What is the adjustment procedure?

From Ninja250Wiki
Revision as of 21:53, 8 September 2006 by Payne (Talk | contribs)

Jump to: navigation, search

Valves should be adjusted when the bike is COLD.

Put the bike on centerstand. Take off the lower and upper fairing, side covers, and fuel tank. Carefully pull the spark plug wires by their boots, and remove the left and right coil packs (two 12mm bolts each). Note when reinstalling them, the red wire goes on the bottom on each coil. The service manual suggests draining the coolant so the radiator can be removed to make it easier to reach the exhaust valves, but it is possible to avoid this, however, by removing the fan (3 small bolts and a wiring harness) and unbolting the radiator (4 bolts plus two that hold the filler neck) grants better access since the radiator is free to flex by its hoses. You can also remove the 'wings' from which the front of the engine is hung (one long 14 mm bolt, the four bolts holding the two ignition coil brackets, and the two lower radiator bolts), which makes it much easier to reach the exhaust valves and makes removing the valve cover a no-brainer (otherwise, it requires some finessing to get it out.)

Remove the alternator cover and flywheel view cap on the left engine side cover (use a very large flathead screwdriver or a nickel in a pair of vice grips). Take out the two spark plugs. While this is not mandatory, it does make the job much easier. It lowers the compression of the engine to essentially zero, making it easier to turn over, and more likely to stay the way you left it (instead of trying to turn over a bit more due to air compression.)

This also means you should replace, rather than re-use, the plugs' crush washers. But again, it's not MANDATORY. That said, the torque spec of "finger tight plus 1/2 to 2/3 of a turn" no longer applies once the gasket has been crushed, so you really have to be careful re-using them. So, unless you have a supply of NGK crush washers at hand, it is HIGHLY RECOMMENDED that you put in new spark plugs after you adjust the valves. You can afford the four bucks.

Take off the four valve cover bolts and lift off the valve cover (do not remove the cover gasket; leave it on the top end). Using a torque lever (large socket driver), turn the engine using the alternator bolt inside the left cover housing; turn the bar forward (counter-clockwise) until the cam lobes over the left cylinder cam lobes point out and slightly up. (They should mirror each other, as in this image.)

Cams tdc-1-.jpg (cam lobes out and slightly up)

When this is done this correctly, a "1T" mark will be visible on the flywheel through the view hole (you'll need a flashlight to see it), and the tappets below the cams will wiggle when you try to move them under your finger.

Here is a photo of the engine at TDC for cylinder 1:

Tdc 1t.jpg

Now take out your feeler gauges, and slide the proper gauge finger under the first cam (of four for that cylinder), between the cam lobe and the top of the valve tappet; it should slide in with little effort, and drag slightly when the clearance it correct. The factory clearance specifications are .08-.13mm (0.003-0.005 inches) for the intake valves and .11-.16mm (0.004-0.006 inches) for the exhaust valves. A common mistake is to use the metric values with SAE feeler gauges, so double-check this.

If the clearance is not correct, grab a long 1/4" drive 9mm socket and loosen the tappet locknut; there's a small screw on top of the nut. Use a very small flathead screwdriver (an eyeglass screwdriver workers great) to turn the screw out a bit until the clearance is correct (if you use the looser end of the acceptable adjustment range, it will take longer before the valves need adjustment again.) Note that you shouldn't need to turn the screw much at all; if you're turning it a lot, something's not right - double-check the cam lobe position and your feeler gauges.

Tdc 2t.jpg

Rotate the engine again until the right cylinder cam lobes (above) are in the proper position (a "2T" mark will be viewable on the flywheel), and repeat the check/adjustment process. If the exhaust valves need to be adjusted, you may need to remove the radiator retaining (four 10 mm) bolts to move it out of the way (the coolant hoses will keep the radiator loosely attached to the bike), and it also helps to remove the fan (three small bolts hold it on, then slide it downward.) The exhaust valves tend to take longer to work on.

NOTE: Torque value for tappet locknuts: The original manual says 14.5 ft/lbs. Supplement says 13 ft/lbs. It's recommended to use about 12. It's not worth stripping those things.

Wipe the valve cover gasket clean of oil and put everything back together carefully when done. Use very little torque on the valve cover bolts; the book calls for 87 in/lbs (if you don't have a torque wrench, then tighten them by hand followed by a 1/8 turn with a 10 mm wrench to seat them).

NOTE: You should sync your carbs right after you adjust the valves.

Hints & Tips: Valve Adjustment

Other Valve Adjustment Articles

Barbie Does Valves

ForceOne Technologies

SC Squared