Wednesday, December 4, 2013

Tuneup time - walkthough on changing plugs and oil on GSF1250 and GSX1250FA

I thought I would do an owner's description of a basic tuneup (plugs, oil and air filters) to help out those who want to give this a go.  A lot of manuals assume basic knowledge, but judging from on line questions on the forums, there's a need for basic advice.  Doing this yourself will save a lot of money.

This guide reflects my personal experience, so do it at your own risk - if in doubt, consult a mechanic. It is worth investing in a repair manual.

What you will need is:

- a good metric socket set, ideally with an extension drive to give more reach and one of those flexi connector enabling you to use it on an angle
- an oil drain tray capable of taking at least 3.5 litres and not so big it won't slide under the bike when on the main stand
- a long Phillips screwdriver (12 inches or so)
- a torque wrench capable of low range reading from around 10 - 25 nM (not essential but good to have)
- some rags
- set of vice grips, a small vice, hammer and small cold chisel to remove the crush washer off the drain plug
- oil (4 litres of 10W40 semi synthetic such as Castrol 4T or Golden Spectro)
- oil filter (OEM or after market)
- drain plug washer (recommend OEM but copper OK)
- air filter (or cleaning kit if you use K & N or BMC or similar washable one)
- spark plugs
- stainless steel measuring jug and funnel
- copper anti-seize grease 

I bought a new set of Iridium plugs off Ebay (at less than half the price I'd pay in NZ).  The type is NGK CR7EIX. The iridiums last longer than a standard plug and allegedly fire better, and I can get them for a similar price to standard plugs here.  I can't say I can detect any difference.  The standard plugs (NGK CR7E) work fine though. (You can also use Denso U22ESR-N).  The plugs are easy to replace, and I do this first while the engine is cold

1. Remove the tank and lower fairings if they are fitted.  To remove the tank, grab a rag and a 10 mm ratchet.  Remove the two bolts at the rear of the tank and wiggle it back an inch and lift the rear.  On the right rear are two rubber vent/overflow hoses that press fit onto spigots on the tank.  They just pull off, but can be a bit sticky.  I pull the tank back a bit more and hug it and remove the electrical connector on the right middle by depressing the tab.  This can be sticky, so a smear of electrical grease makes subsequent remove easier.  I slide a rag underneath the fuel outlet, then depress both blue tags with my left hand while pushing with my right thumb against the lip of the connector.  It will pop off the end of the pipe.  (This is why I hug the tank and it's not misguided mechanical intimacy). Reinstallation is just the reverse.  Make sure the fuel connector goes on with a positive 'click' as it is pressurised and you don't want it popping off with the bike running.   If you miss the electrical connector the bike won't start.
2. Use the smaller of the two spark plug wrenches in the bike's tool kit plus the 14 mm spanner
3. Start on the left hand side (in fact either side), and unclip the connector from the coil stick by depressing the small tongue on it and wiggling it back.
4. Rotate the coil back and forwards a little.  I use a long screwdriver to gently lever under the coil top to pop it free of the plug.  Don't use too much force.  
5. Slide the coil stick up and wiggle it past the cutout in the frame tube to let it free.  If you have compressed air, blow in the plug well before removing the plug to remove any grit before removing the plug.
6. Push the plug wrench down onto the plug and use the 14mm spanner to undo it.
7. Take the NGK plug, remove the screw on cap, put a smear of copper grease on the threads (not essential but helps stop threads seizing) and screw it in.  Do this by seating it firmly in the plug spanner (the rubber grommet holds it in place), and screw it in gently first by hand, being careful not to cross thread the plug.  Be careful not to over tighten.  11 Nm if you have a torque wrench that fits, or use the spanner but hold it near the head so you don't lever on it. Don't try and gap the iridiums - they are factory set
8. Check that the coil stick is clean and free of corrosion (I often use CRC silicone spray to clean it) and put it back onto the plug and give it a firm push and a wiggle.  They usually click down after a good firm push.  Make sure it's well seated.

I usually go to the other side of the bike and do the other outer plug the same way.

I then get a 10mm socket and undo the 4 bolts holding the thermostat to the frame so you can wiggle it out of the way.  I use a 14mm socket on a flexible adaptor on an extension bar to allow me to use a ratchet to remove the middle 2 plugs. You can use the spanner but it takes ages and is fiddly.  The process is the same for the other plugs and I use the smaller of the two plug wrenches this way.  Don't forget to replace the thermostat bracket before you replace the tank!

While the tank is off, I check and clean (or replace) the air filter and make sure everything is clean. There are 4 screws on the filer cover, one at each corner of the box.  Whoever designed it needs a beating.  I suggest removing both side covers and accessing the bottom-most screws and put some tape on the sides of the air filter box where the captive nuts live.  If you don't, at some point the nut will get flicked out while you are trying to replace the cover and disappear somewhere, never to be seen again.  (Don't ask me how I know). Rather inconveniently, Suzuki don't sell them and they are an odd shape to fit the cutouts on the filter box. Buy yourself a long Phillips screwdriver to reach them, and take it from me, spending a little time to tape them in place will save a lot of swearing!

I then start the bike and make sure it is running properly.  If you have the gear, that is the time to check the TPS and throttle body balance (search the blog for instructions).

I let the bike warm up and while doing so, check the coolant level at the reservoir (make sure the cap is fully seated afterwards), and the throttle free play.  I use a good linkage lubricant (don't use WD40) on any pivot points and give everything a once over (chain tension and condition, brake pads, fastener toghtness etc). 

Once the bike is warm, I change the oil.  I use the OEM filter and bought a cheap filter removal tool that pushes onto the end.  K and N also make a good replacement (KN138 or a Hi-Flo HF138) with a handy nut on it.  Put some cardboard or newspaper under the bike and put a drain tray under it.  I turn off the bike and use a 17 mm socket to remove the drain plug.  Use disposable gloves as the oil is hot and used oil is carcinogenic.  Undo the plug and remove it and let the oil drain.  Remove the fill plug and wait until it's all cleared out, then get some tin foil and fold it under the filter and shape it so it funnels oil that flows out from the filter base into the drain tray.  It stops oil flowing over your headers and stinking when you start the bike.  Undo the filter until oil is flowing onto the tin-foil and let it drain.

Once the bulk of the oil stops flowing, undo the filter further and remove it from the left hand side by pulling the radiator hose out of the way (nothing needs to be removed).  Mechanics gloves help as the headers are hot.  Give the filter base on the engine a wipe, smear some oil onto the new filter O ring and reinstall.  Tighten it until it's snug and turn it about another turn (don't try the 2 full turns as the manual says as you will overtighten).  It doesn't need to be cranked up, fully hand tight plus a bit is sufficient!

Check the drain plug.  There shouldn't be chunks in there of metal or fibre.  You should replace the drain plug washer.  The OEM one is a crush washer and I use these (you can also use a copper washer).  The manual is silent on removing the thing and I am convinced that the person who designed this also designed the air filter screw location.

To remove the washer, I put the head of the drain plug in a vice (not the threads) and use a small cold chisel and tap gently on each side of it between the bolt and the washer, to fold the edges up gently.  I then use vice grips to grab the folded up edges and then unscrew it up the threads.  It's easier than trying to cut it off, and unscrews nicely. Be careful when you first do this as the old washer crushes on well and it looks like it's part of the bolt.  You can likely get away with re-using it but it's not recommended.

Replace the drain bolt, being careful not to cross thread, and I really recommend using a small torque wrench (22 Nm) as people have been known to crack the sump through overtightening.

With filter, you will need 3.5 litres of 10W40 oil.  Add about 3.2 litres first, (make sure the drain plug and filter are in place or you will make a huge mess) and replace the fill plug and start the bike and idle it until the oil light goes out.  Go and have a coffee and then inspect the oil level with bike on the main stand.  I find 3.5 litres takes it to full.  It is really easy to over fill if you don't wait for the oil to slowly drain back into the clutch cover.  You won't need more than 3.5 litres.

Changing the plugs takes less than an hour and oil about half an hour once you have done it once or twice.  Take your time, don't overtighten and if a friend who knows their way can help out, so much the better.


  1. Thank you. Very helpful, informative and hilarious. Keep up the good work, buddy!

  2. Hi my friend I have the same motorcycle and I am having a problem removing the front cowl which also covers the headlights. I cant seem to remove the speedo and tach meter that does not seem to want to come out.. I must remove that in order to remove the screws which secures the front cowl correct?

  3. Remove the two screws on the lower edge of the instrument panel. Put a towel over the top yoke and cable guides to protect things. Wiggle the lower edge of the instrument cover with one hand and pull down and towards you from the top. There's locating lugs at the top edges. It's harder to describe than do

    1. Thank you friend. I will try this..when weather gets warmer here in NYC. :)