14)  Remove the Spark Plug boot and the Spark Plug.

15)  Remove the 3 bolts holding the valve cover on and remove the valve cover.

16)  Remove the Crankshaft Hole Cap to set the motor to Top Dead Center (TDC).  TDC is achieved when the two marks align.

***Remove this bolt to align the marks to TDC***

17)  Once you have achieved TDC (you can do this by moving your R forward in gear) you need to secure the cam chain to the sprocket with two large Zip Ties.

***Note*** There are two TDCs on a 4 stroke engine, make sure your cam lobes are pointing to the rear of the quad like the picture.

***Zip Ties installed***

18)  Remove the two Allen head bolts holding the sprocket to the camshaft.  I found this to be very difficult as they are secured with lock-tite.  Get a good pair of leather gloves and one person needs to grab the sprocket and hold on for dear life.  Person number two needs to insert your Allen wrench and tap it with a hammer to break them free.

***New method***  Insert your Allen wrench and put quad in gear and have person 2 step on rear brake to hold cam sprocket in place.

***Here are the two Allen bolts in the sprocket***

19)  Cam Chain Tensioner…there are different thoughts on removal of this.  Here is what I did and I found it very simple.  Take the end bolt out of the tensioner and insert a small flat head screwdriver.  Turn the screwdriver clockwise until it stops.  All of the tension should be removed from the chain and you can slide the sprocket off.  Do not let go of the screwdriver!  Ease it back turn by turn until it is free…it is spring loaded.

***Insert flat head and turn clockwise to release tension***

At this point I would recommend you check the clearance on your valves.  I wish I would have checked mine before I removed the cam.  It is not necessary but I wish I would have known.

20)  Remove the four bolts holding the cam assembly.

***Remove these 4 bolts***

21)  Steadily lift of the cam assembly taking care not to drop any of the shims into the motor.  The assembly is positioned with bosses just work it back and forth gently and lift up at the same time and it will come off.  If any of the shims come off make sure you place them back on the correct valve.

***Here are the shims***

22)  Remove the decompressor bolt from the cam assembly.  I used a pair of vise grips but some have used a vice.  The vice grip method worked wonderfully.

***Remove this bolt (decompressor)***

***Here are the vise grips I used (two person job)***

23)  Remove the snap ring and the cam shaft will slide out.

***Remove this snap ring and the cam will slide out***

24)  Slide the HRC Cam in and reinstall the snap ring.  Apply Lock-Tite and install the decompressor bolt.  Torque decompressor bolt to: 18 lbf-ft.

I used Lock-Tite #243.  It is an oil-resistant medium strength formula (blue) readily available at the parts store.  I consulted Lock-Tite and my dealer on which product to use.

25) Reinstall the cam assembly and torque the four bolts to 10 lbf-ft.

26) Use a feeler gauge and check your valve clearances.

      Exhaust: .28 mm +/- .03 mm

      Intake: .16 mm +/- .03 mm

***Note*** There are two TDCs on a 4 stroke engine, make sure your cam lobes are pointing to the rear of the quad like the picture.

***Checking one of the Intake valves***

***Checking one of the Exhaust valves***

After you check all the valves you may need to make shim changes.  The easiest way to explain this is find the correct thickness of gauge where it will slide in an out with just a little tension or pressure on the gauge.  All of the shims are numbered according to how thick they are.  It sort of works backwards, if you can properly fit a .220 mm (exhaust valve example) gauge in then you are too tight even though it is a smaller number then the required .28 tolerance.  Therefore, you add a smaller numbered shim to increase the amount of space so the larger .28 gauge will fit.  In the above example if a .220 fits then you probably need to drop .06 on the shim.  So if the factory shim is a 215 then you need to get a 209.  It is not an exact science because I was still .02 off from dead on .28 mm.  I worked mine a while with different shims and all the valves ended up dead on.

27) Check the clearance on the decompressor arm:

      Decompressor: a* + .25 mm +/- .02 mm.

a* = adjusted exhaust valve clearance.

Basically take the exhaust valve clearance you have and add .25mm +/- .02mm to get the clearance for the decompressor.

28) Mix your Molybdenum and motor oil in a 50/50 solution and apply to the top off the shims, lobes on the cam, rocker arm and lifters.  I used Moly Paste, my Honda dealer did not have anything else, but it worked great.

***Moly/motor oil solution***

29) Ensure you are at TDC, turn the screwdriver in the camshaft tensioner fully clockwise and reinstall the cam sprocket and chain.  Ensure the alignment marks line up, (there are two marks on the sprocket and two on the camshaft holder) apply Lock-Tite and torque the sprocket bolts to: 14 lbf-ft.  You can now remove the Zip Ties.

***One of the cam gear marks (there is another on the right side)***

***Alignment mark on the cam assembly (there is another one on the left side)***

30) Now begin reassembling your 450R.

      Torque Specifications for Re-assembly:

      Head cover torque: 7 lbf-ft.

      Spark Plug: 17 lbf-ft.

      Crankshaft Hole Cap: 11 lbf-ft.

I would like to thank 370KingR, whom I called in the middle of the night!  I would also like to thank my dad for his help…I am 33 years old and still calling dad for help…the way it should be!  And of course my wife…for letting me work in the garage all day on my R that is 3 weeks old while she is in the house with the 8 year old, 6 year old, and 9 week old daughters…god bless her.