HOW2: Remove & Refit Spark Plugs

[SnowTigeress]

"THAT'S SO SIMPLE!" you say. WHY do you need a Photo-How to for unscrewing a spark plug?!?!"

That's what I thought; & even TEF, who will never give the 'short' version if a 10,000 word essay will suffice, didn't think it was THAT worth mentioning.... BUT, after answering the FAQ "Stripped Spark Plug Hole, What's a Helicoil' umpety hundred times...... he thought it MIGHT actually warrant a mention! Prevention is better than a cure, after all! So!

EXCESSIVE FORCE IS NOT REQUIRED

Socket Sets are your ENEMY! Far to easy to apply far too much force. But, often only tool in the box that will fit a motorbike spark-plug, and burried deep in a casting with double overhead camshafts either side it can sometimes be awkward and the extensions & knuckle joints, can be useful, but be warned, more between your finger tips and spark plug, less 'feel' you have to avoid over tightening or cross threading.

https://s1177.photobucket.com/albums/x349/snowtigeress/engine/imag2532.jpg

Keep the socket as square to the spark plug as possible. Let the socket 'fall' over the plug, grip the wratchet 'losely', and apply a gentle even pressure to the end to start it turning, and hold the centre of the socket over the centre of the spark-plug.

https://s1177.photobucket.com/albums/x349/snowtigeress/engine/imag2533.jpg

As soon as the initial pressure is taken off the plug, STOP using the leverage of the wratchet. Remove it and if you have to use the socket or extension, twist it like a screwdriver, with 'finger force' only, until you feel the plug starting to 'wobble' in its threads.

https://s1177.photobucket.com/albums/x349/snowtigeress/engine/imag2535.jpg

THEN wind the last way out, wherever possible PURELY with your fingers.

Refitting plugs is pretty much the reverse.

https://s1177.photobucket.com/albums/x349/snowtigeress/engine/imag2571.jpg

Putting the plug in; START the plug VERY gently. Avoid just 'dropping' the plug down the spark plug rebate. You do NOT want the electrode on the bottom holding the critical 'electrode gap' to get bashed on the cylinder head and closed up. Engine wont run well if it does. So try and lower it in, preferably with your fingers, and get it central in the hole, before you get metal trouching metal.

https://s1177.photobucket.com/albums/x349/snowtigeress/engine/imag2572.jpg

THEN, again, with your fingers, GENTLY get the spark plug square and twisting into the threads, without cross threading. This high up the hole the plug can 'wobble' a bit, so dont force it, tickle it into the threads.

https://s1177.photobucket.com/albums/x349/snowtigeress/engine/imag2574.jpg

As removal, if you need to use socket and or extension like a screw driver to wind the plug to the bottom of the hole. ONLY when it has bottomed out, do you need to use the wratchet, and THEN only with finger force to just 'nip' the sealing ring between the plug and head.

Again, cradling the wratchet to keep it central over the plug, and using 'just' finger tip pressure on the handle to apply that 'nip'.

Be careful of your spark-plugs and gentle inthier handling, and your cylinder head will thank you by NOT stripping its thread.

If you are clumsy, brutal or lazy, with them? Well, then the liklihood is you will suffer a cross or stripped thread.

If you do, and you are lucky, the thread may merely be cross threaded, and a 'cleaner die' might be used to reform the damaged threads.

If not, then it will proibably require helicoiling; which is a process of drilling out the damaged thread, and cutting a new larger one, the same pitch, and winding in a coil of metal wire to sleeve the thread back to the spark plug size.

If you are very lucky, then this might not need the engine removed from the bike, or necesserily the engine stripping so that the cylinder head can be drilled. But dont bank on it!

And once helicoiled; make the same mistake again, and you can strip the insert AND thread in the cylinder head, and do THAT, and chances are there is probably no cheap or easy fix!

So, prevention is better than the cure, and ALL it takes is a little care and attension.
____________________
Real bikers build their own Renovated and Riding a 1986 Honda CB125TD-C called the Pup. Full Licence 13/09/2012, 1994 Moto Guzzi 750 Strada
Can-Do Girl that does spanners TOO!
TheSmiler: binning it is better than going around a roundabout the wrong way

[stinkwheel]

Just to quantify that "nip". From finger tight, referr to the following chart for how many degrees to turn the sparkplug when it's a new one out of the box.

Note that if you're refitting an old one, the manufacturers recomment tightening it 1/12 of a turn from finger tight.

https://www.bikechatforums.com/download.php?id=82949
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[dodgydog]

Various pieces of rubber pipe, (fuel pipe and the like) can be useful to slip over the end of the spark plug. Very handy for deeply recessed plugs. It gives you much more feel when getting the first few threads turned in.
I have some pieces of pipe made up, with some thin wooden dowel inside the top part of the tube for stiffness.


Dog
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I know that you believe that you understood what you think I said, but I am not sure you realise that what you heard is not exactly what I meant

[bikenut]

hi dudes,

once slack remove and refit by hand. rubber pipe slide onto plug may ( will ) help for plugs buried deep down plug holes.

lub plug thread before and during reffiting but dont bridge the gap with copperlube.

as a matter of interest the bike in the pics ( cb125t ), once the plugs are slack and removable by hand, DO SO as socket will foul on casing and cause thread ( 10,mm plugs from memory ) to STRIP!

[Blau Zedong]

This thread is beyond retarded. Are we really at the point of discussing how to change the plugs on a naked 125?

Fair enough if it was some exotic faired 400 or 250 IL4 which requires a tame 4 year old's fingers just to get the ratchet in.

Right I'm off to fucking kill meyself.
____________________
18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[TheSmiler]

[lihp]

For those "nip" etc, and something easy to strip, it's why a torque wrench is absolutely essential

[neil.]

Yep I always use torque wrench on plugs, and a smear of copper grease on the threads before fitting - makes a very good earth connection and aids future removal.

Also worth mentioning using an old paint brush or something similar, maybe with a squirt of compressed air, to clear any crap around the hole so it doesn't fall into the combustion chamber before removing the plug in the first place.
____________________
CBT February 2008 | A2 June 2008 | Yamaha YBR125 (written off) | Honda CBF125 (current)

[swampy]

[SnowTigeress]

[Drake]

just no
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was: derbi senda, aprilia sx125, nsr250 mc16, cagiva mito, cb600 hornet now: mk1 bandit, KR1S, landrover series 3 light weight 2.5 petrol, 5speed box

[lihp]

I have a set of 3 torque wrenches in differing ranges, which is useful.

Swampy, For almost all bike maintenance, I would say that torque wrenches are essential, and worth investing in and learning how to use.

There are a lot of aluminium threads on motorcycles, and threads are easily damaged on these soft metals.

Spark Plugs, Sump Plug, Oil Filters, Sprocket Nut, Axles, sprocket carriers, brake disc bolts.

That's just general maintenance, they're even more important if you want to start replacing engine gaskets, or doing serious repairs.

[Teflon-Mike]

[swampy]

[Poseidon]

If you want to do a how2 on spark plugs, you'd do well to do one on how to remove the plug from the middle cylinder on a triumph T300 series bike without having to remove engine covers, or indeed the engine itself...

https://www.worldoftriumph.com/tpl/images/304401.jpg

See how the frame covers the hole perfectly with very little clearance underneath, coupled with narrow plug holes that are too narrow for standard spark-plug sockets.
____________________
1977 Honda CG125
2002 Ducati Monster S4 (currently restoring)

[st3v3]

[bikenut]

hi dudes,

if your a beginer and taking the plugs out of a cb125t with the sockets you have it is possible ( more like probable ) to strip the thread as the socket will more than likely foul the head resulting in a stripped thread, the beginer will probably not realise this is happening but happens just the same, so, once slack, remove by hand or use pipe.

always ( always ) start the plug in and turn by hand, as cross thread will be evedent ( and SOFT ), rather than by socket and bar with reduced FEEL.

be made aware........there your threads...........and expensive to fix.

[Teflon-Mike]

[bikenut]

hi mike,

m of m and c did it with a half inch drive, they ruined the thread as socket fouled head....

i had warned them of this as it happened to me ( realised before any thread buggering issues ) some ions ago........

it can happen on this bike.....

anywho, would you look at the pics about the cam chain valve clearance adjust string, i think the left exhaust spring may be upside down, some better pics and your opinion ( as you are god on here for tigress 's piece of mind and engine....

[st3v3]

[bikenut]

:karma: i blame my long hair, whats your opinion about tigress valve springs

[Teflon-Mike]

[bikenut]

hi mike,

sods law, if it can happen it will, and did........

whats your opinion of valve springs being upside down, in fact can they be fitted up side down, are they meant to be fitted a particular way.........

i have read tappet adjust string and reacted to the photos.........

respectfully yours.......

[Bomberman]

[stinkwheel]