We answer some typical questions from the Suzuki faithful...
Suzuki dirtbikes – YELLOW questions
1. Timing Plugs
I am trying to remove the timing plus from my RM-Z engine so I can set my cam timing but the timing plugs are so tight that they are starting to strip the centre out of the plugs. Why are they so tight and how do I get them out?
Because the timing plugs are an alloy plug screwed into an alloy cover they become quite tight due to heat, vibration and dirt built-up in the threads. To loosen them give them a slight tap with a steel hammer to loosen them before undoing them. Be careful not to hit the plugs so hard that they crack but firm enough to jolt them loose.
2. Sump Plugs
I have drained the oil out of my RM-Z but I only got about 500mm in the drain tray. When I refilled it with the current amount of oil I noticed fluid coming out of the breather nose. I checked the oil level and it was way too high. Have I got all the oil out and, if not, what have I done wrong?
There are two sump plugs on the RM-Z. One is at the rear of the engine and the other is towards the front, underside of the engine. On the later-model RM-Zs it is a 12mm bolt but on earlier models it was a 5mm Allen-head that screwed into the case underneath the stator cover. To get all the oil out of these engines you also will need to remove a timing plug or the oil will vacuum lock and not run out of the sump plug. There is an oil screen that should be removed, cleaned and refitted at each oil change.
3. Fuel-line Coupling
The fuel-line connector on my RM-Z is very tight, and difficult to undo. I’m always worried about breaking it when I remove the tank. Is there some kind of trick to disconnecting the fuel-line coupler?
These couplers always become tight due to water and dirt. Before trying to disconnect the coupler, give it a good spray with WD40 then blow it off with compressed air. Then, while holding pressure against the coupler in the direction o the fuel pump, squeeze the two tabs together and slide them backwards. Once those tabs are released, pull the coupler off. Before refitting, give it another soaking in WD40 and it will slip back on nicely.
4. Idle Speed
My fuel-injected RM-Z always stalls at low speeds, either in tight turns or ruts. It seems to idle really slowly. Do I need to take it back to the dealer to get the idle adjusted on the diagnostic computer or can I do it myself somehow?
You can actually adjust the idle on your fuel-injected RM-Z yourself by turning the black plastic choke knob. It works in the opposite direction to a carburettor idle speed adjustment screw. If you turn it outwards your idle speed will increase. If you turn it inwards your idle speed will decrease.
5. Rocker Cover Bolts
My RM-Z has 14mm-head rocker cover bolts that have threads inside the heads for a bracket. Because these bolts have 14mm heads I managed to strip them really easily. Can the threads be repaired?
This is quite common because the 14mm heads on these bolts encourage people to swing their normal 14mm ratchet or ring spanner off them. These bolts only have a 6mm thread with a 1.25mm pitch. The threads in the cylinder head are repairable using a Helicoil kit. To prevent this happening again, use the shortest 14mm ring spanner you can find.