GS-R knocking

Last summer, my '94 GS-R started having a problem with a very light knock under load at low rpm. The problem has slowly gotten worse in that the knock is noticeably heavier now. Not really a problem - yet
- but it has gone from curiosity to annoyance. The car has 145K of hard use. Generally maintained well but may be coming due for some routine items and about 30K since its last valve adjustment. I use Mobil 1 but I only change it twice a year. Engine all original and stock except for a header to replace the noisy A-pipe. Other than the knock, the engine runs great like always.
Any ideas?
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Try Premium gas.
Check ignition base timing.
Motorvac service to remove deposits from combustion chamber.
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I should have mentioned that I only use premium per Honda reco.

Good idea.

Is there any way to determine if this is needed?
Thanks for the suggestions.
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The first thing that you should do is to adjust the timing--If you have never done this before--have a mechanic do it for you.
If that does not solve the problem, you should have a complete tune-up. Mechanics use a Diagnostic Computerized Engine Tester when performing a tune-up. That means the mechanic can easily find and repair any problems that are the cause of the "knock". When I had a "knock" problem--I solved it by adjusting the timing but there are other causes. Also, attempt to find out whether or not your car has a "knock sensor". If it does have a knock sensor--it might need to be replaced.
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Your GS-R has anti-knock sensors. This means it retards the timings when the car pings. Usually, the computer should throw a engine code when they malfunction, as it's doing in your case. Maybe something else is wrong with your engine? Too much carbon in the intake? worn plugs? cables? distributor cap?

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What kind of knock are you having? I noticed my 95 Civic EX havindg a little piston slap on cold mornings that I completly eliminated by using Castrol GTX High Milage oil.....Next,I also use plus gas to keep engine knock completly under check. Paying an extra 10 cents a gallon for gas for me equals about $0.75 per week. The Honda Acura engines are very high performance and I suspect my milage may even be a little bit better using 89 octane. I know eliminating piston ping will contribute to the longivity of my engine.
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On Sun, 12 Mar 2006 00:44:02 -0500, "duckbill"

No piston slap, just a couple knocks if I give it too much gas at too low an rpm. Already using premium gas because that is what the engine requires.
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