bit of a low idle and bogging?
 

hey all, i have a 03 cbr600f4i with about 34k miles. first off i love the bike and it runs like a champ. however, when i first go to riding, i go about 1/4 mile throughout my neighborhood to a stop sign to wait to pull out and always at that stop sign, the bike struggles to maintain rpm's it drops to about 600-700 and sometimes will cut off if i dont blip the throttle or keep it revved to about 1200ish. Also as of lately, a few times when the bike is warm (over 200 while sitting in traffic) when i go to take off, it is bogging, and i could twist the throttle all the way and the rpms nor speed will adjust at all, and after about 5 seconds all of a sudden the power comes back and normally kinna throws me back a little bit. any ideas? also at high temps it struggles to keep the rpms up at idle also. but when its between 150-190 it idles perfectly.. i changed plugs less than 5k miles ago. (yes theyre the correct plugs and yes they were gapped correctly lol just to save questions and time)

I've got potentially the same issue on a 2001 f4i - bike has been perfect since I bought it in 2006. Bike has around 38k miles. My idle has been set around 1100 rpm since I had the bike. I drive maybe 2000 miles a year, mostly around town recently - short trips that only see maybe 5 minutes of full temperature riding, which is around 215 degrees.

The warmer the bike gets, the more I experience the low idle and shutdown. The bike always starts right back up. I can let the bike sit and idle for a while and it will sputter up and down periodically. When coming to a stop, especially after using the engine to slow down, the bike will putter and stop. I can rev the engine to keep it running when it starts to do this, but in some cases the minute I let go of the throttle she dies. In some cases when I start in to first I get a bit of fluttering.

The bogging mostly happens when I'm driving on flat or downhill, with the throttle set so I am just cruising - basically very low / no load. I'll notice some fluttering that cause the bike to lurch a bit.

I've tested the FPR by checking for gas leaks, no leaking. I've examined the airbox and air filter - it's a little dirty but seems fine. I haven't pulled any plugs yet. The battery is in decent shape. I am on the second tank now since the problem started. I added a few oz of "SeaFoam" to the 93 octane from Quicktrip - so far only been a few miles so we'll see if that helps.

Any feedback would be appreciated!

I'm having the same issue

So at low temp the bike is warming up, when its doing this it adds extra fuel to burn and make heat quicker. What your describing sounds like a vaccum leak. The warm up richness would mask the leak as its probably making the a/f ratio close to correct, until it warms up and the engine leans out the fuel mixture. At that point your running much too lean. I'd check all vaccum hoses and rubber boots that attach the throttle bodies first.

Cam pos sensor

There are so many people on here having the same issue but no fix . My bike is a 2002 f4i with only 4,400 miles. I bought it from a old guy . I'm a bodyman and a ase master mechanic on vehicles and I work on motorcycles on the side and diagnosing this problem has been a week project between work and home life with a toddler lol. But I remember working on a few cars that have had the same issue. When cold it will start find and idle normal. When warmed up the idle gets really low and the engine has no power or Boggs or surges and runs really rich. Plugs foul out and even the car will stall . That all points to the cam sensor.

I've checked all the vac lines,new map,new iat,new plugs,new tps,. When I changed the plugs they were black. My mpg dropped to about 26mpg Instead of about 40ishmpg . Check the valves clearance, rsync the throttle bodies and none of this made a difference. But when I changes the cam sensor it was a running perfect .

Vac lines may be okay, but it could be ANY point between the Throttle Bodies (if FI) or Caruberotors and the head. for instance, the rubber boots that the throttle bodies/carbs connect to on the head could be bad. Seen that one more than once.... need to rule out ANY point that could be a vacuum leak upstream from Carbs/Throttle Bodies before moving on to other possibilities (for instance the rubber sync caps could go bad or even be missing and as they are hard to see to verify without removing the carbs/FI, can easily be overlooked but would act as a severe vacuum leak... seen that one multiple times too). Have seen what has been described dozens of times on older bikes, especially if they ever sat for any period of time, and in each case ended up being some type of vacuum leak which once repaired resolved the problem.