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Offline ivor hugh jarse

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clunk into 1st gear
« on: 19 July, 2020, 12:51:57 PM »
I've just done chain and sprockets and acquired a clunk into first gear. I removed the clutch slave cylinder and push rod and all seems ok so I did a clutch fluid change but nothings any better. its sometimes a heavy clunk sometimes light - I'm considering riding it a while and see how it progresses.. the clutch is biting early but it is definitely out of gear when the clutch is pulled in in

any ideas?   
Always carry a flagon of whiskey in case of snake bite..... and furthermore always carry a small snake.   W.C.FIELDS

Offline Admin

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Re: clunk into 1st gear
« Reply #1 on: 19 July, 2020, 01:07:53 PM »
Pretty normal on this engine IMO, same with the FireBlade.

Offline Art

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Re: clunk into 1st gear
« Reply #2 on: 19 July, 2020, 01:18:34 PM »
Its what they do. I put it mostly down to chain adjustment, when I get my chain slack just right there's a light clink. At other times there's a fairly hefty clonk that can sometimes become heavy enough for the whole motorcycle to give a little jump. If the chain is adjusted correctly that's about all you can do unless you want to strip the clutch plates out for inspection.

I'd It could be an engine oil issue or a sign of worn clutch plates. Others will be along soon explaining a method of holding the clutch lever in for 5 seconds or so before engaging gear to reduce the clonk to a clink but all you're doing there is allowing the oil more time to do what it does between the clutch plates.

Offline ivor hugh jarse

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Re: clunk into 1st gear
« Reply #3 on: 19 July, 2020, 01:57:42 PM »
It wasn't a problem until i removed the clutch slave cylinder to do the chain so i may service the slave cylinder as thats the only thing i touched
Always carry a flagon of whiskey in case of snake bite..... and furthermore always carry a small snake.   W.C.FIELDS

Offline Art

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Re: clunk into 1st gear
« Reply #4 on: 19 July, 2020, 02:12:55 PM »
Of course everything you've touched would also include the chain, sprockets, chain tension, rear wheel alignment and what ever I've missed off the top of my head. Did you clean up the gum line on the clutch push rod and lubricate the end with a dab of silicone grease?

Offline ivor hugh jarse

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Re: clunk into 1st gear
« Reply #5 on: 19 July, 2020, 06:48:19 PM »
I did yes but I cannot see how anything after the drive sprocket makes any difference to the clutch / gear engagement.  Surprisingly the ride sorted it within a mile and its fine now. Yet while in my workshop and garden it had a vicious clunk that I will find the answer for   :006:
Always carry a flagon of whiskey in case of snake bite..... and furthermore always carry a small snake.   W.C.FIELDS

Offline Art

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Re: clunk into 1st gear
« Reply #6 on: 20 July, 2020, 10:19:27 AM »
Its all in the gearbox with a little help from the clutch at one end and the rear wheel at the other.

The gearbox input shaft is always spinning because the clutch plates slip and the clutch basket and hub never completely disengage. In neutral the output shaft is prevented from spinning by the drive chain and rear wheel. The clunk is caused when first gear is selected because the input shaft is forced to stop. If the drive chain is too slack the clunk is louder because the output shaft is allowed too much movement as it meshes with the input shaft. This can be seen by the bouncing of the rear chain as first gear is selected. Big clunk big bounce too much slack, little clunk little bounce just right.

Offline KiwiBob

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Re: clunk into 1st gear
« Reply #7 on: 20 July, 2020, 11:14:09 AM »
I think Art is on the money here. If it bothers you I pull in the clutch, roll the bike back maybe 10-15 centimetres while I'm sitting on it and then engage first gear. It usually takes the slack out of the chain and first gear engages sans clunk.


Offline ivor hugh jarse

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Re: clunk into 1st gear
« Reply #8 on: 20 July, 2020, 08:06:04 PM »
I think that is the case - I fitted chain and sprockets then had by wife sit on the bike to set the chain. I then placed it on the main stand to torque the axle so everything was suspended when I fired it up and clicked it into gear,

Riding it with my weight on it turned must have put everything back to normal   
« Last Edit: 20 July, 2020, 08:07:41 PM by ivor hugh jarse »
Always carry a flagon of whiskey in case of snake bite..... and furthermore always carry a small snake.   W.C.FIELDS

Offline raYzerman

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Re: clunk into 1st gear
« Reply #9 on: 20 September, 2020, 03:58:17 AM »
First thing I do in these situations (any bike with hydraulic clutch) is flush and bleed it, then remove the clutch lever and check the brass bushing that engages with the master cylinder.  If it's been a while, chances are it is worn oval/scored and you are not getting full master cylinder travel.  Cheap to replace and grease it with silicone grease that won't wash out.... check it annually.  It's amazing how a little piece of brass can cause problems.
« Last Edit: 20 September, 2020, 03:59:00 AM by raYzerman »

 


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