When i start the bike the motor makes a knocking sound while warming up i was told it was the decompresser lever on the cam making the noise and was also told all 4 stroke bikes makes this noise after rebuild

Have your valve lash adjusted. Overhead cams need the lash done every 25-30K otherwise after some time they make a loud ticking sound. If the motor makes a "Knocking" sound, it may be a lower end noise, and there is no adjustment for that.

Sounds like a tapping maybe lifter. Maybe valve check under valve cover.

I have one of these also. Push lightly on kickstart until compression is felt. Pull in the decompression lever and press kickstarter down another 2 inches, release the decompression lever, and and then let up on the kickstarter to get a full swift kick. It seems like alot to do, but once you get the hang of it, it really is easy. Also, I upgraded the copper spark plug (NGK CR8E) to an Iridium one (NGK CR8EIX) and it made it much easier also.

Also, I have heard that an exhaust cam from an ' 03 YZ450F has the same cam lobes, but with the built in auto-decompress will swap straight into this bike, I was looking into doing this with mine, but just got so good with the above procedure I did not waste the money on it.

Standard starting procedure for YZ400/426/450 is as follows: Push the engine around using the kick starter until you hit the compression stroke. The kick starter will get impossibly hard to push at this point. Now pull in the decomp lever and push the kick starter down a fraction, and I mean a FRACTION. This is where most people go wrong, they push it down too far with the decomp lever pulled in. Now give it a full kick without throttle and it should start.

The above should work fine for a motor that's already warm and was NOT stalled. If the motor stalls it will usually need the hot start button opened as well to let extra air in and bleed out the fuel that usually gets stuck in the motor when it stalls.

For cold starts, you will need to put the choke on, and if it's really cold you might need to prime the engine with a twist of throttle to get the accelerator pump to shoot some fuel in before you start.

As a general rule, NEVER twist the throttle while kicking when you are actually attempting to start the bike, it won't help at all. Also, having your idle screw adjusted correctly makes all of this a lot more easier. Standard setting is usually 1.5 turns out but it should be set to give the smoothest idle you can get using the minimum number of turns out from all the way in. If you have to wind your screw right out to get a good idle you need a bigger pilot jet. Conversely if you have to wind it most of the way in (less than 1 turn) you need a smaller pilot jet. I'm not sure about the 450 but my YZ426 came standard with a 42 pilot jet and changing to a 45 made it idle and start MUCH better. Incidentally the WR model uses a 48.

Hello Gabe,

If the "knocking" noise sounds like it's coming from the lower end, listen to see if it's around the clutch area. My was making a "knocking" noise, only on cold starts, which sounded like the bike was trying to engage into gear. I drained the fluid from the clutch system and refilled with clean DOT 4 brake fluid. This stopped the problem.

Ironically enough, I was having the "ticking" problem too. When I would start my bike, about 30 seconds into warming it up, I heard a ticking noise for 2 -3 seconds of the right side of the bike. The Wing uses a hydraulic Valve and Tappet system which will, eventually, make noise if you run "low grade" fuel in the Wing. Go to your local Wal-Mart, or parts store, and buy a can of Sea Foam. Follow the directions on the bottle for the amount to use with a full tank of fuel (add it to your gas tank, not your crankcase). Fill your tank with Premium fuel and add the Sea Foam. Do this for two fill-ups and this should clean your valves and clear up your noise(s).

NOTE: any fuel with Ethanol in it is NOT good for bikes or cars and will cause buildup on your Valves. Sea Foam ALWAYS works. This is a cheap way to find out if it is just deposits or if you are going to need a mechanic.

Oz

Remember all Honda's are cold blooded. Make sure your gas is on, full choke, pull the decompression lever, no throttle, kick the engine over 3 or 4 times. Let go of the decompression lever. Now start the bike.

The tappets in your engine are hydraulic and there is no adjustment to them. As the engine warms up and expands, the tappets expand to maintain zero backlash. I've seen the rollers on the end of the tappets go bad and when they do, it sounds like someone with a sledgehammer in the motor. But, I've never seen one go bad at 3000 miles. The earliest I've seen one go bad is 13K miles.

If I had to guess, with only 3000 miles on a 2001 model bike, I'd guess bad gas. Put some fresh gasoline in the tank and make sure that it contains no more than 10% ethanol.

Good Luck
steve

The problem you describe sounds like a loose cam chain. Remove the cam chain tensioner and check for proper operation. Your bike is getting older, it may be time to replace the timing chain and / or tensioner dampers. Go to www.babbittsonline.com/parts/viewbybrand/parts.aspx to get parts.Please rate my answer. Thanks.

it may need a lifter or valve adjustment when cold they will tick or knock depending on how loose or worn out then when it warms up they swell with heast and noise stops. after adjusting or replacing it will stop making noise

hold the decompression lever in and kick it slow then let go of the decompression lever and give it a good kick without using the decompression lever.