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Terry

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Posts posted by Terry

  1. If the wax unit is not receiving coolant then it will keep the starter valves open more than you want when the rest of the engine is hot and give the excessive idle. Either an air lock or possibly the "cleaning" process has moved some crud in the small water hose and caused a blockage. My view is that a blockage is the most likely cause of a "wax unit failure" rather than any mechanical fault with the unit itself. 

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  2. Very thin, fuel-smelling oil and lots of it would indicate a leaking fuel injector. The tank is quite happy to gravity feed through the pump to the fuel rail, and if an injector is stuck open it can allow a quantity of fuel to drain into a cylinder, past the rings and into the crankcase. Good thing that you changed that out promptly, bad things can happen with so much fluid in the crankcase, and you likely have ejected some excess oil up to the airbox through the crankcase breather, which might explain a bit of smoke. Open the airbox up and take a look, a little oil mist is normal but not much in liquid form.

  3. I have done that myself on my 800; tried to install the pads while the calliper was mounted to the disc and managed to catch the edge of the pad spring during installation. Made for a weird brake as the spring would push the pad off the disc so there was lots of travel until the brake was pumped up fully. I would just straighten the pad spring out.

  4. 8 minutes ago, Lorne said:

    I've wanted to know, like forever, how a 6th gen would run if the VTEC was forced on. The manual is vague on the specifics but it seems that the ECM only cares about engine rpm and coolant temp to open or close a spool valve. But I am just daydreaming...

    I also wondered what would happen if you used the non-VTEC buckets and valves in the VTEC positions so 16 valve operation is constant. It appears the cam lobes are the same on both VTEC and not VTEC valves. Probably not worth the effort.

  5. 9 hours ago, tsmitty said:

    Did their motorcycle VTECs back then actuate a larger cam profile or valving?

    VTEC on the bikes activates 4 valves per cylinder at higher revs and 2 vavlves at lower revs. I think the earliest iteration had asplit forked rockers and a locking pin slid across to lock the two valves together. The VFR system stuck with the shim under bucket direct valve actuation of earlier models but the VTEC valves have special buckets that also use a locking pin activated by hydraulic pressure to connect to the valve stem. It sounds terrifying but clearly isn't as mechanically deadly as I would have thought.

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  6. I think you'll find there are some internal gearbox ratio differences between the 5th and the 6th. The crank is obviously different (gear vs chain sprocket for the cams) but AFAIK the bore and stroke are the same (so maybe rods and pistons?), and I assume the lower crankcase is too. I suspect the alternators are different. I know at least one person has swapped a 5th gen engine into the 6th frame so I presume the engne mounts are the same. 

     

    So aside from the crank, upper case/cylinders, heads, gearbox, alternator...its all the same? Probably doesn't leave much.

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  7. There's a balance involved between the starter valves, the idle stop screw and the wax unit nut. If you mess with one, you may mess up the other inadvertantly.

     

    Another member unwisely messed with the "unadjustable" starter valve screw (#4?) when synching the throttle bodies and closed those down more than they should be (but they were all nicely in balance 🙂). That resulted in the idle stop screw having to be wound in in much more than usual to get the warm idle correct to hold the starter valves open enough. And that resulted in the starter valve opening mechanism being held unnaturally open when the engine was cold to the point where the wax unit wasn't adding any cold opening to the SVs at all. Which means the cold start idle speed was unpleasantly low.

     

    If you can verify that the wax unit is changing it's length as the coolant temperature is changing but just not by enough to lift the SVs open when cold, then I would have a crack at changing the unadjustable nut, but at the very least mark the "factory" position before you start so if/when it all goes tits-up, you can return to the original setting.

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  8. 22 minutes ago, weerab said:

    Thank you Terry. Didn't know that. I noticed today when I put the kick stand down whilst in first, it cut off. Makes sense now

    The oil leak is quite impressive but also looks to have been ongoing for a while so probably not major, just persistant. I would start looking at the oil filter in that area, the other spot would be the cam cover gaskets; these can fall out of place when being refitted, or the half-moons didn't get any sealant as they should, or the gasket might not be clamped enough to seal. Don't be tempted just to crank more torque onto the hold-down bolts for these, they thread into the head casting and that easily snaps. You might need to replace the rubber washers under the hold-down bolts as these compress with age and don't apply enough clamping force to the gasket. Another possibility in the same area is the gasket around the spark plug tunnel  if that is not seated properly, oil can leak into the plug well and then out of drains under the heads. Not sure there is any other common oil leak point, but given you are in the UK with salted roads, corrosion on the oil cooler lines is something to consider. 

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  9. I don't recall hearing of any issues with the CB750 Hornet that was recently released with the same motor. Maybe your "interesting" climate has had an effect on a stationary bike engine that has not seen any running? I was thinking that if you cooled the system down a lot that would pull extra coolant out of the reservoir, and then when "normal" temperatures were applied the coolant expands and pressurises the system but not with the engine running and the ceramic seal wetted up? I don't live anywhere that cold so this is pure speculation on my part.

  10. 23 hours ago, Skids said:

    What, blow with my lips? 🤔

    Yep, the same way you blow up a bus. A more delicate soul might employ a compressed air line but honestly, if you are that risk-averse then motorcycling may not be for you.  

    • Haha 1
  11. On 1/26/2024 at 12:22 AM, toreckman said:

    Does flushing the cooling system out, resolve this usually? Or more serious work required?

    You may need to find where the small coolant hoses branch off and blow through there. 
     

    Wax units are very common on FI bikes prior to RBW throttles and will be found on loads of bikes. My 2005 ST1300 has one and that model was produced from o2 to 2012. The subsequent VFR1200 moved to RBW and relies on the ECM and the throttle stepper motors. 

  12. As a suggestion, you may have a blockage in the thin water tubes that lead to/from the wax unit. This means the wax unit does not see the high water temps and so keeps the idle high even when the coolant is hot. Eventually heat soak from the engine should allow the idle to drop but it might take a while. If you’re lucky you maybe able to blow the blockage clear without major surgery. 
     

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  13. 4 hours ago, bmart said:

    Is the conversion in the forum someplace? My wax is waxing just fine, but there are a lot of failures reported. I'd like to have a backup plan!

    I suspect the majority of failures are blockages in the water hoses leading to/from the WU that prevent it from chasing the idle down promptly as the water heats up.

  14. That looks like a label that belongs on any coolant concentrate based primarily on ethylene glycol.

     

    Did you know that water will boil at 102C even with a decent working radiator cap that holds 1.1 Bar? That is awfully close to the fan cycling temperature, so it seems extremely likely that you could start boiling the coolant as soon as you get slowed in traffic, if you used pure water. Boiling creates steam and that blows gas through the coolant reservoir and pukes out the contents. I don't think I would ever use straight water in my bike. 

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  15. 1 hour ago, Mohawk said:

    Not really required. I added temp sensors to the cooler lines & the VFR does not get that hot to worry about. The cooling system can get warm, but not too hot if everything works as it should. A simple tip for anyone in a warm

    environment is to reduce the anti-freeze percentage, as it is a poor coolant & distilled water is an excellent one ! In UK summer temps 20-35c mine runs @ 75-84c when moving. 

    While I agree with the comment in principle (which I would restate as the specific heat of ethylene glycol is half that of water, hence it takes less energy to raise a water-glycol mixture by a degree than pure water) there are other beneficial effects from the presence of glycol, namely it reduces the freezing point of the mixture so makes it less likely for the liquid to freeze (and expand and cause mechanical damage) while the bike is parked up, and it increases the boiling point so the cooling system can still operate at higher temperatures without spewing steam and coolant out of the breather. The mixed coolants also provide corrosion resistance.

     

    I stick to the recommended 50:50 mixture recommend by Big H. My '99 also runs happily through a New Zealand summer at around 78°C under all throttle conditions as long as there is good radiator airflow. My opinion is that the limitation of the VFR cooling system is more likely to be the rate of heat transfer from the hot surface of the radiator to the air than the rate of heat absorption from the hot engine to the coolant, hence the coolant used won't actually affect the running temperature of the bike. Using pure water will increase the heat-up time from cold, and will slow the rate of rise when the bike is stuck in traffic, but won't actually change the peak temperature that is ultimately reached. YMMV.

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  16. The bars are unique to the VFR800 98-01 years based on the part number cross-reference. You definitely can't use any off the 2002 onwards as they have larger diameter (43mm) forks. An earlier year (88-97) VFR will fit but the locating peg (into the triple clamp) will probably need to be removed and the locating holes for the switch pods may be differently located. 

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