause a backfire but I don't have enough knowledge of the internal engine workings to comment on them.

 

 

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LengerichKA88

Thanks everyone!

 

  It was running on the old one, and the old one was a RJ8C, but I don’t know how long it’s been I’m there, so I figured I’d replace it. It’s gapped at .025, which is what I read in the manual, should I re gap it to .035?

I have the fuel lines, just haven’t had the chance to throw them on yet, but that’ll move up my list. 

 

It hasn’t backfired since, so I may have been overly cautious, but like I said, I didn’t want to make more work for myself and run the risk of screwing something up. 

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diesel cowboy

If it was running fine with the old plug it kind of sounds like maybe its not firing all the time due to either the new plug being defective or needing new points/condensor and it allowed excess gas to build up in the intake and when it finally fired caused the backfire

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pfrederi

Correct gap on K181s with battery ignition is .025  (Big blocks 10hp and up are .035 )

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LengerichKA88
6 hours ago, diesel cowboy said:

If it was running fine with the old plug it kind of sounds like maybe its not firing all the time due to either the new plug being defective or needing new points/condensor and it allowed excess gas to build up in the intake and when it finally fired caused the backfire

 

could very well be. We've only had it since august , and I'm really just getting into it. We were told it was all original, so no telling what been done to it. The guy who had it sounded like hed not done more than put gas in it 

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LengerichKA88
6 hours ago, pfrederi said:

Correct gap on K181s with battery ignition is .025  (Big blocks 10hp and up are .035 )

I didnt know if it was an insider secret to put em at .035 instead haha

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953 nut

I have an older Kohler manual that calls for .035" for the K-181 but the one in our manuals section calls for .025" like Paul @pfrederi said. Can't imagine why as you have the same points, condenser and coil as the larger Kohler's.     :confusion-confused:     Glad to hear it is ruining well!       :woohoo:

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LengerichKA88

@953 nut I didn't know that, but I'm still new (wouldn't wanna say "green" around here I imagine haha). Good to know though

 

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953 nut
13 minutes ago, Lengerich8 said:

wouldn't wanna say "green" around here I imagine haha

:text-yeahthat:                     :ROTF:

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