VFR750 low compression in all cylinders

Discussion in '3rd & 4th Generation 1990-1997' started by Bubbles, Jan 26, 2012.

  1. Bubbles

    Bubbles New Member

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    Hi everyone, I'm new to this Forum and I'm looking for some advice on VFR engines. I have a 95 VFR750 which is my first Bike and i had it for about one and half years. The milage is about 35k and having a workshop now I decided to give it a good service. I started with checking the valve clearance which turned out to be ok according to the Haynes manual. Then I checked the cyclinder compression and I got around 9 bar in each cyclnder which is suppose to be 14bar +-2. I made sure the engine was hot and the throttle was fully opened when I did it. I squirted a bit of oil in each cylinder but the reading didn't change much ( a bit closer to 9.5bar). The pressure builds up quickly but doesn't go any further. The exhaust fumes are free of oil and water (checked it with a piece of white paper against the end can). About a year ago I had a bit too much oil in it but I changed that after a month or two. I did notice a bit of oil on the thread of some spark plugs but the plugs themselves where free from any oil and other residues. I guess it only leaves the valves and looks like I need to do a down leak test. Did anyone had similar experience or some ideas what could be the cause as the loss of compression is the same in all 4 cylinders. Any advice/tips and tricks would be great. Thank you
     


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  2. tinkerinWstuff

    tinkerinWstuff Administrator Staff Member

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    as long as they are within 10% of each other and the engine runs well, I wouldn't be concerned about the reading.

    sounds like you just checked it because you have a new shop and not because there was any noticeable change in the engine over time.

    Could just be that you have a bad gauge for that matter.

    The likelihood of having 16 valves all leaking the same amount is pretty slim.

    ride it like you stole it and don't worry IMO
     


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  3. TOE CUTTER

    TOE CUTTER Mullet Man

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    +1, if it ain't broke don't fix it.
     


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  4. Bubbles

    Bubbles New Member

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    Thank you for your quick reply. Partly is the case of having a new workshop and wanting to play :) but I also had the impression that the engine lost a bit power. Nevertheless it is my first bike and I could be wrong and worry too much which is probably the case. I think I'll check the valve clearance and timing again and leave it with that. I di buy a new compression tester but it was a cheap one. Thanks again for you thoughts.
     


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