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  1. #1

    Piston Wash and Comp #'s

    Ok I changed out all the ss bolts from the riva rec heads today and head gasket due to 3 bolts that broke on the rear cylinder while riding. I snapped some pics of the wash to see what everyone thinks. I also checked my compression which is pretty much the same since I installed the heads the rear is 130 the middle and front 137-139. Should I send the heads to Lowell to have them milled for 150-160. I am turning the 14/20 dynafly to 7170 right now and best I have hit is 71mph on gps. I am really hoping for 75. All of my mods are: pro x pistons, vf3's,riva rec heads, 3 degree keyway, dplate, carbs have accel pumps blocked off and choke plates removed,dual fuel pickup mod, with flapper door removed, oil pump blocked off, r&d power plenum, jetworks mod, r&d free flow, visibiltiy spout and siphon blocked off, 85mm nozzle, HO pump with 14/20 dynafly, r&d 1200 grate, IR mod 4 r&d plate, ppk, shoe sealed, tunnel reinforced and upgraded brackets. I think I have pretty much every bolton that I can get just short off going to a 1390, porting or throwing a 1300 top end on it. Would sending the heads to lowell be worth it?????? Should I just send the stocker or send riva heads? Here are the pics of the pistons




  2. #2
    ok I am sending the stock head off to be milled to hit the 150-160 compression numbers I am looking for. Will this raise the rpms at all? What will I expect to see off the 130-137 I am seeing now? I am turning the 14/20 at about 7170 right now just want to know when you have to pitch up. Seems like I am really spinning the prop outta the hole too. Also what do you guys think of the piston wash pics?
    Last edited by whiteyz; 06-06-2008 at 06:13 PM.

  3. #3
    Moderator beerdart's Avatar
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    Compression on a gauge is not actual compression of the cylinder under fire. The gauge that you use has volume depending on where the gauge valve is. The cc of the chamber is changed when you install the gauge.

  4. #4
    anybody?

  5. #5
    Moderator beerdart's Avatar
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    Wash looks lean..

  6. #6
    how much do you think I should turn the highs out. I am 1 1/2 out now and 1 out on lows. It loads up kinda bad if idling for awhile. Im running 125 mains 110 pilots 1.5 ns 95 gram spring accel pumps blocked off and choke plates removed. mixing 36:1

  7. #7
    Moderator beerdart's Avatar
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    1/4 should be good just keep an eye on the plugs and the wash.

  8. #8
    should the lows be left alone? will it always load up idling around?

  9. #9
    also was gonna go do some wave jumping next weekend and was gonna throw the stock airbox on for saftey what should I do jetting wise compared with the r&d power plenum. Also I was only gonna stick the box that bolts to the carbs on with NO metal screen and leave the rest of that crap off. Will that prevent water intrusion better than the r&d. Just dont want the motor to go BOOM.

  10. #10
    also would it be worth maybe running to sears to pick up a new comp. tester. The one I have is a lisle and I bought it for like 30$ so maybe its off alittle. I saw sears had some craftsman ones so I was thinking about going and picking one up. Also would the readings change from the motor is warm and cold. Which should I go with? Just wanna figure out why #3 was like 8psi lower than the front 2. It was like that from the time the motor was first put together. Any ideas?

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