adamv Posted November 29, 2014 Share Posted November 29, 2014 Hi, I noticed today after a "spirited" ride in 30 degree weather a strange "donk" sound coming from the front of my bike when I was riding slowly. (Around 30kph maybe). The best I can describe it is like when you plug in a USB device into a windows computer and it first recognises it with a 'donk' sound - that's probably similar - except it was making a double donk sound. ie: donk - donk...... and then a pause for a while, and then it did it again. I'm not sure if it's just something contracting or expanding in the heat, or something more sinister. I had a look at the front of the bike - and I identified that the wheel was still there with pressure in the tire. That's about as far as my mechanical skills go I'm afraid. :-) Does anyone have any idea what it might be? TIA Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted November 29, 2014 Member Contributer Share Posted November 29, 2014 this could be your fork "bottoming out" aka reaching the full limit of compression.. or if it happened while giving it a lot a gas quickly.. "topping out" aka having the forks extend to max range .. Link to comment Share on other sites More sharing options...
adamv Posted November 29, 2014 Author Share Posted November 29, 2014 Now that's a thought. I guess it does sound something similar to what that would. I just sat on my bike then tried bouncing it around and couldn't get the sound. (It's been in the garage cooling down for the last few hours). I wonder if it's got to be pretty warmed up to do it. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted November 29, 2014 Member Contributer Share Posted November 29, 2014 it takes a LOT to to make the fork bottom.. the bouncing is NOTHING compared to hitting a 1 inch bump at 90 mph. let alone what you where running over down there.. now.. a few things com into play.. your weight the speed and how your forks are set up.. how old the fluid is etc etc,, its not the temp of the air. or the motor.. trust me on that. the samer bump on the highway bottoms my fork out at freezing and at 100*f Link to comment Share on other sites More sharing options...
Beck Posted November 29, 2014 Share Posted November 29, 2014 HIghly unlikely,....but maybe a broken spring? You might also want to check the linkages on the linked brakes system on the left side fork leg for anything loose that could cause the noise.. Link to comment Share on other sites More sharing options...
adamv Posted November 29, 2014 Author Share Posted November 29, 2014 Thanks guys. As previously mentioned - I highly doubt it's bottoming out as it was happening at low speed on a flat and level surface. Where would I start looking for a broken spring? Is this part of the suspension setup? I'll also have a look at the linkages - thank you. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted November 29, 2014 Member Contributer Share Posted November 29, 2014 Check the top of your front fender and make sure nothing coming in contact with it. My horn came loose and was hitting the top of the fender. Link to comment Share on other sites More sharing options...
The Phantom Posted November 29, 2014 Share Posted November 29, 2014 Maybe steering head bearings out of adjustment or worn out? Link to comment Share on other sites More sharing options...
adamv Posted December 2, 2014 Author Share Posted December 2, 2014 Thanks for the suggestions guys. I think I've resolved myself to the fact that I probably should go and take it to a mechanic to look at. He did mention the possibility of steering head bearings on the phone, so that could well be a possibility. Should hopefully know for sure later this week. Cheers. Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted December 2, 2014 Member Contributer Share Posted December 2, 2014 When interpreting the dynamics of motorcycle stability, it is usefulto understand that if your steering head bearings are too tight thebike will weave and not seek it own center... and if you're steeringhead bearings are loose you'll notice a pronounce clunk duringbraking...I don't teach the torque method rather I raise the front wheel off theground and tighten the steering head bearings until the bars lock thenI back off the nut until the bars free wheel with a slight drag...with this method you find that sweat spot and avoid over tighteningand under tightening even if you upgrade to taper roller bearings... Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted December 2, 2014 Member Contributer Share Posted December 2, 2014 Plus one on what Larry said. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted December 2, 2014 Member Contributer Share Posted December 2, 2014 One other possibility would be the fork damper rod coming undone from the fork cap; I'd imagine that in addition to a noise, this would feel pretty awful with a loss of damping in one leg. The idea of a loose horn hitting the mudguard sounds pretty likely to me. Link to comment Share on other sites More sharing options...
JimGregory Posted December 2, 2014 Share Posted December 2, 2014 My "donk" in the front end was a missing rubber bushing on the right side brake caliper slider. Make sure there are bushings on those sliders. No mechanic needed to check it or repair it. Actually it drove me nuts for the first week of my ownership. I ASSumed it was something inside a fork leg. Link to comment Share on other sites More sharing options...
adamv Posted December 3, 2014 Author Share Posted December 3, 2014 Thanks so much for the replies guys - can't get over how friendly this forum is... I've found and checked the horn. All looks fine there from what I can tell. I tried to look for bushings (after google imaging "bushings" to find out what they are but I'm still not sure what I'm looking at. (I wasn't really exaggerating when I said in my OP that my limits to mechanics was seeing that the front wheel was on and tire pressure OK ) - but even after googling, I'm not sure what I'm looking at with the front brakes. Likewise with the steering head bearings. I can't see anything obvious missing - but that really doesn't mean much coming from my uneducated eyes. Bike will be going into mechanics soon for a quick check. I didn't notice the bike feeling any different when I was riding it - it felt fine. (But then again, my experience with riding a road bike isn't much better than my experience with mechanics - it's all very new to me, so if somethings changed that's less than really obvious I may not pick it up either). I've just never noticed the noise before and there wasn't anything I was doing that I could pin it down to (like occurring when hitting a bump, or braking, etc). If anything it concerned me more because it was occurring when the bike was at it's most stable and I was doing nothing except riding slowly. Thanks again. If the mechanic finds something I'll be sure to let you all know. (Regardless of how embarrassing it might be) :) Link to comment Share on other sites More sharing options...
adamv Posted December 4, 2014 Author Share Posted December 4, 2014 The mechanic wasn't able to find anything that might have resemble what I'm hearing. Good news is that everything looks fine. Still got me wondering what on earth it could be. When I heard it again today, it almost sounded like a horn was going for 1/100ths of a second. (Just started to vibrate), but the pitch seems wrong for the VFR horn. Maybe I should just try and ignore it like I try and ignore those voices in my head that just say 'faster, go faster'. ;) Link to comment Share on other sites More sharing options...
JimGregory Posted December 4, 2014 Share Posted December 4, 2014 I have been ignoring the voices for 45 years. For the most part! Go easy. So OK you are not a mechanic. Maybe you are a recording engineer? Try to catch the noise with a recording? This is like ghost busters. Link to comment Share on other sites More sharing options...
Member Contributer gll429 Posted December 4, 2014 Member Contributer Share Posted December 4, 2014 Maybe I should just try and ignore it like I try and ignore those voices in my head that just say 'faster, go faster'. ;) WAIT !!?? :excl2: WHAT !!??? :excl2: you mean we can IGNORE THAT VOICE ????!!!!!??? why doesnt anyone tell me these things??? oh, right... they did... " go slow, drive safe" i ignored THOSE voices.. Link to comment Share on other sites More sharing options...
Member Contributer LangoPTC Posted December 6, 2014 Member Contributer Share Posted December 6, 2014 Seen on a T-shirt... "I know the voices in my head aren't real but sometimes they have some pretty good ideas." I'm assuming you (or the mechanic) have made sure all fasteners on the bike are properly torqued/snug? Link to comment Share on other sites More sharing options...
adamv Posted December 9, 2014 Author Share Posted December 9, 2014 Thanks. I trust the mechanic. (Small town and he has a brilliant reputation). I heard it again the other day - it may just be part of the normal running of the bike I've never noticed before. It's almost 'liquid' in tone (like a water drop) - but not quite. I'm going to have to figure out a way to record it. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted December 9, 2014 Member Contributer Share Posted December 9, 2014 Maybe I should just try and ignore it like I try and ignore those voices in my head that just say 'faster, go faster'. ;) WAIT !!?? :excl2: WHAT !!??? :excl2: you mean we can IGNORE THAT VOICE ????!!!!!??? why doesnt anyone tell me these things??? oh, right... they did... " go slow, drive safe" i ignored THOSE voices.. That's your new wife ? Link to comment Share on other sites More sharing options...
adamv Posted December 24, 2014 Author Share Posted December 24, 2014 OK - Coming 1 step closer to finding out what's going on. Before I said that it was happening at low speeds. It seems that once the bike is hot, if I have the bike idling, and I just very gently blip the throttle (the slightest of turns) I can make the strange noise occur. I'm guessing I was noticing it at low speeds because the throttle is more sensitive at low revs / speeds and it may have been causing the bleep / donk / whatever sound I'm hearing. Doesn't happen when the bike is cool - just when it's warmed up. Sound appears to be louder the hotter the engine. Does this raise any ideas? Cheers Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted December 25, 2014 Member Contributer Share Posted December 25, 2014 PAR valves maybe. Link to comment Share on other sites More sharing options...
Member Contributer MarkDetroit Posted December 25, 2014 Member Contributer Share Posted December 25, 2014 I bet it's the flapper valve in the top of the air box. Vacuum actuated. Some folks choose to plug the vacuum line anyway but i have found my bike hesitates less when i keep it connected and with it operating as intended. As a test just pull the air line and plug the line (maybe with a golf tee or small steel ball) temporarily. Link to comment Share on other sites More sharing options...
adamv Posted December 25, 2014 Author Share Posted December 25, 2014 Thanks guys. Vacuum actuated valve would probably sound plausible for the type of sound I'm hearing. If I can work it out what I'm looking at I'll try testing it when it happens again. Thanks! Link to comment Share on other sites More sharing options...
Auspanglish Posted December 25, 2014 Share Posted December 25, 2014 It's the flapper valve on the airbox and it's completely normal. Ride on... If you want to see it, undo the two bolts that hold the Front of the fuel tank and lift it up (have to Remove the seat so it can pivot upward) and Prop it up with Something about 30 cm Long. There you''ll see the Black plastic Airbox with a copper Coloured Donut without the hole shaped vacuum valve. The Flap Which opens and shuts with a clonk is at the Front of the Airbox Link to comment Share on other sites More sharing options...
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