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Thread: 1984 R65 with Dellorto PHF 32 guzzling gas

  1. #1
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    Aug 2012
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    1984 R65 with Dellorto PHF 32 guzzling gas

    I bought a 1984 R65 used and it came with Dellorto PHF 32s (aftermarket). The previous owner tapped them for VTO ports, so I balanced them at idle and at 3,000 rpm. In my mind, the bike seems to run like a top. No sputtering, backfiring, plenty of power.

    However, I hit reserve at 125 miles! I was expecting to get closer to 200 miles from a full tank.

    Possible causes:

    Stuck brake, etc - it doesn't seem like the bike is fighting rolling resistance
    Carburation issues - needle jet on wrong setting, maybe wrong main jet size
    Possible exhaust leak - The first time I rode the bike I left it on the side stand and saw some smoke coming from the left header/exhaust area. Sometimes at night I see what looks like thin wisps of white smoke in front of my headlight.

    I was thinking of starting with adjusting the needle setting to run leaner. In the summer in DC I feel like the bike is a bit too eager to start up. Any guides to actually make this adjustment on a Dellorto PHF out there? Most of what I find is kind of general information on these carbs.

  2. #2
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    Jan 2006
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    Wisconsin and Florida
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    You need to determine how much gas you use between full and reserve

    Starting with a full tank see how much drains into a container with the fuel tap in the run (handle straight down) position and then calculate your miles/gallon - measure with a glass household cook's measuring cup how much went into the container as you put it back one careful cup at a time

    I don't know about 84 but my 80 R65 has only one gas tap and you never get to use the gas on the right side of the tank unless you throw the bike over to the left to make the gas slosh over to the fuel tap side

    My 1980 R65 in fair and somewhat abused and neglected condition gets 50mpg at 55 and about 45mpg at 65-70 with the air to head system removed/defeated pushing a plexstar II fairing

    Regardless of the tank spec - what you get to use can only be determined by measuring - variable tap straw possibilities from PO make a big difference

    You cannot rely on the gas pump readings on fillup - seldom very accurate and often fraudlent manipulation is possible

  3. #3
    Registered User lkchris's Avatar
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    Mar 2003
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    Albuquerque, NM
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    How do spark plugs look?
    Kent Christensen
    21482
    '12 R1200RT, '02 R1100S, '84 R80G/S

  4. #4
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    Aug 2012
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    6
    They looked dark brown, but not sooty. I found it amazingly easily to move the notch on the needles from the most rich setting to the middle setting. Needles did not appear worn. After riding aggressively but safely and legally for about 20', I pulled the plugs and they looked light brown with a little touch of white.

    The choke operated more within my expectations and I feel like I was able to get a lot more out of the lower gears. I typically was feeling like I couldn't get out of 1st gear fast enough and 2nd gear wasn't tall enough for 25-30 mph roads, but now they feel much more useable.

    Finally, still seeing some smoke in front of my headlight... I think this is a combination of an exhaust issue and the previous owning topping up the oil level too high. I'll need to investigate further...

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