Guys i have mods listed below and did a compression check sun.All cylinders showed 135lbs.Am i crazy or should i be expecting 155lbs.I have 84 hrs and ski is in good shape.What are stock 97-99 gp12s compression.I didnt do a bfore and after i totally forget.stupid me..Thanks for your input..John
i rebuilt my complete top end all stock.new pistons,rings,cyl and head .on my 1998 gp1200.i tested it after assymbly.135 psi all cyl's.i retested it before i winterized it with 20 hrs on top end ,still 135 psi.
Posts: 107 | Location: long island,n.y | Registered: September 19, 2002
Ok thanks so i guess all my mods and the $500 performance head did nothing and kept my ski stock.Thats rally bad..Thanks for the info.Something must be terribly wrong with my ski.I have to call riva a.s.a.p to find out if i should have gained some compression.Thanks
Thank you for your input well i am almost sure that stock compression for gp12 is 125lbs.So i guess i picked up 10lbs..Wow big deal.I must be crazy i really thought i was going to get 155..Oh well a waste of money...Thanks
compression is effected by how strong your battery is, motor temp, how the test was done, and the gauge itself. if all are at 135 more than likely your gauge reads low.................
Posts: 1755 | Location: - new hampshire | Registered: November 24, 2000
also my motor had 195 hrs on it before i did top end.i had 125 psi cyl 2&3,and 0 psi cyl 1(melted piston)so 125 psi would be around right for a motor with 195 hrs on it,also i bought the ski from my freind who did not break it in at all so iam shure the rings never seated correctly when it was new.so iam guessing 125-135 is normal compression range for a 66u motor as long as all cyl's have the same psi.hope this helps.
Posts: 107 | Location: long island,n.y | Registered: September 19, 2002
also my motor had 195 hrs on it before i did top end.i had 125 psi cyl 2&3,and 0 psi cyl 1(melted piston)so 125 psi would be around right for a motor with 195 hrs on it,also i bought the ski from my freind who did not break it in at all so iam shure the rings never seated correctly when it was new.so iam guessing 125-135 is normal compression range for a 66u motor as long as all cyl's have the same psi.hope this helps.as i stated before my motor is bone stock with 135 psi in all 3 cyl's (mac tools compression gauge)
Posts: 107 | Location: long island,n.y | Registered: September 19, 2002
Ok Battery brand new,Engine temp cold.Gauge was a friends.Only cranked till gauge stopped.New riva head has 41cc domes for a 84mm bore.I have o-rings.What is a usual stock reading.I just want to know if i should have got more compression with this investment.Thanks ,John
quote:Originally posted by yamagaeta1200: Ok thanks so i guess all my mods and the $500 performance head did nothing and kept my ski stock.Thats rally bad..Thanks for the info.Something must be terribly wrong with my ski.I have to call riva a.s.a.p to find out if i should have gained some compression.Thanks
John, It doesnt matter what you get for your ski, there can only be 1 top dog in this little town we live in. HaHa Anyway my 99 read between 120-125 on all 3 cyl. when I bought it with 12 hours last year. That guage we used is accurate. Merc2.4 had a real good point about the battery. I dont know if that could be it cause it did seem like it had pretty good juice. We'll get to the bottom of this, and remember I always have that $1250 if you want to sell it.
Posts: 909 | Location: Ortley Beach, NJ | Registered: April 20, 2003
Mike i got white touch up paint last night for any little nicks i have..So that at least another g-note..yeah???The battery is brand new strong as **** would start up a plane...
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