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Bike lurches me forward

Discussion in 'Technical and Troubleshooting Torque' started by RedWings01, May 11, 2016.

  1. Hi,

    Recently I felt that my bike lurches me forward a lot when I roll off the throttle. I have no idea what is causing this but I thought it was my front brakes. Cleaned them and spun the wheel. Rotates like it should with no drag. Am I imagining this? Could there be any other issue that may cause a lurch forward when rolling of throttle? It is much more noticeable on lower gears.

    Bike: VTR250

  2. Some "jerking" is normal due to engine braking and this will be more prominent in lower gears. However I am assuming you mean more than usual.

    How is chain adjustment? That can cause jerking.
    • Agree Agree x 1
  3. Yeah it feels like its jerking a bit more than usual. Chain was adjusted recently. Maybe its my own imagination. First gear seems a lot more jerky than I remember.
  4. Did you adjust the chain or someone else? Check it again to be sure

    You haven't said how old bike (or chain) is but as chains get older they go out of adjustment quicker.
  5. chopping the throttle is a bad habit to develop and the cause of many riding issues. watch the YT video link as it may assist.

    • Like Like x 2
  6. chain slack, cush drive slack, wrist slack... fix those and even if you do get all choppy, it shouldn't feel as harsh
    • Agree Agree x 2
  7. The only mechanical problem likely to cause increased engine braking intensity is when it siezes, and then you will only experience it once ;)

    Stop revving the fcuk out of it in low gears and chopping the throttle suddenly and the problem goes away.
    • Funny Funny x 2
  8. Ok guys I will stop chppping the throttle lol. My chain is pretty old I assume, was in bad condition when I bought my bike. I'll probably replace it too.
  9. Right just rode this morning and I swear its the brakes. When I start in the cold I notice lots of drag in the front brakes. Does this have anything to do with fluid? It feels like it gets better as it warms up.

  10. It's more typical for contaminated fluid to make the lever spongy, although I wouldn't rule it out.
    Check the condition of the bore and seals of the brake pistons. You may need to call in a pro if you're not sure.
    • Agree Agree x 1
  11. Could there be a sticky piston in the caliper ? The bike is 2001 ? so after 15 years the brakes may well have been neglected.
  12. How can I check if its stuck? The problem started as the weather started gettint cooler.
  13. I don't recommend people messing with brakes unless they know exactly what they're doing. You need to be able to re-assemble everything properly at the right torque settings and brake fluid (I think Honda mainly use DOT4 fluid) is quite slippery, (similar chemistry to antifreeze) so you don't want it leaking anywhere near your front tyre. You don't want to spill it on your paint work either, it degrades paint pretty quickly. Feck it up and you are in for a world of hurt.

    I would check the service history of the bike first and see what has been done with the brakes. Over 15 years they should have had fresh fluid a number of times and probably a few sets of pads. A competent mechanic would be checking these sorts of issues while they're doing the pads and replacing the fluid, but mechanics vary in their diligence and home mechanics vary even more. If the brakes are binding you may get some physical clues, they get hot for a start, so you can look for discolored or warped discs (check them with a steel ruler to see if they're flat). Excessive and uneven wear on the pads. If one piston is sticking you may have one end of the pad far more worn than the other. Warped discs may feel a bit like ABS, you may feel pulsing at the lever as the piston moves in and out to accommodate the deformation of the disc. The bike may shudder when braking. You may be able to smell the friction material burning.

    In order to check them you'd have to pull off the caliper and see if the piston moves freely. As titustitus said it could be deterioration or contamination of the piston or bore (that's the cylinder that it slides through) or the rubber seal that stops the brake fluid from leaking out. To check the piston surface, bore and seal you really need to remove the piston entirely, which will usually require refilling the system, bleeding it and replacing the seals. You should be able to gently push the piston back in a bit if it isn't seized. They should slide out easily when the brake lever is squeezed but unless you're able to replace the fluid and bleed the system, you don't want the piston to come all the way out.
    • Like Like x 1
  14. Check your rear brake as well, it may be dragging.
    • Agree Agree x 1
  15. Will check when Im home but Im almost certain its the front brake as It lurches me foward like im pressing the front brake. I might just rebuild the caliper, any ideas on what I need? Was thinking the piston seals but what else? Thanks
  16. Download the service manual, that will give you all the details you need. Includes an exploded diagram of the brake calliper and also all the torque settings you will need to know. Bikes use so much alloy that correct torque settings are critical.
    • Agree Agree x 1
  17. This may sound obvious but if you're pulling them apart anyway, it might be worth having some new pads to stick on while you're in there anyway. Having the kit you need, tools, parts, seals, fresh fluid and so on before you start is good too obviously.
  18. #18 RedWings01, May 12, 2016
    Last edited by a moderator: May 18, 2016
    Ok will do. Thanks for your help.

    Yeah, will be ordering them soon. I just want to do everything instead of trying to figure out what is wrong.
  19. does it do the same thing when you roll at constant speed, then pull in the clutch?

    (on a deserted road) when you pull in clutch, kill the engine, roll along and listen to hear if front or
    rear brake is dragging
    • Agree Agree x 2
  20. Not really. It feels like it isnt dragging at all. The problem is, it sometimes drags then sometimes doesn't. When rolling down the driveway today, I noticed that it rolled much slower than before but maybe it rolls better next time I do it. This is why I think its related to cold weather as it is more prone during the cold. When the bikes been warmed up for a while and I've been riding for a bit, it seems like it works O.K. Maybe the callipers seize up because of the cold? Or something like that. But I mean it doesn't even get that cold here (10 degrees). I def notice the difference when pushing the bike last night and this after noon parking in the garage. Seems bloody unusual to me so I was going to just put new fluids, bleed the brakes, new pads, clean the caliper out thoroughly. Hopefully that should fix the issues.

    About the rear brake, I can't hear anything noticeable. Nothing that I see or feel tell me its the rear brake as If I'm riding down a hill and clutch in (when it does drag) it lurches me forward enough that sometimes I slide forward in my seat if I don't keep my knees tightly on the tank.

    What I did notice was when I took it to my mates house and put it on the stand, I rotated the front wheel it moved O.K but when I pressed the brake a few times I noticed that it would rotate maybe 3/4 more than before.