cam chain rattle...

[johnnya]

can anyone advise...i have a cam chain rattle, think it just needs adjusting...is this an easy thing to do ??  any advice is well  welcome..cheers

[CB750Winger]

  What model do you have and do you have a shop manual for it? On the SOHC models, all you have to do is turn the bike over to the correct timing mark and stroke and adjust the tensioner bolt. The tensioner is spring loaded. If you have a SOHC bike, I can explain from the manual for you.           Paul

[johnnya]

yes i have a manual, thanks,

[Re-run]

What year of bike though?

In my HONDA manual for the K8/F3 bikes, it says to start the engine and allow it to idle. Loosen the nut and the bolt for the cam chain and the tensioner will adjust itself. As all the sohc engines were the same, this would work on the 69-78 models.

You can also pull your plugs or at least loosen them and then pull off the points cover. Set the timing to the T mark and then back up about 15 degrees and then loosen the tensioner and it will do its thing and just tighten everything down.

Either way works on the sohc bikes.

[CB750Winger]

  For a little more detail, on the 69 - 78 SOHC models, rotate the crankshaft clockwise to 15 degrees after top dead center on #1 cylinder. With the point cover off, this will be the 1/4 set of points at the timing mark. 15 degrees is at the top center of the little spring peg below the "T" mark. Pull the spark plugs to see if it is at #1 or #4 or both valves will be closed and rocker arms will be loose. This position puts the chain slack at the rear of the engine and duplicates running conditions. Then loosen the chain adjustment locknut and bolt. This releases the bar inside and allows the spring to automatically adjust the tension on the chain. Now tighten the adjustment bolt and locknut. It's pretty easy after you do it once. I hope this helps.

[Re-run]

I wonder if manuals changed over the years. I have the actual shop manual from honda and it says to do it while running but the static way is ok too.

[CB750Winger]

   I agree, you could do it running but I don't trust it. I did that with my 75 Kaw 900 Z1 DOHC years ago and took several times to get it. I think one of the cams was moving slightly or if you get a misfire or hickup while running, might as well do it the static method. That way you know the slack would be in the right position, as little as it may be. Just my opinion.

[Re-run]

I actually always did it static. I was just point out the factory manual says to do it running. I suppose if the unit is working right, it probably makes no difference., depending on the bike of course.

[CB750Winger]

  I would agree re-run, it depends on a few things and the manuals are different, I mean between Honda, Clymer, etc and how the bike is running. There are sometimes several methods to accomplish the same task so at least we've thrown a couple of good options here. I happened to have the valve cover off my 750 replacing the gasket when I adjusted the chain so I could also tell the notch on the cam was in the right place. There's a lot of good info here.

[Re-run]

I suppose manuals also changed over the years too. That always makes things fun.

[johnnya]

thank guys, i`ll give it ago.....and let you know how things go..john

[sam]

IMPORTANT   the cam chain tensioner on the cb750 is spring loaded but spring is not strong enough after after years of heating. Its a basic flaw.  To get some room, remove the air filter assembly and the remove the 3 screws that hold the tensioner. Remove the tensioner.  Make sure that the mechanism in the engine that the tensioner pushes on moves freely.  Mine was stuck solid. I sprayed some penetrating oil and waited overnight and tapped on it with the end of a small vice grip and it loosened up.  Now disassemble and clean the spring loaded tensioner. Notice that there is a hole at the end of it where you can push an ice pick or small screw driver in to push the rod in that would normally be pushed by the weak spring. So first replace the tensioner mechanism , tighten the 3 screws, loosen the bolt, push the rod in from the hole in the end and while pushing tighten the bolt.    The tensioner mechanism is a weak design but the procedure I described will work.    Even if you disassemble your entire engine, replace the cam chain and the idler pulley inside the engine, the spring loaded tensioner will not work properly. If the wheels in the idler pulley are still in reasonable condition, the procedure I described will do wonders . It really doesn't matter if you do it with the engine running or not running. If you do it with the engine running you will hear the rattle decrease as you push on the rod in the tensioner mechanism. The idler wheel in the engine is made of black rubber.  When you change your oil, if you don't see any little pieces of black rubber, there is a good chance the idler pulley(this is what the spring loaded rod is pushing on) is still in reasonable condition.   Replacing the pulley is a big job because you need to remove the head and more so you want to avoid it if you can.  The procedure I described is actually very simple, the hardest part being the removal of the air filter housing. So you might as well replace the air filter.  

[pat english]

Re-run wrote

What year of bike though?

In my HONDA manual for the K8/F3 bikes, it says to start the engine and allow it to idle. Loosen the nut and the bolt for the cam chain and the tensioner will adjust itself. As all the sohc engines were the same, this would work on the 69-78 models.

You can also pull your plugs or at least loosen them and then pull off the points cover. Set the timing to the T mark and then back up about 15 degrees and then loosen the tensioner and it will do its thing and just tighten everything down.

Either way works on the sohc bikes.

wow this is crazy stuff.i just tryd to give a guy some advise.i think i was dead wrong.these bike are NOTHING like a harley.i know nothing.

[jon]

what do i do if its already loose?, the cam chain that is.

[Re-run]

How many miles on the bike? If not much more than 20,000, then try to let the cam tensioner do its job. Depending on your bike, you may need to clean it first.

[TOOLS1]

Are you sure it's the cam chain. If the carbs are out of sync it will sound just like a cam chain rattling around.
TOOLS

[MR.FATS1]

i have a 1979 honda 750L AND NEED HELP WITH CAM RATTLE

[TOOLS1]

Just sync your carbs, and it should go away.
TOOLS

[MR.FATS1]

WHAT ABOUT 79 750 L MODEL

[TOOLS1]

That one also. If there are more then one carburetor, they need to be synced. When that engine is out of balance it will sound like the cam chain is having a snack. I know of several of these old bikes that have sat, for years because the owners thought the engines were going bad, and all they needed were a tune up.
TOOLS