Hi,
I have GK73a which sounds very poorly, having just completed a race and decelerated from approx 13000 rpm I noticed a sever knocking and bluuurb when I opened the throttle. The bike started easily from hot or cold afterwards but the noise became more apparent when you reached about 5000 rpm, suspecting the cam chain I checked it and found the timing at 20 links not 19 between the 2 marks as described in the manual. Having read all the material I can find regarding this setting I have subsequently set it to 19. However this seems to have made little difference, so I swapped the tensioner for a newer one just in case but still no difference? Any ideas would be greatfully recieved, I have uploaded a vid to You Tube if anyone would care to listen? It is difficult to hear the specific noise but it really does sound like a knock rather than a ticking. Thanks for any advice in advance.

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A new cam chain is what you need i reckon new tensioners can't fix a stretched chain as it only tensions the chain on one side so the other side is then too long and moves the timing of the cams.

20 links is what its supposed to be and get a race tensioner and ride it they move the chain further

Many Thanks,
OK so 20 links I'll reset that.
Why would the noise happen so suddenly? I have actually run it with a screw driver tensioning the tensioner, but the noise hardly changes? I was beginning to suspect the bottom end might be going but have never heard that sort of noise before so haven't got a clue really.
How much for a race tensioner? Are you the guy that does the big bore kit?
If so how much, what does the kit include and what head work is required?

You may want to check if you broke a spring or a rocker both common the auto tensioner only goes out so far but the chain is still with in spec and the manual race one goes way further in to get more life out of the chain... Cost for the Tensioner is $75.00 shipped and comes with gasket and directions to install... As for piston kit due to our president the price has rose it is a street kit which is made for the tunner i have a dyno chart of a bone stock girls bike with the kit in it stock pipes and all else stock pushing 63 hp with 31 ft/pounds of torque not a lot, i also have a friend in Canada that races one and he instantly dropped 4 seconds off his time and is running up front now but i have no dyno chart for his bike...Mine is milled and putting out around 75hp with flatslides FCR's... So depending on the mechanic doing the work is what you get. Kit comes with head and base gaskets race tensioner right and left cover gaskets 4 pistons and rings 2 grams heavier than stock and instructions $1000.00 shipped all prices are US failing economy prices... you can email me at jbird474k at hotmail.com