Tuesday, October 02, 2012

Simple Guide to Valve Adjustment

Written By: GearHead.com

So you just got a killer deal on a bike on CycleTrader and you want to make sure everything is in tip top shape before your big upcoming ride. Whether you know if your valves need adjusting or not, it’s a good idea to at least check them periodically, especially in bigger or high compression engines where valves need to be adjusted more frequently. This simple guide will get you started with the basics on how to check and adjust your valves. This guide is for most 4 stroke motorcycle engines, but does not cover every make and model, so consult a repair manual for specifics for your bike. Valve adjustment can seem intimidating but it’s fairly simple on most bikes and can save you lots of money in the long run instead of having to take it to a mechanic. 



What You Will Need:
·         Valve clearance specifications (Exhaust and Intake in mm)
·         Basic knowledge of your bike (how to get to TDC)
·         Feeler gauges – Feeler gauges that match the specs you need to measure. (Some automotive feeler gauges are too big) Any local auto or motorsports store should carry some.
·         Basic Tools – Basic tools like screwdriver, sockets, pliers, and wrenches to remove the valve cover, sparkplug, and turn over crankshaft nut.
·         Valve cover gasket – Just in case the old one is bad or gets damaged. (Always buy factory OEM gaskets)

How to check and adjust the valves:
1.        Remove spark plug(s).
2.        Take off valve cover and set aside. They may need a love tap from a rubber mallet to break loose. You should be able to see the rocker arms and valve stem/springs at this point.
3.        Crank the engine over so that the timing marks point to top dead center (TDC) and it’s at the top of the compression stroke. Rocker arms on intake and exhaust will usually have slight amount play in them since all the valves on the cylinder will be closed. There is usually a timing mark you can view through
4.        Check valve clearance by measuring the gap between the rocker arm and the valve stem with the feeler gauge. (see photo at right)
a.        If valve clearance is correct, there will be a slight drag felt on the correct feeler gauge. If the gap is incorrect, you’ll need to adjust the valves. If you have a shim type valve, you’ll most likely need to remove the rocker arm to replace the current shim with one of the correct size. This may mean more work to make sure that timing isn’t affected and trial and error to get the right shim size. Consult your bikes repair manual for specifics on your bike. If you have a screw and locknut style valve adjuster, then you can simply loosen the locknut and adjust the screw to the correct specs.
5.        Set valve clearance with adjusting screw and then tighten locknut. Check the clearances after the locknut is tightened then replace the valve cover (with new gasket if needed) and tighten in crisscross pattern. (Do not over tighten!)
6.        Do the same for all valves on that cylinder and then move on to other cylinder(s) using steps 2-5.
7.        Install spark plugs. (Do not over tighten!)
8.        That’s it! Now go out and ride that freshly tuned beast like you stole it.

If you run into or cause any broken parts along the way, (bolts, gaskets, etc) be sure to replace them with genuine factory OEM motorcycle parts. Gearhead.com offers free online parts diagrams and sells millions of OEM and aftermarket parts, gear and accessories for all major makes and models of motorcycles.
Note: For a more in depth guide on valve adjustment, please see our other article, “Howto Adjust Valves on a Motorcycle or ATV.”


9 comments:

Edith Canon said...

Thanks for this, now I am able to make adjustments to my motorcycle valve. It really is a bit intimidating when you talk about valve adjustments. This guide surely is a great help to me. TheCycleExchange.com

Rachel Matteson said...

Great blog. I has everything I need. You see I'm helping my husband for his upcoming bike trip with a couple of his closest friends. I don't want him to have problems during the trip so I'm researching a bit.
- TheCycleExchange.com

harris said...


that's very simple idea....
for guide valve adjustment...
http://www.fence-etc.com

Rachel Matteson said...

Thanks a lot for this. It really is simple when you have a good teacher posting a good blog. :)
- TheCycleExchange.com

Rachel Matteson said...

I always let the mechanic do things like this before because I don't want to touch anything that can possibly ruin the bike. Now that I know that it is fairly easy, I can do it myself. Thanks for showing me how. :)
- TheCycleExchange.com

Rachel Matteson said...

Very infomative blog. I wouldn't know what to do without reading this blog. So useful. :)
- TheCycleExchange.com

Goyen Solenoid Valves said...

I went through several plastic splitters like this before I broke down and went brass.

Every single one of the plastic ones broke down in the desert sun and cracked in a single summer. These are holding up flawlessly so far, and I don't expect them to fail any time soon.

Even if it costs three times more, do it. Brass will last much more than three times longer than plastic.

Rachel Matteson said...

I see. So that is how important valve adjustments are. I knew that it is part of maintenance but I just don't know how to do it. I usually hire a professional to do it when it is just so easy. I'll try doing it myself next time. Thanks for this.
- TheCycleExchange.com

Rachel Matteson said...

Getting the bike in top condition before a ride is very important to make it function without fail since the journey ahead will be quite long. Besides, you can enjoy the trip well when not worrying about the bike so much. :)
- TheCycleExchange.com