TnT899 cylinder compression
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Thread: TnT899 cylinder compression

  1. #1
    Member Adonis's Avatar
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    Question TnT899 cylinder compression

    Hi guys!
    anybody know what the cylinder compression is for the TNT 899? I get 130 psi on cylinders 1 and 2 (right and middle) and 93 psi on 3 (cold tested with a pressure gauge). The engine hardly exceeds 7500 rpm (190 km/h), could it be related to low compression or maybe it's time for a valve adjustment?
    Thanks

  2. #2
    GBo
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    That’s not good try it again with a little oil down the plug hole if it increases it could be rings. But that’s a big variation.

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    Senior Member Engenia's Avatar
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    Errol Kowald
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    #3 is an issue, but 130 psi isn't that great either. I'd be looking at > 150 for a high compression engine. Closer to 200 if you've built a really good one with gapless rings and carefully lapped the valves

    You're better off doing a "leak-down" test though, as you can hear where the problem is.

    This video describes the procedure quite well, and at 5:00 explains how to interpret the information. Essentially, listen at the oil filler and if you hear air flow, it is the rings that are leaking. If at the inlet manifold, the inlet valves, exhaust manifold - exhaust valve, radiator bubbles - blown gasket.

    You don't have to buy a leak-down tester if you are handy at diy. They are simple. I made my own. There are plans on the net but I can post mine if you need it.
    hooroo, Errol www.engenia.com.au [136,351 km - and counting .....]

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    Member Adonis's Avatar
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    thanks for helping guys, I appreciate it!
    Errol's details are very useful, as always.
    I will perform the leak-down test and I'll be back.

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    Member Adonis's Avatar
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    I did a new compression test, this time at 55 ° C, according to the dashboard, and the values ​​are now: 150-155 psi on cylinders 1 and 2 and 163 on 3
    Spark plugs look good, since I adjusted a less rich mixture last time.
    I suppose I would obtain higher values if I could perform the test at the working temperature, so it may not be necessary to visit the workshop (180 km away ...).
    TnT899 cylinder compression-20200208_124313.jpgTnT899 cylinder compression-20200208_124355.jpg

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    Member Adonis's Avatar
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    This is the result of the sync test:
    TnT899 cylinder compression-20200209_121834.jpg
    cylinders seem synchronized and the bike is running well.

    Even so, I cannot exceed 190 km / h

  8. #7
    GBo
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    Hmm should do a lot more than that. Does it rev into the red ok? Any misfires? Have you checked if it might be too much the other way and too weak.

  9. #8
    No good with spanners.... fredzedex's Avatar
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    simon stokes
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    It’s not a Euro restricted TNT is it?

    The one I imported from France was, although it was only a mechanical stop on the fuel injector butterfly rail. Now removed

    Fred


    here's to another trouble free year of Benelli riding

    TNT 899 (2013)
    Tornado 900(sold)
    MV F4 1000 (2010)
    TNT 899s (sold)
    Tornado 1130 (sold)
    Aprilia Dorsoduro 750.(sold)

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    Member Adonis's Avatar
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    The engine does not rev above 7500 rpm.
    As for the restriction, I haven't detected a mechanical one.
    I also reinstalled the map a few months ago...

  11. #10
    Senior Member ianh's Avatar
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    Worth checking the flap in the exhaust valve(exup type thing) . Mine is wired open for better performance, but when the wire holding it open snapped it allowed the flap to move around in the pipe, causing poor running above 6k. Worth a look anyway.
    Pre Benelli, ZR50SL, RS100, BMW R50/5, RD400, CB350K4, GPZ550, CB900, 750 KATANA, GSXR750, FIREBLADE, TL1000S, 955i Daytona, GSXR 1100L, GSXR1000K6.....

    Now; 2003 900 Tornado, 2008 900 Tornado, 2009 CR 1130, 2010 1130 Tornado...and the diesels...Ducati 848 for when four italians are not enough... a 750 srad ....when 5 italians are too many.......and now an '81 Katana......for those mid life crisis days....

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