4th Gen Running Rich/Overheating? How to diagnose?

Discussion in 'Mechanics Garage' started by bullit199, Jul 11, 2016.

  1. bullit199

    bullit199 New Member

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    Hi everyone,

    I have a 4th gen VFR that is having issues occasionally when it's really hot outside. If I have to sit at a few intersections the bike really doesn't like it. I do have a manual switch to turn the fan on but that doesn't seem to be enough. The bike will start to heat up past the mid point on the gauge and will sputter out and stall as soon as I give it gas staring in 1st gear. I'm not really sure if this is simply a heat issue (ambient temperatures were over 106) or if I'm running rich or lean. I also have to report that I did flood the engine about a week ago accidentally when I rode with the choke on for about 40 miles (newbie mistake for sure and you better believe it won't happen again!). I had to clear the flooded engine by starting it with the throttle full open as the owner manual instructed. I wonder if I might have fouled the spark plugs but I doubt it. When it's cool outside the bike seems to run just fine. No issues with startup or pulling out with a cold engine. What advice do you have about diagnosing this issue? I'd rather be confident riding in the heat but I'd like to hear if anyone else has experienced this too.

    Thanks,

    Bullit199
     
  2. RVFR

    RVFR Member

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    106! That's getting up there temp wise, My experience back then was I had no issues when on a ride in that same heat , so two things, maybe three, one, thermostat, but then it would heat up like what you say no matter the heat outside, just soon here vs. later. You say you have a manual fan switch? you're sure the fan is on, see it, hear it? From that being the vfr is a man made object and everything man made is subject to some sort of failure at one time or anther. Could be you have some issues with the radiator. also a good flush may help too. just saying.
     
  3. 01ragtop

    01ragtop Member

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    I've had similar issues with another make. Depending on how the bike has been maintained, it might be time to flush the radiator. The stuttering/flooding issue could be a rich condition that is only exacerbated by the heat. In my case, the needle valves on the floats would leak by when the bike got hot.

    Not saying this is your issue, but just some thoughts.
     
  4. V4toTour

    V4toTour New Member

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    I'll second the radiator flush, especially on a bike up there in age. 4th gen you're talking about bikes around 20 years old. It's not expensive to have done. Last time I had a bike running hotter than normal, I pulled the radiator and used a borescope to inspect the inlet side passages. They were partially plugged up with scale. Took it to a radiator shop and had them power flush and pressure test. I don't think most places do the hot dip anymore due to the chemicals involved.
     
  5. squirrelman

    squirrelman Member

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    Could also be a low coolant level. Dija check under the radiator cap when the bike is cool ?? It should be right up to the top.
     
  6. karazy

    karazy New Member

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    Once you have confirmed that the fan is working and the coolant level is good, you may want to check your charging system. If it is low, the fan will be too much load for it. Check it with the fan off and running.
     
  7. squirrelman

    squirrelman Member

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    It's usually a good idea to simply replace the radiator cAP b4 any troubleshooting as it may have a cracked seal or weak spring and not holding pressure. It might LOOK fine but be defective, and they never last more than a few years. :eagerness:
     
  8. bullit199

    bullit199 New Member

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    Thanks for the suggestions everyone. I did a full coolant flush two days ago. The old stuff was dirty and very dark green. I did an hour long ride and temps seemed to stay lower. However, I stopped for breakfast and when I left I let it warm up for 1 minute and when I pulled out I gave it gas and it sputtered out. Instead of merging with a bunch of traffic I went down into a neighborhood and opened up the throttle by going up to 8000 rpm range.

    This seems to indicate I might be rich or lean. Any ideas?
     
    Last edited: Jul 17, 2016
  9. RVFR

    RVFR Member

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    On this after breakfast start, was it a cold? like sat all night? or did you have it out prior, came back in ate, then went back out? so in that it was warm, so shouldn't have needed the choke. I'd be looking that over. hard to tell here being it's a hear it and get a feel how it acts thing. Iwas going to throw it out also maybe a fuel pump, but then you get it going. so in this I'd need to see this in person.. sorry.
     
  10. bullit199

    bullit199 New Member

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    No, it was right after the hour long ride. It sat for like 30 minutes while I ate. Sorry if that added confusion. I'm just recapping what happened yesterday. Maybe I'll shoot a video of it acting up sometime. It's just hard, I have an iPhone and I ride with gloves so it would be tricky to capture the riding part.
     
  11. squirrelman

    squirrelman Member

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    Rich or lean ?? Examine your sparkplugs.
     
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