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Thread: 440cc compression readings

  1. 03-17-2003, 08:05 AM #1
    e gracie
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    440cc compression readings

    440 any ideas what the comnpression reading should be? pretty sure bang on 11:1 now @ 160psi is this to high?
    am getting some pre ignition @ the mo uping the pilot to a 45 as soon as it comes but plug does look a lovely colour..
    dont want to have to run race gas if i can help it...
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  2. 03-17-2003, 07:21 PM #2
    e gracie
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    some one must of dun a compression reading surely .pretty plz
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  3. 03-18-2003, 08:03 AM #3
    e gracie
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    absolutley no body has dun comp reading on a 440
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  4. 03-18-2003, 02:34 PM #4
    Steven
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    nope, but i do run cam2 100 octane gas and I don't get any ping...
    TRX440EX: Ross 11.2:1 piston, Advanced Sleeve-sleeve, Hotcams Stage 2 cam, P&P head with port matched intake and 3 angle valve job, Uni filter, White Brothers Pro-Meg exhaust and rev Box, stock carb w/choke removed 172 main, 42 pilot, needle on 4th clip (no air box lid), OMF scoops, Elka shocks

    04' YFZ450S: HMF exhaust, cam mod, Alba Pro-flow w/K&N
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  5. 03-18-2003, 08:03 PM #5
    e gracie
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    only get 94 octane over here. if u lucky u can get 96.oping the bigger pilot jet will get the temp down a little but i know its going to be a tad rich then.........and i beleive octane boost is a no no in these engines vp fuel by the looks a things........
    this is why i want comp readings as if its a little to high i can up the head gasket to a thicker 1 an get away from the problem ,also a little worried if the rod is under to much stress '@ this psi
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  6. 03-19-2003, 03:29 AM #6
    fourtrax400ex
    fourtrax400ex is offline Best on Earth!!
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    about compression, my 426 when it was new has about 180-195psi, i ripped the motor this winter and put new ring and also a new battery(so the motor crank more rapidly) and check my compression and have 220psi?????!? so im not sure if is my compression tester or the fact that the motor crank more easier or maybe you cant really trust psi, but with a 440, bigger the piston is hotter the motor is so i think it will be best to run race gas to keep it cold, if you cant have race gas, chekc for an airport an get some 100LL, i run this in my 426 , 50/50 mix with super and it run great and clean. i dont think that 160psi is too much for the crank,

    my two cents
    Brand New 450R, First on the List!!!!
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  7. 03-19-2003, 07:48 AM #7
    e gracie
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    220psi and i was worried.. possibly higher after a rebuild due to oil on rings should of droped back down by now
    .many thanx for u r imput looks like i am going on a 50/50mix ..if its hot now its going to be hotter in the summer...
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