that 1st gear clunk

[Groggles]

so i've read the posts and must admit by trying almost converted to the clutchless upshifts. can't quite get down right. the question tho is how to get rid of the first gear 'clunk'. sitting at the lights looking cool and select first and 'clunk'. tried pumping the clutch, low revs,higher revs, blip the throttle? i am assured clutch adjustment is right. whats the trick???
any advice???

greg

[icebreaker]

possibly abit of chain adjustment, and high revs... As far as I know your going to get some movement/clunk. get these right and you'll prob get it as good as it will get..

I found a lose chain means that there is more movement in the front sprocket which teans to give abit more of clunk/surge forward.


Dan

[Nanna10r]

We've covered this one before Mate, Wasn't a bad thread if i remeber right either.

Adjust till the cows come home it probably wont remove it. Traditionally Kwika has made some of the most powerful engines in bikes & have a reputation for Strong gearboxes to cope with the higher outputs.
Spin off has always been Noisy boxes, enjoy it ..... I do.

Cheers Brett

[Neka79]

buy a car...ive had abt 6 bikes, and ridden abt 10 others, and theyve all
dun it..get use to it..
Neka
2000 CBR 929RR
1988 KDX200 thrasher
1996 VS SERIES 2 UTE
"dont hate me cos im sexy, hate me cos ur mrs thinks im sexy"
----- Original Message -----
From: "recycled" <gregsu@bigpond.net.au>
To: <ksrc_gendisc@ksrc-au.com>
Sent: Tuesday, October 26, 2004 9:06 PM
Subject: that 1st gear clunk


> so i've read the posts and must admit by trying almost converted to the
clutchless upshifts. can't quite get down right. the question tho is how to
get rid of the first gear 'clunk'. sitting at the lights looking cool and
select first and 'clunk'. tried pumping the clutch, low revs,higher revs,
blip the throttle? i am assured clutch adjustment is right. whats the
trick???
> any advice???
>
> greg
>
> ----------------
> Sent using Mail 2 Forum (http://m2f.sourceforge.net)



Post generated using Mail 2 Forum (http://m2f.sourceforge.net)

[Wannabe]

It's not really a problem, but if you are interested in trying to reduce the occurence of the dreaded CLUNK here are some suggestions.

Try pulling the clutch in & holding it for a few seconds longer than normal, before engaging 1st gear. I do this whenever possible and it will usually reduce the noise or prevents it happeneing at all.

Also, different oils & a different oil level can have an effect. For example, next time you change your oil, try topping-up to just half-way between the top & bottom lines on the sight-glass instead of all the way to the top.
I've found that Shell SX4 (semi-synth) is good for improving gearbox/clutch smoothness & operation and helps reduce the noise in conjunction with the "hold the clutch in & wait a few extra seconds" technique.

[Nanna10r]

Wanna would that give less oil pressure ?, not filling it to the top line ?. Pretty interesting point you have made there champ. I would be like to learn how this would lessen the clunk & what long term effects it would have on the motor.
Cheers Brett

[Wannabe]

Oil level has nothing to do with oil pressure. As long as the oil level is up to the bottom line as a minimum or higher, then your engine has all the protection it needs. I'm a qualified auto-technician with 13 years experience (but I'm no longer a practising grease monkey ) and I wouldn't suggest anything that would not be good for your motorbike.

Let's think about why the CLUNK occurs in the first place.
You pull the clutch in, the clutch disengages the crankshaft from the gearbox input shaft. BUT the oil that our clutches sit in creates drag between the clutch plates. This drag in effect acts like the clutch not quite being in all the way and so the gearbox input shaft is actually still spinning. When you select 1st gear, the input shaft (which is rotating) engages with the ouput-shaft, thus connecting the engine (via the clutch's frictional rotation) to the driveline. The drag in the clutch plates obviously won't be sufficient to actually move the bike forward (well not far anyway) but it is enough to suddenly take up all the drive-line slack inside the gearbox and in the final drive (chain/sprockets etc). The result is the CLUNK that we all know and love.

Now I'm guessing that by holding the clutch in for a few extra seconds, it allows the shaft to stop spinning (or at least slow down) as the friction of the gearbox shaft rotation overcomes the friction of the drag of the oil around/between the clutch plates. A lower oil level would cause (slighlty) less frictional drag on the clutch plates which perhaps assists in allowing the input shaft to actually stop turning (or slow down) before engaging 1st gear.
I'm no engineer but I think my concept is reasonably correct.

But let's not forget that this noise doesn't really hurt anything or indicate a problem. It is inherent in the design of our motorcycles.
My suggestions are just to assist those who wish to reduce the occurrence of this noise. Nothing I've suggested will have any adverse effects on our motorbikes.

Cheers - Tony

[Nanna10r]

Good point Wanna, I just learnt something so thanks for that.
Keep it coming mate, so what do you know about Air Pods considering fitting them to my little 6.
Cheers Brett

[Wannabe]

I was just re-reading my post hoping that it made sense. Judging by your response it did. Right or wrong at least I made sense

Now by Air Pods, do you mean individual air filters for each carb?
And what is your little 6 exactly?

[MickLC]

I've got a couple of steep hills that I roll down in slow moving traffic on the way to and from work. I usually pop it into neutral and roll down them 'cause I can't be bothered holding the clutch in for 5 minutes straight. What I do find though is that when I am rolling slowly then pull the clutch in and pop it into first it is as smooth as silk, no clunk at all.

[Smitty]

Tony
correct in what you say
but I might add...
the problem is compounded by motorcycle gearbox design.
Bike gearboxes do not use a synchromesh mechanism (like a car)
to engage gears. A synchro mechanism brings the speed of the gears
being meshed together to the same, so the gears mesh 'silently' (no clunk)
That is not the case with a bike, so every effort to reduce the speed of the input shaft on a bike (like holding the clutch in longer) will reduce the clunk when it engages with a stationary gear in the transmission

hth

cheers

[Wannabe]

the problem is compounded by motorcycle gearbox design.
Bike gearboxes do not use a synchromesh mechanism (like a car)
to engage gears. A synchro mechanism brings the speed of the gears
being meshed together to the same, so the gears mesh 'silently' (no clunk)
That is not the case with a bike, so every effort to reduce the speed of the input shaft on a bike (like holding the clutch in longer) will reduce the clunk when it engages with a stationary gear in the transmission

Your reputation precedes you & appears well earnt oh great one YODA.
I'm aware of the differences between bike/car gearboxes but in an attempt to KIS I left it at

... It is inherent in the design of our motorcycles.

& I wasn't going to go there.

But you have put it more simply than I could have managed and have now neatly completed the pieces of this puzzle.
A good mornings work all round. Time for lunch I'd say

[icebreaker]

hahahahaha.. Looks like a Tag Team Effort..

[Nanna10r]

Wot Free Lunch again ???? . Os so fellas i was doing ok with Wanna's explanation, then i read the Big Master "Y's & didnt see how they correlated at all ?, I thought it explained differences between cars/scoots & failed to see exactly how it reinforced the earlier posts.
Also Ian whats this hth you toss in every now & then. Not some secret Masonic Handshake Conspiracy Theorists Implement or notification is it ?.
Cheers Brett.
Be back for supper again later, thanks.

[ty]

hth = hope this helps