RiderSite.com - Motorcycle Forums

.
Recently I ran my bike for a 100 miles or so without an air filter whilst waiting for my K&N replacement to come.

Now that I've fitted the K&N filter the engine speed fluctuates at idle speed intermittently and consequently I have set it to idle at around 1700rpm to make sure it stays running (was very nervous when got stuck in traffic behind an unmarked car since rather meaty exhaust tone!)

Now...as well as fitting the K&N I topped up the Scottloier reservoir which had been empty since I got the bike - it of course has a vaccum line running back to the vacuum line that comes out of some sort of component fitted to the underside of the airbox. I have now noticed that if I so much as nudge the vacuum lines under the airbox by even a millimetre the enginee speed changes dramatically which seems strange.

Any ideas what might be happening? I'm at a loss.

Cheers

Martin

Sounds like you have a leak. Those lines are very fine and they do deteriorate. You have disturbed them fitting your air filter so I would check the lines and that they are fitted OK

That "componant" is the vacuum sensor for the FI BTW

Could be vacuum sensor failure? Think I've read of one going tits up on one of the Aprilia forums recently.

I run my oilier from one of the brass spigots (normally capped) that pokes out of the side of the throttle bodies. Seems to function perfectly well there.

You have got the filter seated and sealing correctly haven't you? Same with the airbox lid? Strip it down and run some silicon grease round all the sealing edges before reassembling it again and check the thin gasget round the airbox lid is intact to be sure.

..
Filter is seated well as is air box cover. Might have a look at the vacuum sensor tho.

Cheers

It does sound like a vac pipe has come off. If that's the case, it'll fart n' pop on the over-run too.

.
Thanks guys you were (as usual) correct - one of the vac pipes had split where it slip sover one of the connectors. Hardly visible but enough to cause problems.

Now she's running as sweet as I could wish for.