I have got myself a whirring engine, and I am unsure why! History: Bike was running perfectly smooth, I fitted new Cycle works Exactfit belts, and tensioned to spec using the Gates Carbon Drive app on the Iphone, also checked with the twist method. While out for a 150 mile ride a strange noise developed. I thought it was belt related, back at home I removed the belts again and checked the belt roller bearings finding one a bit loose and giving a metallic sound while spinning. Great I thought, and replaced all 4 bearings with genuine SKF ones. When the bike was back together, with the belts tensioned a little less, the same sound remains, I continued to ride for approx another 200 miles and it did get worse. In the mean time I did try the old belts again with the same result. The sound appears to be coming from the bottom endish, it does not sound like rumbling, more of a whirring or a scraping with vibration clearly felt on the engine side casings, more on the left side. During further investigations the clutch plates were pulled and the friction plates replace due to max wear, nothing else was observed and the sound was the same with the plates removed. In addition, I have dropped the oil and checked the catch filter which was clean, no signs of white metal or allow fragments. My next plan of attack is to pull the alternator cover, water pump etc and look for any signs of damage. I am a bit stumped just now, and hope that anyone would be so kind to listen to these 3 sound files, and give me any tips. Any help is much apprciated. http://motograffics.co.uk/Whirring.m4a http://motograffics.co.uk/Whirring2.m4a http://motograffics.co.uk/Whirring3.m4a
As the engine sounded ok before you did the belt replacement, and you have the whirring sound after you replaced the belts, I'd take a guess it's belt related. Presume you rotated the tensioner pulley the correct way? Sounds to me like one of the belts is rubbing on something.
Belts all ok same even with covers off, and yes rotated the tensioners the correct way, LH, probably did 100 miles or more before noise started, thanks.
I know it's a daft thing to say but check the obvious stuff first... make sure that there's nothing caught in the wheels or in somewhere like the sprocket cover... or something trapped that might cause a harmonic. Is the noise something that aligns with engine speed or road speed?
Just listened to the sound bites in your first post, I've never heard anything like it, it sounds like the belts catching, otherwise a small bearing like the clutch preasure plate bearing, very unusual. Steve
To what belt vibration frequency spec did you tension the belts? The Ducati/Gates belt frequency specification is higher than that for the stiffer ExactFit belts. Any ExactFit belt installed to Ducati’s tension specifications will introduce higher bearing loads and generate more heat from internal friction due to friction. Heat reduces belt service life. It’s clear that ExactFit belts have a different internal construction because the recommended belt tension (frequency) is almost 30% lower that the Ducati specification. How the Exactfit tension spec was engineered or guesstimated is unknown, but there’s no assurance that factors other than noise (i.e., bearing loads, heat build-up, wear, fatigue, tensile strength) were addressed. Excessive ExactFit belt noise resulting from using Ducati’s tension has been noted repeatedly on internet forums – the cure has always been lowering belt tension. One owner described the sound as though a bearing was getting dry. I recommend that you only use OEM (Gates) camshaft drive belts on a Ducati.
Presure plate bearing would have been a good one but my take was that that has been eliminated? I have a similar issue with my 749 although it's intermittent. . Well it goes away sometimes..
At least a 100 miles after, I pulled the alternator cover yesterday, nothing to see so far, rotor, sprag clutch etc next, thanks
