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Clutch slip- VFR800

Discussion in 'Technical and Troubleshooting Torque' started by Dazzler, Apr 27, 2010.

  1. I have just experienced a strange clutch slippage for the second time in a week.
    Bike VFR800 non-VTec
    I always warm bike to 80 degrees before riding off. I take it easy for the first 5 minutes.

    Twice now, both at 5 min into a ride, I have given full throttle in third gear from @4,500rpm and the bike pulls away nicely, then at around 6,000rpm (where the power kicks in) the clutch begins to slip. At first I thought it was tyre slip on the damp road, but no, the clutch was slipping. On the second day when it happened, I knew it was clutch slip straight away, so backed off the throttle and resumed the ride at a more leisurely pace.

    A few minutes later I replicated the scenario and there was no slippage at all, in fact it didn't do it again all day, no matter how hard I tried.

    Oil is Motul 5100 (the best VFR oil) This isn't the problem.

    Is it time for a new clutch?

  2. Oil leak on the clutch plates? could explain the erratic nature of the problem.
  3. Wet clutch, sorry, panza, it's immersed in oil all the time. I'd be more looking at the clutch mechanism/master cylinder.
  4. I am with rc36 on this, start simple, and an inspection of the hydrolic clutch is easier then removing the clutch cover and diving in. Make sure the lever is correctly positioned and has some grease on the pivot pin. Then open the clutch fluid resevoiur up (it's brake fluid in there, so take the normal precautions and protect your paintwork!). Visually check the operation of the master cylinder (opening and closing), and if the fluid is old/yucky, replace it. I would also give the clutch slave cylinder a once over - this involves pulling off it and the front sprocket cover. If you want to give it a clean/internal inspection you will need to bleed the clutch dry first (I found out the hard way what happens when you don't do this last time I did this). Make sure the rod which runs from the clutch slave to the clutch itself is in good condition and not sticking. Then put everything back together.

    If you are not opening up the clutch slave cylinder it should take you less then 30 minutes. If you haven't done so in the last 12 months, bleed the clutch with some fresh brake fluid.
  5. Hmm, basically describes the same observation I made on my 5th gen ('98) almost 1 year ago. Did it a couple or three times, same section of road, 5 mins after heading home, cold weather. It was up for 175,000k service so figured maybe clutch time and raced out and bought a full kit. Subsequently couldnt replicate the event and nor could mechanic. He suspected wheel spin (road was slick and damp each time it happened) but I had my doubts as the rear remained stable.

    Anyway with the cause unknown the bike has gone on to 207,000km with no more slippage - go figure.
  6. Thanks for the ideas, guys.

    Well I went out today and sure enough first time I gave it heaps in third gear it pulled hard till 7,000rpm then the revs quickly increased to 10,000 without the corresponding increase in road speed. this was 10 minutes into the ride at normal temperature. I slowed again and tried it again, NO DICE??? wouldn't do it.

    Is it gonna kill me, probably not, but it's annoying knowing it's there.

    I may put in a set of clutch discs and maybe a new set of springs too.

    Took it to mechanic and he's a bit miffed as well. He also doesn't think it is a major worry at the mo. He could see nothing external that could be a problem. He did comment that the clutch lever was soft, may be springs afterall, hmmmm.

    Complete fluids change was done 8,000km ago. The brake and clutch fluids were xlnt even before the change.
  7. Seeing how it is random, I would look at the hydraulic system first. A sticking slave cylinder can cause this, as can a clutch pushrod (if it has one) and a master cylinder with a blocked relief port can also trap some line pressure in the system.
    Another thing to look at on higher mileage bikes is grooves worn into the clutch basket, sometimes one or two plates can "hang" on a groove and reduce clutch surface area.
    I don't think it's a major issue.

    Regards, Andrew.
  8. I would say a sticky slave cylinder to Daz , I reckon if the springs or plates where buggered then you would be able to replicate the scenario every time . Strip and cleaning the master and slave cylinder is much easier than doing a clutch basket.
    How many Ks you got on the VFR8 ? my 750 (now on its 3rd owner)has just clocked over 100,000 and everything cept the starter clutch is as per factory.
  9. I have to agree. Even if the bike has been sorely abused, the chance of the actual clutch itself being damaged is so slight as to be totally and, in every other way, inconceivable.

  10. G'day SirP, hope you're well. I know the master is clean as a whistle, but not 100% sure about slave, so may have a look on the w/e. The VFR is serviced thoroughly and regularly. It is only under max power in a tallish gear that this happens and it only happens once per day????? It's as if the slipping episode heats up the clutch plates or something and then it's not a problem. I googled it and found three other episodes but no answers.

    Andrew, if I'm going to check the push rod, I believe I need to drain the oil and remove the clutch cover, if I'm going that far then I'll do the friction plates and springs anyway. I will check the basket for grooves though. As far as I know, the clutch has not been abused and shouldn't be stuffed. Bike's done 84,000ks.

    Thanks again for your thoughts and helpful suggestions.
  11. No need to do all that just to check the push rod. It is hidden behind the clutch slave. It is possible to inspect without having brake fluid go everywhere, but it helps if you have done it before - so if you want to check to see if it is sticking or if it is the slave mechanism itself, you might want to drain the system of it's fluid first.
  12. I have a '99 VFR800 with just over 100,000 k's that has started to do this lately too. I replaced the fluid but didnt get any change.
    I then began to think if it was more of a psychological thing; as in when you are looking at the tacho trying to see it spin up as if it were slipping then you don't notice the sensation of speed when you hit powerband. So yeah, i figured it was just me not realising how fast i was going and forgetting how quickly the engine builds rpm when the power band.
    But after hearing a few other people saying their viffers have the same problem im not so sure any more.
    I'm curious to see what the result is.
  13. I gave the viffer an absolute caning last weekend, performed perfectly. . . .
    3rd, 4th & 5th gear 6,000rpm - then full throttle right through to 12,000rpm and no slip?

    I've ordered a new Barnett clutch and springs anyway and will do the change over next week. Check the rod at the same time. See if that makes a difference.
  14. I'd say it is early symptoms of the clutch on the way out. By getting it to slip the first time you heat it up and everything expands, so you can't replicate it until the bike is cold. It will get more pronounced over time.
  15. Well that was fun. Just finished clutch changeover.

    Purchased a Barnett high performance clutch (kevlar friction plates, drive plates, new springs and a clutch cover gasket) from the US. $250 delivered. Arrived in 8 days.

    Installed it today, my first time inside a motorcycle (been inside car engines heaps though). It took me three hours, I took my time.

    I checked the pushrod and there was no obvious signs or evidence of binding.
    There were some hot spots on some of the drive plates, but not significant.
    The friction plates looked glazed (probably normal though I suppose)
    The old springs were no where near as strong as the new Barnett springs.

    Assembled the new clutch assembly, fitted a new oil filter, refilled oil with new Motul 5100 (same as was in it previously), refitted fairings and fired her up. All good, no leaks.

    Took it for a ride and ABSOLUTELY NO SLIPPAGE. Felt quicker and stronger than ever too.

  16. I recon I saved $200 doing it myself.

    But moreover, it's the satisfaction of doing it myself, diagnosing, purchasing and then getting my hands dirty that is really making me grin tonight.