Jake Posted August 23, 2005 Share Posted August 23, 2005 When doing a compression test should I do the test with all the plugs out or with the other five in place? Also, would worn valve stem seals affect compression test results by any meaningful amount? The reason I'm asking is that I know the valve stem seals need doing on my 100,000 mile RZ engine but I don't want to buy all the parts (stem seals, associated parts, head gasket, etc) only to take the head off and find the ring are shot. I think I'd rather replace the whole engine for a lower mileage one if a rebore is needed. Any thoughts? Thanks Quote Link to comment Share on other sites More sharing options...
Miguel Posted August 23, 2005 Share Posted August 23, 2005 Warm engine, all plugs out, Valve stem seal won't affect it due to a compression check is based upon the Valves being shut. Quote Link to comment Share on other sites More sharing options...
Jake Posted August 23, 2005 Author Share Posted August 23, 2005 Thanks Pedro Quote Link to comment Share on other sites More sharing options...
Miguel Posted August 23, 2005 Share Posted August 23, 2005 De Nadda ..and don't forget to hold the TB open also and pull the igniter pack ...make sure they are at least within 10% of each other. Quote Link to comment Share on other sites More sharing options...
Jake Posted August 23, 2005 Author Share Posted August 23, 2005 De Nadda ..and don't forget to hold the TB open also Really? I've never heard that before. OK mate, will do. make sure they are at least within 10% of each other. How do I do that? Quote Link to comment Share on other sites More sharing options...
Miguel Posted August 23, 2005 Share Posted August 23, 2005 Holding the TB open makes sure you get the full volume of air in the chambers ..otherwise it's just sipping air past a shut TB and give a lower reading and as for the 10% ..The gauge and a calculator Quote Link to comment Share on other sites More sharing options...
JohnA Posted August 24, 2005 Share Posted August 24, 2005 Another important thing is the rate at which max value is reached. It is not the same to reach 170psi (for example) after 20 turns (90-100 120-125-130-133- 135-137 blah blah) or reaching it after just a few (150-160-170-170-170) Fresh rings etc tend to follow the latter pattern. Quote Link to comment Share on other sites More sharing options...
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