I have an odd sound coming from the bike when I am on the move. It started about the same time I fitted FCR's (as much as I can remember). It is like a cross between whistling and bearing howling sound. However unlike failing bearing sound it is always constant tone when it happens no matter what speed (or what engine speed). Only thing that happens to the sound is it is being interrupted with the vibration of the engine (not chain slack). What I mean is imagine trying to accelerate on a V2 from to low gear at speed (where there will not be much or any chain slack) it will interrupt with each vibration and as vibrations come closer together so does the interruption of the sound. It happens from about 10 mph up but wind direction, speed and bike lean angle can change that which leads me to think it is the FCR butterflies. Engine hot or cold makes no difference as well. So far I have tested the rear wheel bearings and it is smooth as a kitten, same front. Chain is not to tight but it also happened when chain was on slack side. I have fitted another pressure plate from SS and sound still there. I have also put bike on paddock stand, in 1st and spin the rear wheel no sound. Did not test under rear brake load yet. The sound is gone under engine braking Only thing I did not test yet and could are belt tensioner bearings but saying that sound would oscillate and change with engine speed right? Finally when doing 30mpg down hill I have killed the engine and sound was kind off there but less noticeable. Honestly any ideas?
Pop the old carbs back on Lucasz and see if its still there ....did you get the bearings by the way ?
Not certain what you mean by bellmouths, I have airbox on them so there is a alloy adaptor so that I could link fcr's and airbox.
If your FCR's have throttle butterflies then they're not FCR's .... they have flatslides, and it's these which raise the needle/expose the aperture .... If the noise is a 'clacking' sound, then it's just the slides rattling under pressure changes that you can hear .... nowt to worry about.
Ok yes slides not butterflies. Clacking sound I can hear and I like it but it is not that. Try whistling gently that is the closes to the sound I can hear. However rather then it being smooth uninterrupted it is interrupted with bike vibration until vibrations are so frequent that sound appears to be constant. To add today I went via overpass that had 1m high walls on each side. I moved my head around from left to right to hear the sound that was bouncing back and the noise is constantly the same weather I listen to it more from the right or left.
Does it by any chance become a sort of shrieking noise, almost like a slipping fanbelt or empty tank vibrating on the frame? AL.
Mine would do it at around 2200-2500 rpm when it had got warmed up........usually when blipping the throttle and the revs dropped back.....sometimes at approx 30mph and I could hear it above the general engine / exhaust noise. I always thought it came from the right hand side, somewhere between the vertical cylinder head and the crankcase, but despite checking belt roller bearings etc etc I could never find it.....I even played around with the rubber (or whatever) inserts between the head and barrel fins which are supposed to stop a ringing noise..... ....However, since having had the carbs on and off several times (and found ill fitting seals particularly those at carb to airbox) and having fitted a half fairing, it doesn't seem to be there anymore (or I don't notice it).......mind you, it's a noisy engine anyway.....at least I think it is, compared to other bikes I have owned. AL.
If I blip the throttle standing still I get nothing. Bike has to be moving and under load for it to be most noticeable. Under engine braking it is slightly there but sometimes. If I get to for example 50mph and am in 5th then settle for that speed it will go away until I put more load on engine by accelerating. I was thinking it is output shaft but then it would make a noise at 30mph down hill in neutral with engine off but no. Only thing I can think off is wheel bearings so will replace rear again and see if it goes away. If not no idea. It is not the front as I can hear the noise coming from under a tank defo not front.
