Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Jerking throttle

Discussion in 'New Riders and Riding Tips' at netrider.net.au started by d_n2blue, Mar 18, 2016.

Tags:
  1. Hi Guys,

    As a new rider I am finding it a bit difficult in some situations to be smooth on the throttle especially at low speeds. A lot of the time I am getting it right but there are times when I'm lurching especially in 1st and usually around a corner (at a traffic light turning right for instance).

    This morning on the way to work I had a minor scare when for an unknown reason (to me) the bike lurched a fair bit in traffic and I came close to hitting another biker who happened to be in front of me. I'm not exactly sure why it happened but I'm sure it was caused by me somehow.

    As I'm a new rider I don't expect to be perfect but I'm finding it difficult to learn smoothness on the throttle, it just seems like sometimes it is an on/off switch at low speed which does not inspire confidence!



    I'm sure it is just a case of practice but is there any advise anyone can give me on techniques? Or is it just a case of practising slow speed manoeuvres a whole bunch? Riding the clutch more?

    Thanks in advance!
     
     Top
  2. G'day mate. CB400 typically has a pretty smooth throttle, so a bit of practice should sort you out unless your bke has a specific issue that is causing the jerkiness. But I'd suggest some car park practise - just pulling off and puttering around in first and second, doing tight curves around "cones", u turns, and learning to feather the clutch at low speeds (so pulling in the clutch a little to buff out low speed jerking). Along with this you need to get the balance of feathering and throttle control right - feather clutch, add some throttle and ease clutch out - off you go. Once you have this skill mastered you should be able to control any issues on the road with no problem. Probably some info on YouTube re feathering/throttle control as well so have a look there.
     
     Top
    • Like Like x 2
    • Agree Agree x 1
  3. Practice, practice, and practice are probably the first three things to consider, but I'm sure you already knew that. ;) Slipping the clutch and dragging the rear brake may help with the low-speed issues, but arguably not advisable to do this when you pick up a closed throttle in the twisties. The amount of throttle opening required is usually extremely small -- getting back on the power is really just a crack of the throttle.

    Like chillibuttonchillibutton said, the CB400 is certainly smoother than many LAMS bikes (Ninja 300!), however it is worth checking your chain tension, as that may be a contributing cause.
     
     Top
    • Like Like x 2
    • Agree Agree x 1
  4. Thanks for the feedback guys!
    At first my chain did have almost double the slack it should have (was almost 60mm!) I fixed it and now the slack is within range but I really didn't notice a difference to be honest. The chain tensioners are however just before the "replace chain" mark, the previous owner claimed to have changed the chain recently before I bought it but that could have been BS.
     
     Top
  5. what chillibuttonchillibutton and DrSleepyDrSleepy said - continue to drill the basics so you can take the fright out of it. opening the throttle to turn an immediate corner can be a bit spooky for new riders. don't be afraid to let the clutch out slowly and give yourself enough revs. you won't lose control because of higher revs if your clutch operation is slow and deliberate - this is why many learners stall over and over again as they are concerned about a mono or lurching ahead at a rapid rate.

    best of luck blue!
     
     Top
    • Like Like x 1
  6. I don't spend much time in 1st on my CB400, it's a really short gear. I crawl around stop start traffic in second and feather the clutch. Even when you launch from the traffic lights I'm pretty quick to change, the magic happens in second :cool:
     
     Top
    • Agree Agree x 2
  7. +1 on keep the revs up a little and use clutch control. A little back brake can act to absorb some drive line jerkiness if that is the issue.

    When you ride, do you lean on the bars ? If you do, then you may find that every time you hit a little bump or imperfection that you jerk the throttle. If your suspension is on the hard side this may make it worse. If you support your upper body with your core muscles and grip the bike with your legs, there should be virtually no weight on your hands and your elbows will be bent a bit so that they can absorb some of the movement and you don't jerk the throttle around so much. Maybe have a chat with some mates or find a local mechanic to help you make sure that your basic suspension set up is right. Keeping your weight off the bars also allows you better control of your steering inputs and if you're gripping the bike with your knees, you won't slide forward into the tank as hard if you do an e-stop.

    60mm of slack could not only cause some snatchiness, but it could cause rapid wear on the sprockets as well as the chain itself. New chains may have a bit more stretch initially, but not that much. If you're at or close to the limit marker, then I doubt that it was a new chain although leaving 60mm of slack in it would accelerate wear. When you adjusted the chain tension, did you check the chain for tight spots and make sure that you give it the recommended slack at the tightest part of the chain ? Have you checked the sprockets to see if there is excessive wear, damage, missing teeth ? If you grab the chain, or slip a key behind a link at the back of the rear sprocket, can you pull the chain away from the sprocket ? If so, how far ?
     
     Top
  8. Weight off the bars is a good point, that might be part of my problem. Now that I look back at the incident (I had a gopro running) it looks like I had just hit a small bump in the road, extra weight on the bars might explain that although I try to keep my elbows bent as they teach in the pre-learner course.

    As for the chain system, I checked the sprockets when I was doing the adjustment and they appear to be in good nick. I didn't check for tight spots in the chain though. I'm not sure what you mean by "tightest part" of the chain? I checked the slack on the lower portion of the chain mid way between the sprockets as indicated in the user manual. I will probably give it a good check over again this weekend if it's not raining.
     
     Top
  9. too tight on the bars is a big issue - recommend all riders read A Twist Of The Wrist II by Keith Code.
     
     Top
  10. As others have said, at slow speeds slip the clutch a little to make it smoother. It becomes automatic as you get better, and the jerkiness will disappear.
     
     Top
  11. That's good news that the sprockets look OK.

    So you're checking the slack in the right position, as per the manual, but as chains wear, some of the links can get tight and don't move as freely around the linking pins. So the chain has less flexibility at that point. The effect of this is that the chain slack may not be consistent at all points on the chain. You need to allow enough slack that you are in tolerance at those tighter points. If you run the bike forwards a bit, check the slack move it a bit more, check again. You should have covered the whole length of the chain. This is usually mentioned in the manual.
     
     Top
  12. Thanks a lot for the info, I did read that section to check the whole chain length in the manual but I have a really restricted area to work on the bike so I didn't do it, perhaps I should invest in a rear stand.

    As for the jerky throttle, as I rode home today (luckily missing all of the rain) I observed a few things. Firstly the jerkyness I'm describing mostly seems to happen when I've cracked the throttle off and then back on again (e.g. in very slow moving traffic when it can be hard to keep a constant speed), secondly I was tending to "death grip" the handlebars especially in traffic which most likely was making this problem worse.

    Thanks for everyone's replies, you've helped another beginner in their first steps!
     
     Top
  13. that is why so many riders have a blown out right forearm and tired grip. get the book mate, it's on ebay, it will help.
     
     Top
  14. Thanks! Book ordered.
     
     Top
  15. -Get the bike out of first and into second as soon as you can (first is only used for getting moving, uturns or very slow riding).
    -If you need to go slow lightly drag the back brake and slip the clutch as opposed to opening and closing the throttle.
    -Don't fight the bike, the bike will want to wobble and require more control input.

    Chain will amplify the lurchyness in a way however it won't generally cause it.
     
     Top
    • Agree Agree x 1
  16. Is yours a EFI CB400? Pretty much all EFI bikes have a little lurch coming off no throttle due to the way EFI dumps fuel in suddenly the EFI sees the engine going from lean burn idle to acceleration and just dumps fuel in as it does in a car, in a car you don't notice it due to the power to weight ratio being so different, and the amount of slop in such a long drive train compared to a motorcycle. Bike makers could probably avoid this but it's significant development time and depending on the solution may impact performance. You can avoid it with some clutch control, as posts above have mentioned, just ride around a car park using throttle and clutch til you get it smooth, if you can't using those two inputs, add rear brake. Unlike a car your throttle, clutch and brake are not only speed controls, they're also stability controls. On my EFI bike in heavy traffic, especially filtering I tend to always be on the clutch, just before the bite point using it as a secondary power tap, tending to keep the throttle constant and modulate the clutch.
     
     Top
  17. Sounds like you've got it worked out. Nothing like practice.
     
     Top
  18. That's interesting about the EFI, mine is an EFI model so I guess it will have the same problem. More clutch seems to be the way to go along with the other suggestions.
     
     Top
  19. It is annoying. I'm thinking of getting a throttle tamer.
     
     Top
  20. The CeeBee is low geared and therefor twitchy in first, so ANY small input to the throttle in 1st will see you jumping around.

    As previously stated, get it into second once you moving, it will be much smoother. (Unless your making tight turns, then you gotta be smooth)
     
     Top