knocking noise!!

mirax · Scooby Slapper Joined: 13 Jan 2005 Karma :

hi wondering if any one can help im getting a knocking noise on my dt125 while im throttling in 6th gear. the noise only happens when i use the throttle in sixth no other time plus the noise goes when i let go of the trottle or pull the clutch in helppp!!

mr.z · World Chat Champion Joined: 04 Feb 2004 Karma :

Can't say from experiance bacause ive nver ridden one but it sounds just like its the noise of an engine under stress, i.e. same noise you would get trying to pull away from 10mph in 3rd gear...

If its not allways done this then it might be worth worrying about, i could be allot of things from incorrect engine timeing to knackered engine internals.. you could try a quater of a tank of optimax and see if that helps, might be wrong i'd have thought that this sort of ignition timeing knock would be all through the range...

How long have you had the bike e.c.t. have you got any history of anything thats been done recently?
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Robby · Dirty Old Man Joined: 16 May 2002 Karma :

Knocking on an open throttle in top gear- IE when the engine is under the most load.

I'd say that points at pinking, likely due to carbon build up. Run some redex through it for a few tanks of petrol, and use a decent semi or fully synthetic 2 stroke oil. Give it a good thrashing too, its a 2 stroke and its happiest being abused.

Make sure you warm it up before trying to kill it though.

You could decoke it by taking the head off and decoking normally, but redex should do the job without you having to lift a spanner.

Scotsman37 · World Chat Champion Joined: 17 Aug 2004 Karma :

In regards Redex I've just been advised by a bike mechanic never never to use it because it's crap for bike carbs as it was only designed for cars.

Best thing to do is remove the carbs and clean with it with carb cleaner and install an inline fuel filter between the carb and fuel tank to stop rust or that reaching the carbs itself.

simon1221 · World Chat Champion Joined: 28 Jul 2004 Karma :

Seems to do the job for me on my bike.
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Robby · Dirty Old Man Joined: 16 May 2002 Karma :

This needs it for the combustion chamber cleaning effect, not the carb cleaning effect.

For cleaning carbs I'd always do it properly, or use a dedicated carb cleaner. Redex cleans the combustion chamber, I'm a little dubious of its carb cleaning claims.

mirax · Scooby Slapper Joined: 13 Jan 2005 Karma :

how much redex should i use ? with cleaning the carb, it there anyway i can i do it without removing it

mirax · Scooby Slapper Joined: 13 Jan 2005 Karma :

regarding to zeros question ive had the bike 9 months has done 3000 miles. the knocking only started the other day. thing is my bike does smoke (white smoke)alot when i pull off after ive warmed it up then clears after a few meters does seem a bit choked up !!!

BFG · Brolly Dolly Joined: 14 Feb 2005 Karma :

gsxrpeak · Trackday Trickster Joined: 06 Apr 2005 Karma :

is the sound deff coming from the engine? could be something knocking when you get to a certain speed, thats why it only happened in 6th gear?
just a thought. you guys covered everythign else! Thumbs Up

mirax · Scooby Slapper Joined: 13 Jan 2005 Karma :

i found out today that it only does it in 6th until the power value opens then it stops but doesnt do it any other time !!

BFG · Brolly Dolly Joined: 14 Feb 2005 Karma :

mirax · Scooby Slapper Joined: 13 Jan 2005 Karma :

fair comment i could just be worring about nothing but best to be safe than sorry Thumbs Up

just cant wait to get my 4 stroke 400-600 fed up with these 125 two pokes

mirax · Scooby Slapper Joined: 13 Jan 2005 Karma :

the noise is a slow knock knock not very loud knocking but noiceable sound and only happens in sixth before power value opens