Hi guys , 07 xx with yoshi muff on her , k&n air filter . Looks like it’s got a tuner of some type under seat . Not sure when plugs changed they are a nice colour on electrode . Bike starts and runs nice but then sounds like it gets Rich and stumbles at idle , it rides fine but when throttled back starts popping back through muffler . Thinking of puttin new plugs and genuine filter in . What do you guys think ? . Any help appreciated 😊😊. Nick
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Yes, an 07 FI model. Should be in newer shape than my 05 with 130k kms, so probably not having age related issues yet....... I suspect the tuner is the problem. I have a 20yo K&N filter that followed me from my 02BB, so it has done 54k+130k kms and is still ok....but I have never changed the pipes.
A fuel injector cleaner treatment over 1, 2 or even 3 tanks might cure the issue as silt builds up on the intake valves (you can see it if looking down the intake manifolds).
The iridium plugs really do last 45k kms and ULP is very hard to read anyway. One issue with K&N type filters can be over oiling. This will cause rich running if the O2 sensor has been disabled.
It's bound to be a simple fix, but new plugs and a paper filter is money well spent. Do not pay for valve clearance checks until 100,000kms (ask me how I know) and all the chat about cam chain tensioners is history on late model BB's ( mine lasted to 114,000kms).
A possibility could be the FPR leaking, but it should cause bad idling and loss of power and the oil dipstick should smell of fuel. An easy check is to dislodge the vacuum hose from the FPR and see if it is wet. Unlikely, but it is 16yo.......
Late thought...sounds like it has a 4-1 system? This could be an issue if not tuned in properly or if the O2 sensor is failing (if still there). That's probably why there is a piggy back tuner under the seat......so if all the simple stuff is good (battery, filter, plugs, FPR, hoses, throttle body synchro) then it might be the tuner that has quit.
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