BitchenBanshee Posted November 5, 2003 Report Posted November 5, 2003 Question for you port guys. Just bought a new shee with 18cc domes on it. Apparently it was ported by Dan with the Hot Dune Port. I'm getting 143 LBS of compression in both cyls and just wondering if the porting lowers the compression ratio at all. Does 143 sound about right. I'm about 500' above sea level!!! and the numbers reflect a warm engine.. Thank you! Quote
BitchenBanshee Posted November 5, 2003 Author Report Posted November 5, 2003 I was expecting more compression. Does the Port work lower compression? Quote
Blue Duece Posted November 5, 2003 Report Posted November 5, 2003 Does the Port work lower compression? yeah it does, its a shame you dont have a compression reading with the top end fresh, but if you say you have 143psi in both barrels, it could be a fresh top end, if you had 10 psi difference in the 2 jugs, youd know it's time to freshen her up, those charts you see on dome size and compression at the different altitudes pertains to stock bore and port, Dan would be the guy to ask, but im with Jethro that does sound about right and at 500 feet above sea level, your going to have to go with a smaller dome for more compression, i would still consult with Dan, he knows his work, you also wanna find out if the cranks been welded and balanced on your new bike, maybe those domes are there cause the cranks stock? i know if you just up your compression by 50psi youd send that stock crank to the moon..... Quote
Leadfoot350 Posted November 5, 2003 Report Posted November 5, 2003 Hey I had this same question about 2 weeks ago. I just had mine ported too by ted boyko. It is a mild drag port but not so much a dune port. I had 145 with 18cc domes too. I was hoping for 175 like you were so I guess we are safe at what we are at. Now because I am only at 145 do I still have to run race gas??????? I have +4 timming too. Oh and I ride at glamis. Quote
boonman Posted November 5, 2003 Report Posted November 5, 2003 When you change port height and timing, your static compression number will drop. SOmetimes drastically depending on the porting involved. It doesn't mean that you don't have to run race fuel. that is the dilemma with the proposed "160 PSI line" for race fuel or not. I would say that with 18 cc domes, and at your elevation, you had better be running at least some sort of race fuel, or pump and race mixed together..... Quote
Leadfoot350 Posted November 6, 2003 Report Posted November 6, 2003 How much should I add then?? 50\50 of 113 and 91? This is the thing that I dont get. Quote
Blue Duece Posted November 6, 2003 Report Posted November 6, 2003 How much should I add then?? 50\50 of 113 and 91? This is the thing that I dont get. yeah Led you would mix it 50/50 in your case id go 100% race fuel why even bother mixing with the swill we get here in cali we have that MTBE crap in all our pump gas, and you have some cash in your engine, it will help with reliability also, granted it costs us 5 bucks a gallon but well worth it..... Quote
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