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HELP!! Broke my "05 spark plug off in head !

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$*&T !!!!!!

Need advice quick as I have a race in 7 days and just had a major screw up and need to see my chances of pulling the head and fixing quickly.. There are no dealers nearby.

I need advice from someone who has pulled the head on this bike before.

The Story:

I have a 2005 yz250f. It's new to me so I am going thru it piece by piece and doing maintenance. I have done everything except the plug. I went to change the plug today.

The plug was not was not budging with a 3/8 ratchet on it..... My buddy suggested a "Breaker Bar " and it worked really freaking good .....It broke the frozen plug at the threads. IM SO STUPID TO LET THIS HAPPEN !

The broken top half of the plug when i got it out with magnet revealed a bunch of rust and corrosion down there. The small plug drain hole was clean, but i suspect water got in there from cleaning etc and sat in the thread seat. Im assuming PO has not changed the plug in quite a while. Funny cause everything else on the bike looks really well maintained.

I like where there are no shops within 3 hours. I have tons of tools and have worked on cars, sterndrives ,outboards, bikes. I have never gone into a 4 stroke Thumper.

I have no manual at this time. (I'm looking for one now)

Any advice on how to attack this and get to those threads to try to coax them out ?????

I want to wrap my head around what I need to do to fix this asap. WHat is it gonna take to remove the head to get at the threads ????

What do I need to watch out for ?

Do I need specialty tools ?

Steve in Florida

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They usually will come out if you can get something down there to just turn it out, It probably will not need any if much power on the part to remove it. Put some lube down there and try an ez-out. If that doesnt work you will have to remove the head.

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damn! thats rough! if your good with a drill you could drill out the remaining part of the spark plug with a bit just smaller than the threads (this is what i did for broken bolts on cars) but for a sparkplug it seems a little more risky, or you could drill alot smaller, then use a tap to make threads on the drilled out spark plug, red locktite a bolt onto the drilled out sparkplug, then use some "open-shut" and hope for the best ?

hope you figure it out!

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I would shoot a good amount of PB Blaster in that spark plug hole immediately so that when you get a chance to remove the head the remainder of the spark plug will hopefully come out more easily.

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Thanks for replies so far, especially that manual !

I went back to the bike after posting and shot corrosion x in the spark plug hole, enough to flush it, then I plugged the drain hole and filled chamber so it can sit / soak.

I also unhooked the carb, header, mounts. The water is drained .

I am still sooo pissed that we just did this to my yammi as the bike ran soooo well !!!!!

I'm worried it will never be the same after I go into the head, cams etc.

My worry is certainly because I have a lack of knowledge of how hard it is to get a head off and on without screwing anything up.

But there is no choice. Those threads were stuck bad. I will be very very

Lucky to drive/ drill them out from the bottom once the head is off.

Next time, and for all of you out there... Never ever ever force a plug to come out!

I should have looked with a light, mirror, saw the corrosion way down there, and sprayed corrosion breaker in there and walk away for 24 hrs. I should have come back with a 3/8 impact ands slowly tried to move it.

So has anyone taken this head off/ on without doing a whole

Rebuild ?????

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Link To manual not working.... Anyone have another ?

I will gladly buy one. What is the best manual for the yz250f ?

1) Go here: http://www.yamaha-motor.com.au/

2) Click on "Support" at the bottom of the page

3) Click on "Owners Handbook" on left side of the page

4) Fill in the fields with your bike's information, then click "Search"

5) Download appropriate manual (if you don't have Adobe Reader you'll have to download that too)

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Do not attempt this project without the proper torque wrench. You need a light duty one that goes as low as about 25 in-lb (1/4" or 3/8" drive). Something like this: http://www.sears.com/craftsman-microtork-reg-torque-wrench-25-250-in-lbs-3-8-in/p-00944593000P

I would also check the valve lash before disassembling the engine. You will need a feeler gauge set that has blades that are very thin. Many sets start at .005", which is too thick. I used this one and found it to be perfect for the yz250f: http://www.rockymountainatvmc.com/productDetail.do?navType=type&webTypeId=140&navTitle=Tools%2FShop&webCatId=22&keyword=feeler&prodFamilyId=20116

For what it's worth, when I pulled the spark plug on a new to me 250f I was surprised how much corrosion was on it. The plug cap/coil did not seal well. I put grease on it when I reinstalled it hoping it will seal better.

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Thanks jet rep,dr Da da.

I am assembling a parts list for this: So far :

Yamaha manual

inch pound torque wrench ( craftsman)

Feelers

Shims ?

Head gasket

Should I change my cam chain while in there???

Since this spark plug was so cruddy, I wonder what other maintenance was undone.

Time to check it all. Kind of brutal experience after only 2 rides with this bike.

Motor is stripped, need To drain oil, remove valve cover and get all the way to the head to drive the threads back out somehow. I may try to easy out from the top once head is in my hands.

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ouch, you should have sprayed some pb blaster in it first, then taken the wrench and hammer and tap on it a bit to loosen things up, not start wrenching on it. take the head off and spray some more pb on it.

an inch pound torque wrench is always a good thing so yoyu dont overtighten things or strip them, an owners manuel is always a must when working on bikes. you could replace the cam chain if you wanted to, it all depends what shape its in, i would also invest in a new head gasket also, just make sure your thorough when going through it all, and make sure its all correct, good luck

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Thanks for the helpful comments. Anti seize and PB blaster .... Ahh if only the PO did these things I would not have seized plug threads.

Anyway, full top end gasket set is ordered and I am meeting a mechanic at the race this weekend and we are going to get into it there in his portable shop. If all goes well we will bang it out in a day and have a look at the cam and valve specs while we are in there.

If all goes well I'll be racing it Sunday.

We will see.

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Thanks for the helpful comments. Anti seize and PB blaster .... Ahh if only the PO did these things I would not have seized plug threads.

Anyway, full top end gasket set is ordered and I am meeting a mechanic at the race this weekend and we are going to get into it there in his portable shop. If all goes well we will bang it out in a day and have a look at the cam and valve specs while we are in there.

If all goes well I'll be racing it Sunday.

We will see.

good luck man! in the future dont start wrenching on things that wont budge, youll jsut break something and make a bigger mess, now you know :lol:

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I had this happen on a old 2 stroke. I sprayed the threads with PB and used an easy out. The thing was a pain but it still came out.

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Pb blaster seems to work better than wd-40 for sure. I had seem corrosion

X ( super expensive) do some amazing things to corrosion on my outboard

Motors. Completely stops it and seems to prevent it from coming back.

I don't know if it penetrates like PB however, so I may do PB next.

Yea, never ever force a spark plug. The threads are hollow and

Very very thin. I have anti seize compond and will coat the new plug for

Sure.

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OK, I am out of the woods. Here's the fix with pix for others in the future.

Bartow2011steve-1-M.jpg

RECAP: Had the bike for a few weeks. Ran fantastic. I was doing routine spark plug replacement on the bike so I can start fresh with everything and get on my own maint schedule.

The plug was frozen, not removable with 3/8 socket wrench. MY buddy took out a breakerbar and it broke off at the threads. PLug broke pretty easily. IT was an NKG cr8eix /iridium.

IMG4394-M.jpg

I shot corrosion x then PB blaster in cylinder hole and plugged the drain hole to keep it in there.

I got a manual, ordered gaskets, looked at a bunch of YOUTUBE videos and then removed the head once i studied the procedure many many times. Removed the porcelain, removed electrode.

This plug looks ok from the bottom...trust me, it is frozen solid in there and the head is busted so there is no way to turn it.

IMG4432-M.jpg

I tried easy out and chisel from the plug boot side. Gently tapped, tried to turn the threads out. I worked for 2 days with the head in my hands, easy access to both sides. I drilled the threads out very carefully with 2 drill bits, careful not to go too big and start taking head threads with the drill.

I removed as much of the soft spark plug threads as possible, Real easy to drill. No matter what i did, the threads were still stuck. I read over and over that you need to be patient and go slow, keep soaking in PB blaster. Thats what I did. The threads that were left were still stuck after 4 hrs of wrenching and tapping over the weekend. I even froze the removal tools overnight hoping to shrink the threads. Be careful as this may make a cheap easy out break even faster. I never used heat. Too afraid to warp the head or melt the valve guides.

IMG4437-L.jpg

This is not what you ever want to have to deal with...trust me.

IMG4441-M.jpg

Even with just a bit of threads left, the plug wouldnt budge. I gave up and was going to send it to a machine shop. :lol:

I was thinking about it and I decided to try one more thing. Instead of attacking it myself, I got a couple friends. I had one of them turn a square easy out from the cylinder side of the hole, I turned with a chisel from the plug hole side, another buddy helped hold head on the bench sideways. (We had no Vice)

More PB blaster.... Then, the thread on my side started to turn. Very slow,hard, but smoothly. UNBELIEVEABLE. Almost 1/2 inch of threads came out.

Here are the first threads removed by the squared off chisel tool i had laying around. IT turned out to be a perfect tool, very hard, thick, sharp edges and a slow taper. It fit nice in the drilled out plughole. I think its key to have the right type of removal tools for this.

IMG4463-L.jpg

It took another 45 min of struggling to get the other 1/2 " or so of the threads out. They were a little buggered so I drove them out through the cylinder side. I used a square easy out. It squeeked and fought the whole way.

IMG4464-M.jpg

The threads were so stuck, I couldnt believe they came out and left decent threads in the head. But here it is. Needs a bit of thread chasing but it's almost ready to have the new plug installed.

THe funny thing was it almost looked like there was in fact some neverseize on the threads. In any case, I will always use antiseize lube on these threads. ******EDIT***** I have added info below about anti seize that I discovered after I wrote this post. It's possible looking at all the evidence that this was actually caused by anti seize on the plug******

The yz250 plug is unique and delicate. It sinks way into the head with 3/4 inches of 10mm dia SUPERFINE 1mm pitch thread. The plug threads are 19mm long. Thats alot of thread.

I suspect the plug was in there for 2 years or so, and that water got in though the drainhole during washing /riding and was never blown out. There was maybe nothing on the threads to stop corrosion either. Either way, looking at this now, it is SUPER IMPORTANT to check, change, lube the threads on this bike, and probably many other small thumpers.

IMG4466-L.jpg

Tomorrow i go to a motorcycle shop and have them clean up the 1mm pitch threads with a tap. I cant find a super fine 1mm pitch tap for sale anywhere near me.

Now I got to look at getting this all back together and am going to check the valve clearance before i button it up. :)

Edited by gunforhire

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Glad you got it out! The only thing worse is a small, broken off tap, ask me how I know:foul::lol:

Looks like you did it right without going ape and destroying anything. Good job!

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If you read my post carefully it sounds like I plan to use anti seize

On the plug in the future. Now I'm not so sure. The funny thing is, as hard as these threads

Were to remove, it looks like they had anti seize on them once

I got them out ! ***

Well, i was talking to a factory thumper mechanic tonite who said to

Never use anti seize when you have dissimilar metals + heat, water.

With thumpers: Plug is steel, head is aluminum. Antiseize Introduces even more metals To the equation. Lots of Potential for galvanic corrosion.

If u look at the threads on my head, you can see they are pitted, but there was

No rust. Hmm .... Were they actually corroded and stuck because of the

Antiseize?

Maybe what looks like anti seize is just the effect of the pb blaster

Mixed with the grinding of the threads coming out , making tiny bits of steel mixed with corrosion spray....

The reason I don't know is because I am not the one who put the plug in. The PO did it.

This needs to be looked at. When to use anti seize and when not.

Edited by gunforhire

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