random knock on idle?

[lumpyv]

hi every body. anyone know whats up with my bike? it starts on the button everytime , warms up nicely, pulls like the proverbial train through the gears , dosent back fire just that lovely burble on the overrun but occasionally when im sitting at lights or whatever at tickover theres a scary sort of knock from the engine, the revs momentarly drop from idle of about 1250 to 900 then its back to normal? the lights change and im off as normal running like clock? is this a problem or is it just a "they all do that mate" type of thing? its all standard except for quill exhausts.

thanks in anticapation

[pinkyfloyd]

I'm under the assumption its normal. Mine goes the other way. Ticks over at around 1K revs happily and now and then kicks up a little.

[gordthebiker]

Mine does the same, some guy made a video of his here
Mine doesn't do it as often as his though....

[Eclectic]

Mines not that bad, but my idle is a bit erratic, yet open the throttle and she's off.

Ive had the carbs cleaned and balanced and it didnt fix it, next, as was highlited on here, is to check the idle jets arent full of sh1t.

[lumpyv]

oh well its reassuring to hear other people have similar experiences! i dont mind the revs dropping its the clonk i dont like!.

spoke to guy this morning whos got some 1600cc v twin cruiser or other and he recommends getting the carbs checked out for balance so who knows?

thanks for the input so far.

[tony.mon]

It's normal, most people call it a cough through the airbox.
It's just because of the huge carbs.
Turning tickover uo to 1300 or so helps, and as you've already found, carb balance.