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Offline cb650 bobber

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one spark plug stuck
« on: September 04, 2007, 01:47:36 PM »
changed 3 of the four spark plugs last one wont budge....anything I could use or any tips has anyone ran into this before.
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Offline greenjeans

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Re: one spark plug stuck
« Reply #1 on: September 04, 2007, 02:10:46 PM »
got this off the tips section and it worked for me....

acetone mixed with ATF fluid.  soaked it for a day or so, heated the block with a heat gun and it cam right out.... Even worked on the stuck piston.   I had originally tried WD-40, PB Blaster and other stuff to no avail.
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Offline mattcb350f

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Re: one spark plug stuck
« Reply #2 on: September 04, 2007, 02:18:31 PM »
Greenjeans idea sounds the best, but I've had good luck with PB Blaster. but even with PB I had to let it soak for one or two days.
(http://www.blasterchemical.com/store/moreinfo.cfm?Product_ID=1)

 Matt.
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Offline Rsnip988

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Re: one spark plug stuck
« Reply #3 on: September 04, 2007, 02:21:22 PM »
will marvel mystery oil not work if you let it soak in?

RKS
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Offline mattcb350f

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Re: one spark plug stuck
« Reply #4 on: September 04, 2007, 02:24:34 PM »
never tried marvel myself, but I know PB Blaster puts all other penatrators to shame.  :)
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1974 CB350F,  1980 CB125S,  1981 XL80S
Non Honda's: 86 & 87 Husqvarna 400wr's

My CB350F resto: http://forums.sohc4.net/index.php?topic=30467.0
Gallery at:
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Offline mcpuffett

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Re: one spark plug stuck
« Reply #5 on: September 04, 2007, 02:25:17 PM »
Does the bike run? if yes try getting the engine warm/hot and try again it may work? cheers mick.
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johnny-from-bel

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Re: one spark plug stuck
« Reply #6 on: September 04, 2007, 02:49:53 PM »
Pneumatic impact wrench + wd40+ heat+patience. I have gotten everything lose and havn't stript a bolt since I have the PIW.

I case you do not have one. Use WD40 or any of the products mentioned above and a crate of beer. Apply heat. Put the wrench on the plug. Apply some torque not much. Then gently tap the top of the plug. Stop after a few minutes let it cool down. Here is where you have a beer. Repeat the procedure  (WD40 +Heat+ torque+tap) until you run out of beer. Try again the next day


Be patient it may (will) take a few days before it will budge.
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Offline BobbyR

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Re: one spark plug stuck
« Reply #7 on: September 04, 2007, 07:15:11 PM »
The acetone/atf works the best and I would use it first, then follow up with PB or whatever you want and let it sit. Haste makes helicoil!
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Offline Bodain

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Re: one spark plug stuck
« Reply #8 on: September 04, 2007, 07:39:25 PM »
My horror story... My current 78 F project had a broken spark plug stuck in one cylinder. I really had no experience with this. Just never had to deal with it. Anyway I went after it.  The plug itself was broken off. The threads is all that remained in the cylinder.

I first tried to jam a screw driver in it and turn. Quickly I discovered this was not going to get it. I went to the local hardware store to buy an easy out. First I applied liberal amounts of WD-40... Then applied heat with a torch... Lightly hammered the easy out in. Then used a small wrench to try and turn it out. It wouldn't budge!
This is where I make the bad decision... I decide I need more leverage. So I put an 18 in. pipe on it and I immediately snapped the easy out. The problem is. Now the hardened steel was broken off inside the spark plug threads.  Much hammering and I can't remove the hardened steel..   I'm hosed!!!!

Well I took it to work. We have a machine shop. They used an EDM machine to cut out the hardened steel. So I'm back with the head with the original spark plug threads stuck in the head... I now make a good decision. I decide to measure the inside thread diameter of a sparkplug hole and select a drill bit about .020 smaller. I drill right down the middle of that puppy and then pick the threads out. It's all looking good until I make another bad decision. I decide to remove the intake spigots for no other reason than to clean them up...  The spigot breaks..... Geesss...

That head is now in the trash...

Good luck?
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tbone

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Re: one spark plug stuck
« Reply #9 on: September 04, 2007, 08:03:01 PM »
Do Not Use a Pneumatic Impact Wrench!

Snap off the hex section of the plug and you've just added to your problem.

Plenty of oil, heat and a whole lot of patience. Gentile pressure, if it moves go back and forth extending the travel a little with each change in direction.

Once it's finally out spend a few bucks on a thread chaser before installing another plug. 
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johnny-from-bel

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Re: one spark plug stuck
« Reply #10 on: September 04, 2007, 10:20:12 PM »
Quote from: tbone on September 04, 2007, 08:03:01 PM
Do Not Use a Pneumatic Impact Wrench!

Snap off the hex section of the plug and you've just added to your problem.


I beg to differ. The torque on the impact wrench is so low (in fact you can hold it still by pinchin it with two fingers) it will never snap off the hex section. It is the constant hammering that does the work.
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tbone

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Re: one spark plug stuck
« Reply #11 on: September 05, 2007, 03:01:09 AM »
Quote from: johnny-from-bel on September 04, 2007, 10:20:12 PM

I beg to differ. The torque on the impact wrench is so low (in fact you can hold it still by pinchin it with two fingers) it will never snap off the hex section. It is the constant hammering that does the work.

And some pneumatic impact wrenches have sufficient torque to snap a rear axle on a CB750!


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johnny-from-bel

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Re: one spark plug stuck
« Reply #12 on: September 05, 2007, 04:28:33 AM »
Quote from: tbone on September 05, 2007, 03:01:09 AM
Quote from: johnny-from-bel on September 04, 2007, 10:20:12 PM

I beg to differ. The torque on the impact wrench is so low (in fact you can hold it still by pinchin it with two fingers) it will never snap off the hex section. It is the constant hammering that does the work.

And some pneumatic impact wrenches have sufficient torque to snap a rear axle on a CB750!




Suffice to use one like I have with adjustable torque
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