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Swapping out your stock camshaft with a High Performance cam step by step, with pics for your GY6!

Disclaimer: PLEASE read entire instructions prior to attempting this for the first time. Be familiar with the pics and the info to each one, as it may be very important not to skip!!!

This is a technical job. On a scale of 1-10 on difficulty (10 hardest), this one ranks up there close to a 8-9... 10 being engine rebuilding!!!

The job entails use of tools not commonly found in the avarage houshold tool box, so lets get tools sorted out:

You will need:
-1/4 inch socket wrench and socket set... most often you use the 8mm socket, and the 10mm socket... BUT-the Valve tappet is 9mm.
-3/8 socket wrench and set- sockets: 5/8 for spark plug, 13mm for rocker assembly and passenger seat
-metric combination wrench set, specifically 12mm and 13mm for seat
-Feeler Guage set (.003 and .004 specifically)
-3/8 torque wrench and 13mm socket
-Pencil and white-out or etching pen
-Assembly lube
-RTV silicone
-flat-head and phillips-head (star) screwdrivers
-rope or bungee for timing chain

Got those?

First things first, to make your life EXTRA easy, simply use a 12mm wrench and a 13mm socket and 3/8 socket wrench, and remove your passenger seat by removing the two bolts that hold it in place! Remove the seat and you now exposed the whole top-end!

Now... Begin by starting litterally from the top!!

Shut off fuel supply, and drain your carburator....

Remove the carburator and intake manifold. This IS necessary in order to remove the chain tensioner later on. Once you remove the filter/intake tube, the carb, and then the manifold (10mm nuts), you can start removing the plastic components around the engine. You really only need to remove the top section and the passenger (intake fan) side pieces for this task, therefore, it is unneccessary to remove teh exhaust and lower portion of the plastic, however, as I was perfroming other modifications, in my pics, the exhaust is removed.

Use the 1/4 inch socket wrench and 8mm socket for ALL the bolts in teh blastic housing.

Now that you got that stuff out of the way, remove the fan from the flywheel on the passenger side of the engine, again, using the 8mm socket.

Once you have the fan off, take note of where the flywheel is, and remove the spark plug with a 5/8 deep socket and 3/8 socket wrench.

With the plug out, you can partially cover the hole with a finger and turn the engine forward (clockwise) and feel for compression. using the pencil you have, slide it into the spark-plug hole once you located teh compresion stroke. Slowly turn the engine and watch the pencil... If it goes up, turn the engine a tiny bit more... if it goes down, back up a tiny bit till it reaches the top again. You want to see the pencil stick out the farthest, so as soon as you find that (known as Top Dead Center, TDC), you can remove the valve cover and check your status!

Again, using the 8mm socket and 1/4 socket wrench, remove the 2-4 bolts holding the valve cover. Remove the valve cover and wipe the gasket surface thoroughly with a clean rag... set aside and begin timing alignment.

Looking at the cam, line up the two small holes with the top of the engine surface. The large hole should be pointing towards the seats:

If the markings are correct, and you are on the compression stroke, TDC, then you are half way there!! Now, etch or mark your flywheel position so that you can reference it in the future and for tuning later on. I used an etching pen, but many people use marker or white-out.

Once that is marked, you may remove the 4 nuts and washers holding in the rocker assembly. This is 13mm, and the 3/8 socket wrench. Break all 4 loose first, then remove each one at a time. Get your rope or cord ready to hang the chain by....

Remove the rocker assembly from the head, exposing the camshaft. Now, go back to the top of the engine, near the eletrical box, and remove the two 8mm bolts holding down the timing chain tensioner. Remove the tensioner, and be careful not to break the gasket!

Dip the camshaft towards the driver side, and pull the chain from the sprocket SLOWLY. Once the chain is completely off, IMMEDIATELY hang it!! If you drop it into the case, you will have to completely remove your engine from the buggy, and take the entire engine apart to fix it. So hang it right away!!!

Once it is hanging, pull out the old cam! Check the surfaces for scoring or any obvious damages to the head.

Make sure the surface is clean of any oil and or debris, and now you can drip some assembly lube onto the mains, as well as into the bearings of the cam. Drop the cam easily into place, and again, tip it to attach the chain. It is extremely important that the two small holes line up again, even with the head... MAKE sure, check and re-check to have the holes lined up correct...

Once it is in the correct place, lined up and chain on, you may proceed to install the rocker assembly.
Torque plays an important role here... Factory settings state 25lbs of torque were used to install these nuts on the rocker assembly. DO NOT EXCEED THIS!!! Tighen each one in an "X" pattern until snug, then use the torque wrench to get all of them to 25 ft/lbs, in the "X" pattern.

Once the assembly is back on, re-install your timing chain tensioner. Make sure the gasket surface is clean, and make sure it rests on the chain as it slides back into the hole. Tighten them up with the 8mm socket, and now you can move onto the hard part!!!

Now you need to set your lash. Valve Lash is the amount of travel the rocker and tappet have before coming in contact with the valve stem. To set your lash, you will need a feeler guage set with .003 and .004 guages:

Starting with the intake valve (top):
Loosen the adjusting nuts on both the top and bottom (intake and exhaust) tappets with the 9mm socket and 1/4 inch socket wrench. Once they are loose, you should be able to spin the square head screw with your fingers or a very small set of pliers. Place the feeler guage (.003) between the tappet and the valve, and tighten the tappet screw untill it touches the guage. Pull and push the guage...There should be tugging tension, but not too tight that it scores the guage. Once it is taught, tighten the adjusting nut with the 9mm socket, and re-test the lash with the guages. Check and re-check to make sure they did not loosen while you tightened the nut.

Repeat this step for the exhaust valve, only, some manufacturers recommend that you use the .004 for the exhaust valve instead of the .003. I checked my depth BEFORE removing the rocker assembly, and I found that both were set at .003.

After re-checking 3 times or more for each valve lash, I felt comfortable with my settings, and now it is time to close up!

Using a small bead of black rtv, I made a new gasket and re-installed the valve cover:

Now, just re-install the fan, the plastics, the carb and intake and all other components that were removed, and you can finanlly test out the performance!!!

IF you experience hard starting, or a no-start condition, the your timing is off. If you experience back-firing or constant popping, you may have been off by a few teeth or even 1 or two on the chain and cam gear. you will need to go back in and re-set the chain on the cam if this is a problem you experiece. That is why it is sooooooo important to line up the wholes of the cam in the beginning.

If you have a no-start problem, or it back fires but doesnt run, then you most likely are 180* off, or were on the wring stroke when you set your timing marks. Again, you will have to remove everything and re-align the marks and TDC to assure proper timing.

This is not an easy mod, and tuning will need to be stepped up as soon as this mod is completed. Better intake if not already installed, better jetting, most likely a larger jet is necessary. New spark plug is recommened. And exhast modifications may be necessary to enduce the highest level of performance from your new mod!!!

Good luck, and hope this helps you out if and when you decide to go big!!!

John Mackey Very Happy

More pics of the job!!!!!

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