If a fourwheeler is starting hard and it has a 4 stroke engine, a common problem is that the valve clearance is out of tolerance. Today I will be going through the steps of checking this and adjusting for it. I have been racing these machines for 8 years and working on them since I was little.I have a lot of experience with these machines which also means I have done this process many times. It can save the average person a big amount of money by doing this themselves instead of having the dealer do it.
Step 1: Tools and Materials
Tools needed for this job will be the following:
1. Torque Wrench
2. Metric Allen Set
3. Torque Wrench
4.17 and 10 mm sockets
Step 2: Removing Plastics From ATV
Using the metric Allen key set, remove the Allen bolts holding them to the frame. Most will be size number 5 with some number 4 bolts as well. Removing the plastics will offer the required space to get into the engine. To make re assembly easier, make sure to screw the bolts back into the holes on the frame.
Step 3: Removing the Timing Plugs
Now that the plastics are removed, the engine plugs can be removed from the engine. They will be a size 8mm allen key. Removing these plugs will reveal the 17mm nut that is required to turn the motor over to top dead center. Make sure that the T mark on the flywheel lines up with the arrow inside the top hole.
Step 4: Veryifing Top Dead Center
Now that the engine is at top dead center, the valve cover can be removed. Use a 5mm allen key to remove the two bolts holding the cover on. You will see the camshaft and the dot lined up with the line of the head, and one dot at 12 o clock.
Step 5: Checking the Valve Clearance
This the main part of this project. Using a set of feeler gauges, start with .005 feeler gauge and slide it under the camshaft. Keep going up in size until the gauge will not slide under. The last gauge to slide in is the clearance for that valve.
Step 6: Re Assembly
In the last step the valve clearance was checked. Both were in tolerance so no further action is needed. The atv can be re assembled the same way it came apart. All bolts should be in their respective holes or in a plastic bag. Make sure to use a torque wrench so the bolts do not end up being over tightened. Also be sure to tighten the two 10mm bolts on the top of the atv.
Step 7: Testing the Engine
To insure the process was done correctly the engine should be started and carefully inspected. Any loud knocks or ticking sounds is a bad indication that something wasn't tightened, or the valves may not have been set correctly. If no noise is detected then the atv is safe for operation again. Thank you for your time and interest in my presentation. I hope you learned something new, and that with patience and good instructions anybody can be their own mechanic and save themselves a lot of money. If you have any questions please don't be afraid to email me. I loved to help anybody who is interested in riding or racing.