engine knocking update

[bjrehill]

Hi all,

I just wanted to get a little more input on my engine knocking issue. The engine makes almost a tapping sound after the engine warms up. The carbs are clean and have been bench synched. The air screws have been set to between 1.5 and 2 turns out. It idles at 1050 RPM fine. It just has this knoecking after warming up. There are new plugs that are correctly gapped. All plus are sparking well. The engine runs well above idle and sounds fine. Though it is hard to tell when riding if it is knocking. It is a little rough in first gear between idle and about 2000 RPM. After that it runs fine.

So where should I be looking? The knocking sounds like it is coming from the bottom of the engine, rather than the top. Oil level is fine and clean.Help please. Thanks in advance.

[SqDancerLynn1]

My first guess would be the clutch hub is loose. Remember air cooled engines are noisey

[Anonymous]

Crankit, warm it up, let it idle..
get a piece of rubber hose or broom stick handle, and do the ol ear trick (stethiscope method) and hunt her down.

How many miles on the odo?


oh and is it a "Tapping" or "Knocking"

tapping on top, would be a sign of valves (suzukis have noisy valve trains)

Knocking on the bottom end would be rod bearings (have had this problem) or clutchhub nut loose (never had this problem)

knocking from around the cyls would be wristpins, or worn cylinders, causing piston slap..(had this problem)

good luck,
Ron

[bjrehill]

I have 45,000 Miles on the Odometer. The sound is link the knocking that a car has when it is not getting teh right octane. Almost like a tapping. This started after rebuilding my cam chain tightener and cleanibg the carbs. i will try the tube or stick method to pin point the sound. Thanks for the suggestions.

The sound does not change if I have it in gear or not. It does seem to disappear as I get up to about 2000 RPM.

[pano]

I installed a manual camchain tensioner about 2 months ago at the same time I installed slotted cam sprockets and dialed in my cams.

When I first started the bike I had what sounded like tapping sounds. I thought I had screwed up my cam timing but it turned out I needed to just adjust the cam chain tensioner and put some more tension on the chain.

I would have a look at the camchain tensioner seeing how it started after rebuilding it.

[bjrehill]

Pano,

This is an automatic cam chain tightener(GS850GL 80). I will take a look tonight to see if the piston is where it should be and moving freely. I backed the set screw off till I heard the piston hit the cam chain housing. The tension was good from what I could see, but it is worht a shot. Thanks for the suggestion.

If the cam chain tightener is not putting enough pressure, will it hurt the engine to run it? Thanks

[pano]

I would be afraid the chain might jump a tooth if it were too loose.

[bjrehill]

Thanks Pano.

I think I have found the trouble. When I was setting the pre tension on the outer spring on the tensioner I had the piston on the fully retracted position. It is supposed to be fully relaxed. So there is not enough tension on the spring to keep in in contact with the cam chain blade when the engine warms up.

Learn a new lesson every time. Thanks for all you help.