6th Gen Getting Hard to Cold Start in Colder Weather

Discussion in 'Mechanics Garage' started by Scott45, Jan 11, 2020.

  1. Scott45

    Scott45 New Member

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    I've had this 2008 model for just about 4 months now and the understanding with the wife is that I ride it year round. That part isn't a problem yet but what is getting to be a problem is the fact that the bike isn't starting right up like it used to in warm weather.

    I put the switch to run, wait for the FI pump to stop, hit the starter, and listen to it turn over (powerfully - good battery) but not catch for about 3 seconds or so. I release the starter, wait another 3 -4 seconds, and hit the starter again. It will halfway catch for second but won't get going until after I keep holding the starter down for another couple seconds. Once running it functions normally.

    This started with the colder weather (sub 40 degrees F) and after riding I can turn the bike off, wait 5 seconds and it'll start back up instantly. When the first really cold morning got here (17F) I don't recall having this problem at all. It has only been in the few weeks or so.

    So far my troubleshooting has been limited to adding a can of SeaFoam to a fresh tank of non-Ethanol 86 octane. Made no difference.

    Thoughts on what I could be facing here?
     
  2. GreginDenver

    GreginDenver New Member

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    Your bike, being a 2008 year model, is going on 12 years old now. You say you've only owned the bike for 4 months so it is "new to you".

    Do you know if the prior owner did anything to maintain the bike? Or did he just ride it until the "maintenance honeymoon" was over then sold it off?

    There are two types of Honda owners: One type sees maintenance as a necessary thing that has to be done (these are the "wrench turners"), the other type chooses to believe in an almost religious way that "Honda motorcycles don't need maintenance".
     
  3. GreginDenver

    GreginDenver New Member

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    There's a laundry list of possibilities, some are simple to check and correct, others require work, time and some money (gasp!).

    The list of possible causes is pretty long, and it's also possible that your problem could be the result of a combination of more than one causes (especially if the bike hasn't received much maintenance/love during its life).

    Here's one possibility: it has been documented here on the forum that mice really like the design of the VFR and especially its airbox. As cold weather settles in they will build a nest inside the airbox, up on top of the filter element. This restricts airflow and makes the bike hard to start and the bike will also be down on power (which is sometimes hard for the owner to notice). We (here on the forum) have seen many pictures of this situation.

    Here's another: Tight intake valves cause poor cold weather starting characteristics. If your VFR's valves have never been adjusted this might be a contributing factor to your cold weather starting problems. Lots of VTEC VFR800s never get valve adjustments because of the expense (when the job is done at a dealership) or because it's a relatively complex job for a do-it-yourself-er.

    Another possibility: the cold start Fast Idle Wax-Core Unit on your bike has aged and isn't moving as far as it used to do. If the Wax-Core Unit isn't opening the Starter Valves far enough the bike would be hard to start.

    Here's another easy-ish one: how old are the spark plugs? maybe the bike just needs some nice new spark plugs. And (for-the-love-of-God) if you're going to replace the spark plugs, install the Honda VFR800 Service Manual recommended brand/type.
     
    Last edited: Jan 11, 2020
  4. raYzerman

    raYzerman Insider

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    +1 on what Greg says... do the easy stuff first, fresh plugs and air filter..... see if it improves. Sounds like the fuel you're using is OK. Maybe needs a few good runs with Seafoam in it.
    Valve check when you get to it, I'm wading into this right now myself on this new-to-me VFR.... it's never been done in 60 k miles, and the bike is running fine. Air filter looks like the original (ugh!) but may not be.
    All that said, it's not unusual for a bike to take a bit longer to start when it gets down to those temps, but FI bikes usually fire right up regardless.
     
  5. Scott45

    Scott45 New Member

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    Greg - Since the bike came from auction I've no written maintenance history to work with unfortunately. There was under 7k miles when I got it and the tires, though with decent tread, were old (based on the date stamp) and cracking due to dry rot. They're of course replaced now. Everything I've see about the bike is bone stock save for a fender eliminator kit.

    The bike is a daily driver and I checked the airbox for nests after I got it home (4 months ago) and there were none. I'll check again though just to be sure. I'll also order a new air filter even though the old one looked fine to me when I glanced at it.

    I've never done anything with the valves and wouldn't dream of doing it myself. No dealers near here but we have some good local guys that can probably handle the job. Got a rough guess of what a valve job runs?

    Never heard of the "fast idle wax core unit" so I'll be doing some research on that. Hopefully it's something I can replace without too much trouble.

    Wouldn't hurt to put new plugs in since I'd bet money it still has the originals. Guess I need to go ahead and splurge for an owners manual and Haynes manual while I'm at it. While I'm hoping and dreaming, perhaps the plugs are easily accessible.

    Rayzerman - I'll do plugs and air filter first but if the valves on yours are just causing problems at 60k miles it seems unlikely that this bike (having now only 7k miles) is having problems there.

    I'll report back after I handle the simple stuff. Thanks guys!
     
  6. raYzerman

    raYzerman Insider

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    OK, 7k miles.. won't be much history. That would rule out the valve check IMHO for many miles later, but check the air box/filter. Plugs MAY be OK but you're in there anyway.
    I'd venture to say the wax motor is OK if when it starts, it goes to the proper fast idle and drops to normal idle when it warms up.. but it does affect the starter valves.... a starter valve adjustment might be in order.
    Cold start issues are more about mixture, temperature and condition of plugs. A dirty air filter shouldn't cause starting issues, unless of course you have a rats nest in it.
     
  7. GreginDenver

    GreginDenver New Member

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    There is a very good electronic version of the 6th Gen VFR800 Service Manual available for free download right here on the VFRWorld website (or maybe it's over on the VFRDiscussion website, I can't remember which one).
     
  8. Scott45

    Scott45 New Member

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    While looking up the fast idle wax unit I remembered that my idle speed seems higher than it should be, even when warm. That may be part of the problem but I'm not totally sure how that thing works so maybe not.
     
  9. GreginDenver

    GreginDenver New Member

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    Well, there are 3 factors at work in this: 1. How is the Throttle Stop Screw set (Page 3-17 in the Service Manual), 2. Are the Starter Valves properly synchronized? (begins on Page 5-75 in the Service Manual) and 3. Does the Fast Idle Wax Unit work properly, this is affected by 2 things: the condition of the Wax Core and the condition of the very small coolant supply line that is plumbed onto the Fast Idle Wax Unit.

    You may be dealing with one thing that is the true cause of your hard cold-starting and something else that is a Dumb-Prior-Owner induced side effect. If the prior owner was beginning to experience hard cold-starting issues he might have not known what was causing it (like out-of-adjustment Starter Valves) so he simply grabbed the Throttle Stop Screw and twisted it to increase airflow. And maybe messing with the Throttle Stop Screw did help the prior owner a little bit with the cold starting problem, but when the bike warms up the higher setting of the Throttle Stop Screw results in a too-high idle engine RPM speed.
     
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  10. Terry Smith

    Terry Smith Member

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    Link for the service manual: https://www.vfrdiscussion.com/index...load&csrfKey=a55467a5b2b39bb4343398e58e49c256

    I think starting with new plugs is a good idea, you might also need to take a general look at the connectors in the wiring harness in case you have a bit of corrosion that is causing weaker sparks than expected. At that low mileage I agree that I would ignore the valves and compression and also assume that the rubber inlet boots are in good shape.

    You should be able to visually check the wax unit function but would need to take the airbox off to do that. Basically the idle speed of these bikes is set by the volume of air flowing through the starter valves; open the starter valves more, you get more airflow and a higher idle. The starter valves are held open via linkages by the wax unit which is (or should be) in contact with the coolant flowing around the cylinder block; as the coolant heats up the wax unit changes length and when properly warmed up the starter valves will rest fully on the idle adjuster screw. The wax unit functions in the same way as the coolant thermostat, the wax inside expands when heated to mechanically move a related part, in this case the starter valves.

    If a wax unit failed in the hot position, the cold start idle will be very poor (too low/starter valves not opened). If the wax unit fails in the cold position, you'd have a horrible high hot idle. If the cooolant hoses block, you get normal cold-start elevated revs, some high revs when warm, but eventually the wax unit heats due to heat soak in the engine bay and the revs drop back.
     
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