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How to stop the ‘clunking’ and the drag back on Petrol motorbikes


emmajaneg
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So I have a petrol bike and I’m still trying to set off smoothly. I can do it on most occasions but there’s still the clunk and a bit of delay before you can change to second. How can I set off smoothly without either stalling or making an awful set off ! Thanks

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There is a bit of an art to shifting nicely from 1st to 2nd on a 125 as 1st is so very short. A well adjusted chain will help but at what revs are you trying to change up? 4-5K would be about right, at a guess..

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Practice ! . Some bikes are smoother than others plus older bikes that have had a hard life at the hands ( And feet ! ) of inexperienced riders will clunk more than fresh new ones . This is known as lash in the drive train . Stick the bike on its centre stand with the back wheel off the ground . Put it in first or second gear and grab the back wheel and move it back and forth . Notice how it moves quite a way in each direction before you can't move it anymore ? That's your clunk . It's caused by all the little bits of wear in the clutch and gearbox parts being added together to create an area of slack between the engine and the back wheel. It's nothing to worry about . Sometimes a new clutch makes things a little smoother and correct chain adjustment certainly helps . A new set of cush drive rubbers in the back wheel is another way to improve matters. At the end of the day you just have to be gentle with it . Close the throttle, pull in the clutch , select your gear and let the clutch back in gently as you roll on the throttle again. Practice makes perfect.

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A few simple adjustments and a couple of easily user-replaceable parts tightened my old ZZR1200 up no end when I got it, just as Bob suggests.


Then I swapped it for a Harley, and the belt drive was even smoother. Then I swapped that for the BMW, and the shaft drive is better still!

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The thing about 125s is that they have lots of rotating mass but not much power. When you pull in the clutch without releasing the throttle you get loads of revs. When you dump the clutch all the slack gets taken up quickly so it snatches, but the revs drop sharply because there is no power.

Practice slow speed clutch control, motojitsu style, in first. Then transfer that skill into the change between 1st and 2nd.The trick it to slip the clutch more than seems necessary without loosing all the revs. It's harder with a 125 than a bigger bike.

Or repeated slamming the gears really has worn all the contact, points. How old is the bike (miles)?

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