Knocking from between footpegs

kooga13 · Two Stroke Sniffer Joined: 14 Apr 2010 Karma :

Hi, my Sprint 955 ST has developed a knocking sound which seems to be coming from between my feet. Bike is a 2000 model, 40k on clock, last serviced about 300 miles ago. I can feel and hear a clunk when opening the throttle and also when closing the throttle, it feels like something is loose. When i ride slow and lightly flick the throttle open and closed the knock is really bad. Theres no noises when the engine's ticking over and it doesn't do it when the clutch is disengaged. It's got progressively worse over the past few weeks and I can now feel a bit of a knocking between the pegs during normal riding. Theres also a very small oil (i think) leak, just a few occasional spots after a long ride. I think it's coming from a very thin tube (looks like a wire) that's hanging loose just above the gear lever. Oh, and first to second is very stiff if the bike is cold (not sure if these things are related!) Any advice or obvious things to check would be much appreciated, Cheers

Paxovasa · World Chat Champion Joined: 25 Apr 2010 Karma :

Check the chain for tight spots, check the centre stand (if one fitted).
____________________
Suzuki GSF600 K3 (in the fastest colour, black).

kooga13 · Two Stroke Sniffer Joined: 14 Apr 2010 Karma :

Centre stand is ok, chain seems fine and is well lubed. Will read up on tight spots (im fairly new to all this), check and get back. Thanks

Acemastr · World Chat Champion Joined: 01 Oct 2008 Karma :

I get this on my CBR, word has it it's the final drive bearing but I've not confirmed this, if you do find out please let me know!
____________________
2017 KTM 350 XC-F - 2014 Yamaha R6 - 2005 Yamaha YZ125
2016 Toyota Tacoma Limited

jowettdriver · Borekit Bruiser Joined: 09 Sep 2008 Karma :

From what you describe it sounds like something to do with the transmission or final drive.
Are the front and rear sprockets corectly fitted? I have known the front sprocket to come loose and chew the splines causing knocking sounds to come from the transmission. (although this was on a cg, so not sure if the sprint has the sprocket attatched in the same way.)

Cheers
Tim.
____________________
Bikes: 1980 Honda CX500, 2003 Honda CB250, 1980 Honda CG125

kooga13 · Two Stroke Sniffer Joined: 14 Apr 2010 Karma :

There is some lateral play in the rear sprocket, not sure if this is normal? i'll have a look at the front sprocket later - what should i look for? (i.e. whats normal?). sorry if this is a stupid question lol

jowettdriver · Borekit Bruiser Joined: 09 Sep 2008 Karma :

Not a stupid question at all!! I probably should have explained better.

When you say there is some lateral play in the rear sprocket, how much do you mean? Roughly how far does the outer edge of the sprocket move when you pull at it?

As far as the front sprocket is concerned, if the sprocket is the splined type then it should be a nice snug fit over the splines and held by the locking ring with no visible run out (no sideways movement or wobble)

Cheers

Tim.
____________________
Bikes: 1980 Honda CX500, 2003 Honda CB250, 1980 Honda CG125

kooga13 · Two Stroke Sniffer Joined: 14 Apr 2010 Karma :

hi ,theres probably about 3 - 5mm lateral play in the rear sprocket. what are splines?? cheers!

Paxovasa · World Chat Champion Joined: 25 Apr 2010 Karma :

ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

[quote="Paxovasa"]

Paxovasa · World Chat Champion Joined: 25 Apr 2010 Karma :

jowettdriver · Borekit Bruiser Joined: 09 Sep 2008 Karma :

kooga13 · Two Stroke Sniffer Joined: 14 Apr 2010 Karma :

Tightened up rear sprocket bolts and there's no play now but the knocking is still there. Did some investigating last night: took the front sprocket cover off & it looked fine but i took some pics so i'll post them later. chain had about 30mm of play at the centre of the lower part - is this excessive? also noticed that when the bike is in gear and being rolled back / fwd with clutch in, it clunks when first pushed. it doesnt do it in neutral - again, not sure whether this is normal?

ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

Paxovasa · World Chat Champion Joined: 25 Apr 2010 Karma :

ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

jowettdriver · Borekit Bruiser Joined: 09 Sep 2008 Karma :

If you can find no problems with the final drive, (chain and sprockets) then i'm afraid that the problem is likely to be within the transmission. Its always worth checking the simple things first though.
The stiffness in the change from first to second when cold, has it always been like that or has this come on over the last few weeks/months?

It sounds like you have some play somewhere within the transmission, it is at its worst when moving from power to the overrun, but has now started to knock all the time, suggesting it is getting worse. If the stiffness in the change is a new problem then this also points in this direction.

I'm sorry I can't be of more help, but unless you live near Norwich I think it is time to get someone to look at it for you.

Cheers

Tim.
____________________
Bikes: 1980 Honda CX500, 2003 Honda CB250, 1980 Honda CG125

kooga13 · Two Stroke Sniffer Joined: 14 Apr 2010 Karma :

thanks for all the advice, i'll take it to a mechanic Crying or Very sad

and post an update when sorted