Difficult start after starter valves adjustmen

Discussion in '5th Generation 1998-2001' started by gips, Oct 21, 2019.

  1. gips

    gips New Member

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    Hello all,
    just wandering , if anyone who has done starter valve adjustments had a similar problem after that. So the issue is the following, the bike developed an irritating vibration that progressively became worse and worse to the point , when i decided i will do adjustment of the valves. So while doing it i actually noticed the problem was a bit different. Vacuum hose towards fuel regulator was half broken, so the regulator was not doing its job correctly and due to this there was a lean condition at low rpm, which caused this vibration. I have removed everything already, so i decided to do the adjustment anyway. I did it as per the manual. 1st and 2nd cylinder the same 3rd a bit less than 2nd and 4th a bit less than 3rd. Overall this made the bike even smoother than before the hose was broken. So i was happy and decided case closed. However next morning... its getting cold here now, i found out that the bike wont start as usual. Usually at this temperature .... around 7 degree Celsius the bike starts from 2nd to 3rd start at most. From adjustment onwards it takes between 4 and 5 starts until it can keep the rpm. So i am wondering, if anyone has any ideas here. Maybe some tested valve settings that will still prevent the bike to vibrate, but also make it start easily. I cannot do any testing myself as it will require disassembly adjustment and then assembly and waiting for next morning and so on...... the bike has no problems starting , when warm, or when not stayed cold overnight. Forgot to mention, i always start the bike with the lever fully open, except when warm, or almost warm :)
     
    Last edited: Oct 21, 2019
  2. bigbadbass

    bigbadbass New Member

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    mileage?...have actual valve clearances even been checked?
     
  3. bk94si

    bk94si Insider

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    I assume you replaced the vacuum hose?
     
  4. gips

    gips New Member

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    Should be ok, this engine is very low mileage. Same start with previous engine that blew. The previous one was at least 30k kms more. This one probably less than 10k, now 20, but nothing chnaged in the last 10k. 3-4 starts when very cold. ........ regulator hose was repaired of course. Now its like 5-6 starts after started valves adjustments......
     
  5. Terry Smith

    Terry Smith Member

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    At 105,000km my 99 5th gen always started easily with full "choke" and a single press of the button. I was very fastidious with the valve clearances and had fitted new inlet rubbers when I had the TBs off for thermostat and coolant hose work. I also had the PAIRS systems blanked off. Never replaced any vacuum hoses.

    I did find that it could occasionally stall out before fully warmed/choke off unless I had the idle turned up to 1400. Once warm it was rock solid.
     
  6. gips

    gips New Member

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    I will make a video, in the next days to show the exact behavior. But overall staring is now worse after starter valves adjustment. I own the bike for almost 4 years now and it was always difficult to start, when its cold outside. Old engine and new engine. They both started the same way, however i am using the same throttle bodies. The new engine came as a bare engine, so i used the old throttle bodies. Probably the problem is somewhere in the starter valves. I never disassembled them as i thought this behavior was normal :) It was always like that, so i assumed its normal, when temperatures are below 10 degrees, but now when it became worse i decided to look into it.
     
  7. gips

    gips New Member

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    Here is a short video of a cold start. Bike was in a garage and it was 14 C inside. As you can see it needed 3 runs on the starter. Before the adjustment at this temperature it started from 2nd run, sometimes first, if lucky.

    Y
     
  8. jfrahm

    jfrahm New Member

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    Have you tried cracking the throttle?
     
  9. gips

    gips New Member

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    Yes, i tried opening it a bit, but it didn't help. I will try opening it a bit more to see, if this will make any change.
     
  10. jfrahm

    jfrahm New Member

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    Given that you lost an engine I'd be curious about the fuel pump. Slow starting has been an indicator of a failing fuel pump for me. You could try letting it prime several times before cranking as an easy test.
     
  11. GreginDenver

    GreginDenver New Member

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    It's a fact that our 5th Gen VFR800s are now 20 years old.

    I don't know how long Honda intended the original fuel pump and fuel pressure regulator to last, but 20 years sounds like a pretty long life.
     
  12. gips

    gips New Member

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    Previous engine went, because of the small stock oil cooler. I have made a topic here, on that issue and the details are there, if anyone is interested. I have since upgraded the oil cooler to one double the size and this has solved all oil cooling problems whatsoever. Interesting idea, about the fuel pump. If its the culprit it will be the longest lasting dying pump, but i will check its pressure :) Today i asked a friend with the previous VFR to let me check his carbs. While measuring i noticed that the idle on his bike was very low according to my tacho reader..... well long story short, my tacho reader ground was half broken, hence the measurement was incorrect. Good thing he said that the rpm should be spot on despite his bike tacho showing less, same as my tool. So after fixing the ground and measuring his bike, where everything was fine i plugged it to mine and as expected the idle was too high like 1600rpm despite bike showing 1300. I was amazed how accurate my bike tacho was........ well it wasn't :p So it ended up my starter valves adjusment was incorrect. After changing the idle, starter valves were messed up, so i readjusted and tomorrow morning will report the situation. As for the fuel pumps on japanese cars, or bikes i am positive i have seen lots of cars with over 500K kilometers still on original fuel pumps, but those were 90s cars.......nowadays things are different, no overengineering anymore, only programmed obsolescence.
     
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  13. gips

    gips New Member

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    Not much progress, still hard start, when cold. Fuel pressure is good. Today it was 6C and it started from 5th run. Anyone know, what should be the resistance of the coolant temperature sensor at like 10C ? I looked at the manual, but there are only two values one for around 80 degrees and one for 120 degrees. Same question for the IAT sensor in the air filter box, couldn't find any info on this one.
     
  14. jfrahm

    jfrahm New Member

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    You could see if the plugs are wet when it has failed to start after a couple cranks.

    I have had a couple temp sensors fail, on an Audi and a Ford, and they both went open circuit. Indicating very cold.
     
  15. gips

    gips New Member

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    I was expecting the same, in case of a problem with a sensor, usually the failsafe value for temperature sensors in -40degree Celsius. Still i will try to find the output pins of those sensors at the ECU plugs and measure from there, to ensure the wiring is ok. Problem is that i can do testing the next morning, because as soon as the bike starts next start is normal.........so testing is done only, when the bike has stayed overnight. I have something in mind for the next test, but we will see.
     
  16. GreginDenver

    GreginDenver New Member

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    Have you looked at Chapter 21 of the manual? This is the chapter entitled, "Technical Features" and on pages 21-14 and 21-15 there are Ohm resistance graphs for both the ECT and the IAT sensors.
     
  17. GreginDenver

    GreginDenver New Member

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    The "fail-safe" temperatures for the ECT and IAT are listed in the manual, Chapter 21, on page 21-29.
     
  18. gips

    gips New Member

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    10x Greg. That will help, i see the graphs there, so for the sensors the expected resistance should be around 4Kohm. I see also the pinouts in that chapter, this will help me measure directly from the ECU plugs.
     
  19. GreginDenver

    GreginDenver New Member

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    It's funny that a lot of 5th Gen VFR owners haven't read VFR800 Service Manual Chapter 21 "Technical Features", but this chapter is some really good reading, every single paragraph of it. It's probably the best chapter I've ever read in any of the (many) motorcycle service manuals I've read through during my lifetime.

    This "Technical Features" chapter shows you (a Honda owner) just how hard the Honda Corp was trying in the late 1990s (it makes me feel nostalgic for the Honda I knew in my younger days) and it shows the quality engineering going on at Honda in those days. I think that part of this effort was Honda being a little worried about how the VFR800 would be received by the buying/riding public after several very successful generations of the VFR750. They (Honda) were making every effort to "get the word out" to their intended audience for the VFR800, which they envisioned as being a more mature type of owner/rider who, 1. would actually take the time to read the manual, and 2. would act as an "influencer" by spreading the word (in the late-'90s pre-social-media world).
     
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  20. gips

    gips New Member

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    Bad news here, everything from sensor side is intact. Resistance on sensors is correct depending on the temperature and also no problem with the cabling i measured directly from the ECU connector. Also checked for ECU faults everything is fine there too. I am getting out of ideas here. I guess i will simply repair the starter once in a while :)
     
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