'06 800 cold starting weird behaviour...

Discussion in '6th Generation 2002-2013' started by Sam99, Feb 14, 2017.

  1. Sam99

    Sam99 New Member

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  2. Expvet

    Expvet Member

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    I had a similar issue on my 06 and while adjusting the throttle bodies found a vacuum hose with a small leak. Once I replaced it the idling returned to normal. If you can get a hold of a vacuum gauge check them (or have a mechanic check them). Going on 11 years old and high heat dries them out and small cracks are not uncommon.
     
  3. Sam99

    Sam99 New Member

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    Aha. Thank you. The hoses in the middle of the throttle body that run to the starter valves?
     
  4. Sam99

    Sam99 New Member

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    6.30pm this evening, 6 degrees C, having sat since 10.40am, I pressed the starter, straight to 2000 rpm, stayed there for 10 seconds, rose to 2500 rpm, stayed there till at running temperature. So it's intermittent now. Sigh.
     
  5. Sam99

    Sam99 New Member

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    Hi chaps, the other morning I disconnected the clutch switch and started up, revved immediately to 4500rpm without me touching the throttle. I reconnected the clutch switch, revs dropped immediately to 2500rpm. This morning, 6 degrees C the bike started, revs dropped to 900rpm, I gave it a little throttle to keep it going, (which it doesn't seem to enjoy, much) till the revs pick up to around 2500rpm... I put it in gear with the FIWU still doing its thing at 2000rpm and there was no rise in revs... aaargh!
     
  6. Sam99

    Sam99 New Member

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    I'm putting a new clutch switch on, see what happens... I've been doing 200 miles a day for the last three weeks, and it does seem to be starting better.
     
  7. Expvet

    Expvet Member

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    Sorry for the delay, just came back from vacation. Snaking around the throttle bodies (no need to remove them) are a series of vacuum hoses, most of which are joined via plastic T couplers. It was on one of these hoses that I found a few small barely noticeable splits in the rubber. Once I replaced it with the easy to find auto part store equivelant all problems were resolved and it now revs up during cold morning starts and settles down once the proper idle temperature is achieved.
     
  8. Sam99

    Sam99 New Member

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    Update! So I had a full service done. All fluids, clutch, brakes, oil and filter, coolant, fork oil. All valves checked and all spot on at 37k miles, and not checked before. Rear linkage dismantled and greased. Replaced thermostat with OEM. Swapped throttle bodies for an unmolested (fast idle wax unit as set in the factory, unadjusted, paint mark on the thread unbroken) secondhand complete assembly that I picked up on eBay. Now it runs perfectly. Started today at 1 degree C, didn’t stall. No more weird revving in gear at temps below 60 C. I don’t know what voodoo Honda apply but the dealer I bought it from (Dobles) were unable to fine tune it, and gave me some BS about “they all do that sir”.
    £550 to do all the above by my local mechanic. Now I trust my VFR800.
     
  9. OCLandspeeder

    OCLandspeeder Member

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    This sounds all too familiar for me. I realize this response is too late to help you but here goes anyway....

    I went through this whole saga of having a high idle and at first I worked on and replaced a few things and none worked. The issues began AFTER I did a Starter Valve Synchronization. As another knowledgeable VFR owner told me, I had a "Runaway Idle" issue. This issues is usually caused by excess air entering your cylinders from the Starter Valves and/or downstream of it. The vacuum hoses leading to the MAP sensor (located below each throttle body) reads this extra air entering your throttle bodies, so it compensates by telling the MAP sensor to increase the amount of fuel. This in turn raises your idle. This is why your spark plugs look "wet". They are getting way too much fuel at idle.

    In my case, the bike would start and rev up to 2,500 RPM, then VERY slowly come back down to a still-too-high 1,800 RPM at full operating temperature. Sometimes when the bike got really hot the idle dropped to 1,600 RPM but that was still too high. I replaced ALL the vacuum hoses to the Starter Valves with no effect. I replaced the Throttle Body air seal boots with new boots with no effect. I replaced the MAP sensor with no effect. I was quickly running out of options until I carefully looked at the Starter Valve mechanism, specifically, the plate that the Wax Idle Unit pushes up against. There is one small bolt that adjusts how far the Idle Unit can push against that SV plate. It has a factory white paint on it to indicate "DO NOT ADJUST". I realized after staring at this mechanism that the Idle Unit adjuster screw allowed the Idle Unit to push the SV plate just enough to pull the Starter Valves slightly more open enough to raise the idle. So I loosened the Idle Unit bolt just a notch to allow it to release the plate and allow the starter valves to "close" fully to their natural position (when properly synchronized). Viola! Runaway idle fixed!

    My bike's idle is now back to a normal 1,200 RPM at full operating temp. When cold, it will rev up to 1,800 RPM but slowly drops down to normal as coolant temp rises.

    My suggestion to you is to first make sure all your Throttle Body Air Seal boot bolts are tight per factory spec. All 8 of them. You will need a very long screw driver and the airbox needs to be off the bike. Once you have verified these are tight, make sure all your vacuum hoses are secure & leak free. If the high idle persists, inspect the Idle Unit mechanism actuation against the Starter Valve plates. Make sure the Idle Unit is NOT pushing against the SV plate at full operating temperature. It should only push against that plate when engine is cold. If the Idle Unit is putting even a little pressure on that plate at full operating temp, the SV's are being forced open,which causes your high idle. If this is the case, adjust the Idle Unit adjusting screw just a tad to ease the pressure off the plate. Remember to do this at full operating temp so that you can verify the idle settles at 1,200 RPM. Also do NOT loosen that screw too far because you still want the Idle Unit to push against the plate when the engine is cold.

    Good luck. Don't let the dealership touch your bike anymore.
     
    A.M likes this.
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