VictorK Posted July 25, 2010 Report Share Posted July 25, 2010 I have 20cc domes that are modded,I did a compression test and got 121psi on both cylinders with this tester. the oring is missing that would go on top of the dome so I snugged it up good. I had to use the adapter and want to know 2 things, 1. does this tester give me a lower then actual reading, and 2. aprox what is my actual comp based on the reading this thing gave the compression tester and adapter http://i996.photobucket.com/albums/af82/victorkijonka/comptester.jpg the 20cc modded domes http://i996.photobucket.com/albums/af82/victorkijonka/newdome1.jpg Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted July 25, 2010 Report Share Posted July 25, 2010 whats yo squish at ? you need orings, they seal stuff. with the adapter your using, is the threads the same length as a spark plug ? Quote Link to comment Share on other sites More sharing options...
99bansheeworked Posted July 25, 2010 Report Share Posted July 25, 2010 whats yo squish at ? you need orings, they seal stuff. with the adapter your using, is the threads the same length as a spark plug ? i new what a dome is that the head cover where the spark plugs go in? Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted July 25, 2010 Report Share Posted July 25, 2010 try again ? i dont know what your trying to say. Quote Link to comment Share on other sites More sharing options...
VictorK Posted July 25, 2010 Author Report Share Posted July 25, 2010 whats yo squish at ? you need orings, they seal stuff. with the adapter your using, is the threads the same length as a spark plug ? Im talking about the oring that goes on the base of the adapter, between the dome and adapter. I tightened the adapter snug it didnt really lose any psi after kicking it. I heard on here that these comp gauges give low readings with the adapter, just wondering Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted July 25, 2010 Report Share Posted July 25, 2010 what will read lower is an adapter that isnt as long as the spark plug thread, as the adapter is smaller and takes up less space in the chamber. id find an oring to seal up the adapter to the dome. do you have both plugs out, holding thottle open and kicking till the needle stops ? Quote Link to comment Share on other sites More sharing options...
Larry's Shee Posted July 25, 2010 Report Share Posted July 25, 2010 Wouldn't the shrader valve have to be at the end of the adapter ? Otherwise you have more volume to fill. Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted July 25, 2010 Report Share Posted July 25, 2010 how big is the hole in the adapter ? most adapters have a little hole, so it may be a little off but not enough to see a big difference in pressure. Quote Link to comment Share on other sites More sharing options...
jbooker82 Posted July 25, 2010 Report Share Posted July 25, 2010 Those adaptors will add about 3cc's to get an accurate reading you need the schrader valve in the tip. Any volume before the schrader valve is added volume. Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted July 25, 2010 Report Share Posted July 25, 2010 just cc'd an adapter i had and it held .4cc, which is still enough for a few psi of comp. 3cc would be a big difference in compression. Quote Link to comment Share on other sites More sharing options...
VictorK Posted July 25, 2010 Author Report Share Posted July 25, 2010 what will read lower is an adapter that isnt as long as the spark plug thread, as the adapter is smaller and takes up less space in the chamber. id find an oring to seal up the adapter to the dome. do you have both plugs out, holding thottle open and kicking till the needle stops ? I didnt have the throttle open. Ill try again Quote Link to comment Share on other sites More sharing options...
VictorK Posted July 25, 2010 Author Report Share Posted July 25, 2010 i got 125 psi holding the throttle open, still no oring on the adapter base but when I stop kicking the pressure seems to stay ok. the length of the adapter is the same as a spark plug. my elevation is 1227ft, that makes me think the domes being modded caused a psi loss with my 60 over wisecos. with a elevation of 1227ft and 20cc domes(not modded), what should I be at aprox? Quote Link to comment Share on other sites More sharing options...
dirtydownunder Posted July 26, 2010 Report Share Posted July 26, 2010 probably around 150-155psi on a healthy motor. do a squish test and see where your at... as you say, it could be the domes. Quote Link to comment Share on other sites More sharing options...
VictorK Posted July 26, 2010 Author Report Share Posted July 26, 2010 I wish I could know how much psi the gauges adapter is robbing me of. My motor is healthy, brand new bottom end and 5hrs on top end. Gotta be the domes as you see in the pic. Quote Link to comment Share on other sites More sharing options...
bansheesandrider Posted July 26, 2010 Report Share Posted July 26, 2010 i got 125 psi holding the throttle open, still no oring on the adapter base but when I stop kicking the pressure seems to stay ok. the length of the adapter is the same as a spark plug. my elevation is 1227ft, that makes me think the domes being modded caused a psi loss with my 60 over wisecos. with a elevation of 1227ft and 20cc domes(not modded), what should I be at aprox? Of course it held pressure, the schrader valve in the end of the gauge kept the gauge from loosing pressure, but you could still be losing pressure at the adapter. Quote Link to comment Share on other sites More sharing options...
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