I bought a 09 street bob in may this year. the bike was brand new it now has 4000 miles. Every time i go to wash it i noticed that the top bend on my exhaust was really dirty, but i couldnt figure out why. well i went for a 800 mile trip this weekend and I tracked down the problem. it has what i feel a little bit exsessive blow by, here are some pictures, take into consideration this was 767 miles from thursday at noon to sunday at 5pm, i am running harley 20/50 for now at 5000 miles i am changing to redline or amsoil. also these were pretty hard miles, bike was around 3000 rpms for most of it....with a bunch of racing, i weigh 336 as of this moring(down from 357 and slowly dropping 2-5 lbs a week) bike was not loaded we had a chase, it is bone stock except for vance and hines short shots, vance and hines v02 intake and vance and hines fuel pac. does this sound normal? if so what is a fix so it isnt blowing all over my motor and pipes? thanks jshull

 

You may want to check the backing plate for any cracks.

 

Who is doing your service work?

Check your oil level. Too much oil is a common cause of this.

 

too much oil or aggressive throttle action will cause that.

 

i did my own 1000 mile service and plan to do them all, i dont think i over filled the motor but thats definatly a possiblity, and as far as the aggressive thorttle thats me, is there a fix? besides easy throttle?

 

Did you use three full quarts of oil?

 

more like 2.75 i think, its been a few months back i cannot really remember.

 

The manual calls for 2.5 but I put in just under that. I put in the 2.5 the first oil change and had to much blow by so started going just a little under that from then on. I get very little if any, any more and the oil level is still well in the safe range.

 

same here,2 1/4 quarts puts it a little more than halfway hot,no oil in the breather.

 

well thats what i will try next.