The CAM CHAIN is the chain that drives the engine camshaft. When adjusted correctly with the piston stroke, valve train and points in time, the engine will perform as it is supposed to. Often a stretched cam chain can add as much length as an extra link in the chain. A worn cam chain can cause incorrect valve adjustment, point gap and timing in general. First: Before making any of the tests listed check to ensure the engine is in time or in some cases not in time. From the Honda Shop manual (commonly referred to as the Big Blue Book, downloadable from this page) page 2-3; “When cam chain noise is high, the cause is either an inoperative hydraulic cam chain tensioner or excessively stretched cam chain. Incorrect valve timing or valve clearance, or both, are often the main cause to poor compression, low engine power, engine overheating, hard starting, unstable idling etc." "Incorrect valve clearance attributes not only to higher valve noise performance as well. If valve clearance is excessive, the valve opens too late and closes too soon, causing poor engine output, increased fuel consumption, and valve noise. Further, wear of the camshaft lobe is accelerated because the rocker arm is unable to follow the pattern of the camshaft lobe, causing a shock contact. If the valve clearance is too small, the valve opens too early and closes too soon causing poor compression, rough engine idling and back firing. 0.003 - 0.005 in is the normal setting."
Other problems can come from points and a worn points breaker plate shaft. If the breaker plate shaft is worn the point gap of between 0.012-0.015 inch cannot be maintained. Will the engine run, yes, because it will run with a point gap that can shift between 0.012-0.015 inch. When the wear exceeds the gap variance then the point gap can't be maintained and there will be poor idling, rough running, over heating etc. as stated above with a worn cam chain. The same is with the Valve adjustments and maybe piston ring wear can come into the poor performance issue too.
Here, we are addressing the Cam Chain.
To find out if your cam chain is worn there are simple checks that can be taken to find this out. The following is from an article I wrote back in July 1996:
there are some visual checks that can be
Remove the valve/cam box cover and look at the chain.
Here is a worn
crankshaft main bearing
with the chain being worn is the area between the teeth on the cam
Here is a cam showing wear from the chain moving lower between the teeth due to stretching
see Shop Manual page 4-26 for the repair limit. Using a heavy
duty chain with a slightly larger roller will improve this
condition. Often the slipper (top and bottom pins fitted in place
using JB Weld epoxy) will keep them in place and save the
This cylinder with the pins epoxied in
place was used on an engine for over 10 years.
The heavy duty chain has thicker links along with the rollers taking up the wear between the teeth to get your engine timing back. The original Honda chain comes packed in grease the other is packed in light oil. Caution should be taken when choosing a replacement chain. The chain designation is 219T and is 108 pins long. Some can be purchased for as little as $23.00 a chain with another $5.00 for the split link. However many of these chains are used as Go-Cart drive chains and not made for sustained high RPM's like needed on the Honda 600. The heavy duty chain shown costs quite a bit more but will fit, remove the effects of the worn space between the teeth on the Cam and the Crankshaft and put your cam back in the proper timing range. Another question; how do you keep your engine clean? The picture above of the Crankshaft Bearing Cap not only shows the effects of a stretched cam chain but the overheating of the oil which caused the baked on tar like coloring of the aluminum bearing cap.
that is for another letter...
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