I just got back from Key West a 2100 mile round trip . I was on a 07 SEUC and had the other guy on an 08 SEUC . They both sound like type writters going down the road . They ran great but the engines are very noisey . The 07 has been in the shop twice for rear cylinder rebuild with only 8k miles on it . During the trip the rear base gasket started seeping . He got a hold of the harley rep and told them he wanted a new motor . He didn't want to have a bike with 9k on it rebuilt 3 times . They are supposed to call him today . I have a 150 +hp 124 that makes much less noise than the 110 and it has 13 to 1 compression .
They may say it is normal but it is just a cover up . There is nothing normal about a top end that makes that much noise . My 113 doesn't make any where near that much noise if it gets hot in traffic .
If the rocker arms are not hitting the rocker boxes on either of these bikes (07 or 08), then the next thing is to get the Syn3 "synthetic" oil out of the bike and put Mobil 1 or Amsoil in...this will provide better lubrication to the top end of the motor and quieten things down a bit. Some 110's have clearance issues on the rocker boxes.
There are clearence issues in that motor and not just the rocker box . To make it worse HD has them running lean as hell . I have never ridden a bike that was that hot !
There has been posts about pourous metal,ask any porter what the 07 and up heads are like when reworking.Maybe its a material problem ? maybe this type of material disipates heat more readily?,echoes sound easier?thus the 07/08 gripes.