My bike developed a fault a few days ago in that the engine is lumpy and down on power from tickover up to about 3000 revs. Above 3000 revs it's sweet as a nut and pulls like a train. I fitted a new air filter and plugs (it was ready) in the hope that that might cure the problem but it didn't. The color of the plugs that came out was fine, so no clues there. The problem occurred only occasionally initially gradually getting more obvious and persistant over a few days (short journeys). It's doing it all the time now.

Any pointers to what I should be checking would be most welcome.

I'm not that experienced with troubleshooting fuel injected ECU controlled engines but I'm no dunce with the spanners and a multimeter, but generally on older carburetter machines.

TIA

 

Is it fitted with a PC or similar?

 

Everything is bog standard.

 

Compression Test, Fuel Pressure Regulator Test, any codes

 

How many miles?

 

24,000 miles on the clock - and none of them particularly harsh.

Thanks for the 'codes' tip CaBaRet - I'd completely forgotten about that feature. I checked and there were four - but as I've been unplugging stuff over the last few days while investigating the problem I can't be sure some of those aren't self-inflicted so I've reset the fault code memory this evening and we'll see what's there after a blag round tomorrow.

There is an added complication that's developed though. A few days ago the problem went away briefly then came back the following day (and "no", I hadn't fiddled with anything in the in between that may have instigated this). And when I took the bike out for a spin this morning it seems to have gone away again. Don't you just love an intermittent fault?

 

There's no evidence that the FPR is passing fuel to the vacuum pipe. I don't have a pressure tester to test the pressure in the fuel rail so that test will have to go on the back burner.
And my cylinder compression tester doesn't have an adapter to fit the sparkplug holes on this bike so that will have to wait too.

 

No progress today. It's Bank Holiday weekend and the sun's out so I should be out on the bike . . . but it's still poorly . . . so I've been to the pub.

 

Finally got round to having another play with the bike last night (after being kept too busy childminding grandkids for most of the Easter hols) and found these lines on the ceramic of no. 1 (brand new) sparkplug. Is this evidence of 'tracking', and if so, what's to be done about it?

 

Hi matey , where did you buy the plugs from as there is a large supply of fake plugs around,check this out against your plug just in case
https://www.slideshare.net/athangal/...ngk-spark-plug