Berto46 Posted June 25, 2015 Share Posted June 25, 2015 Hello everyone, new forum member here. Recently bought a 6th Gen VFR800 abs. I asked the previous owner if the valves have been checked which he said as far as he was aware, yes ( no paperwork though). I haven't had a chance to look over the bike as yet with the exception of all the fluids/ tires/ chain, nuts, bolts etc. I can hear a very distinctive tap tap tap on idle regardless if the clutch is in or out (sounds very deep in engine). There is also quite a smell of unburnt gas coming from exhaust. Not only that, there is also quite a few pop (like backfire) when off the gas revving down (in gear). I have owned a 6th Gen before but never had this problem so know there isn't quite something right. Wondering if any of your pro's out there would help me diagnose the issue. I can and will post to all replies as I want this bike to be faultless and go on a long cross-country Canada tour. Thanks in advance! Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted June 25, 2015 Member Contributer Share Posted June 25, 2015 Some basic info would be helpful - miles or km's on the bike, mods, etc. Here's a post from 3 days ago regarding fuel smell in the exhaust with some good info. http://www.vfrdiscussion.com/forum/index.php/topic/81394-help-with-heavy-fuel-smell-from-exhaust/ As for the tapping sound, it wouldn't shock me if it's the cam chain tensioner(s). There are a number of posts such as this one about CCT's and their replacement. http://www.vfrdiscussion.com/forum/index.php/topic/76-cam-chain-tensioner-without-throttle-body-removal/ A video would probably be helpful and it's needed anyway, since on your 1st post, no picture = no bike! Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 25, 2015 Member Contributer Share Posted June 25, 2015 Welcome and yeah a video would really help. Roll On .. Link to comment Share on other sites More sharing options...
Lint Posted June 26, 2015 Share Posted June 26, 2015 My guess is CCT as well. I have to replace mine, my front is bad. Here is a video of what mine sounds like. Terrible video, but it captures the sound. I don't have an external mike, so I had to move my phone around. Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted June 26, 2015 Member Contributer Share Posted June 26, 2015 Technically speaking backfiring on deceleration is generally theresult of a lean condition in the fuel system... What occurs in a leanmixture is it fails to ignite consistently... The result is unburntfuel migrates into the exhaust pipes... As next engine cycle doesfire... those unburnt gasses are ignited down wind in the exhaustpipes... pop you hear the sound of backfire.You could eliminate the possibility of a intake or exhaust leak. Checktorque all the intake clamps and exhaust bolts... Some people checkthe intake system by starting the motor and spray a little carbcleaner around the intake manifold. If the RPM's increase then youhave a leak... Link to comment Share on other sites More sharing options...
Auspanyol Posted June 26, 2015 Share Posted June 26, 2015 Re backfiring: First thing to try is check ur air filter and then syncronize your starter valves. Aftermarket pipes? Mine was doing that on deceleration and idle which I noticed after installing Laser X-treme pipes. I can't prove if the condición existed before and the fact I could now hear it w the aftermarket pipes... But I did sync starter valves after installation and was fairly certain I botched it on one cylinder. Hooked carbtune back up and Bingo Link to comment Share on other sites More sharing options...
Berto46 Posted June 27, 2015 Author Share Posted June 27, 2015 Hey Gents, Thanks very much for the replies so far. Still using the bike as a daily rider commuting to and from work. Done a LOT of research so far on the CCT and suspect it could be that. Especially now that I heard the video from Lint which is almost exactly the same. From what I have read also, from the link by Cogswell (thanks) its best to just replace the CCT with a new OEM instead of playing around with it and the key? I'm sure if the internal spring is screwed, the key isn't going to do anything. I would rather spend $120 and do it myself. So far, as far as I'm aware, there are no upgrades to the bike, no aftermarket pipes (although it does sound like baffles are removed), not sure about air filter or the pair mod? Is there an easy way to sync starter valves? I'm sure I saw a youtube video on this but has a bank of 4 vacuum/pressure guages for settings? I could be wrong on this, seen so many youtube videos my head is spinning lol. I will be doing the CCT as soon as its ordered and arrives but plan on ripping apart air box, changing oil, plugs, coolant, pads (needed) and other stuff. Last question is how do I truely know if the valve clearances are true? I wasnt convinced by the answers of the previous owner. Thanks again. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted June 27, 2015 Member Contributer Share Posted June 27, 2015 You would have to tear it down and do the valve check to truly know. Roll On .. Link to comment Share on other sites More sharing options...
Auspanglish Posted June 27, 2015 Share Posted June 27, 2015 the 4-way carbtune is a good way to go... the video you saw was surely Kaldek... with his Limited Edition 2002 6th gen (emphasis on "Limited")... his vacuometer or manometer or whatever you wanna call it, had a bank of 4 analogue meters... the one from an earlier message by Auspanyol (yeah, that's my alter ego)... is a column style that used to use mercury but now they are some sort other undangerous material... 80 bucks... It's not a difficult task just fiddly. I did not bother adjusting the idle to 1200 with a tach or multimeter or pc... I just synced em up and then set the idle... Kaldek's vid: https://www.youtube.com/watch?v=1sj33NXnm1c Also Kal blocks of the flapper vacuum hose. I don't, since I didn't see anything in the workshop manual. I just followed the manual except for controlling the idle during the procedure as I said. Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted June 28, 2015 Member Contributer Share Posted June 28, 2015 Last question is how do I truely know if the valve clearances are true? I wasnt convinced by the answers of the previous owner. Thanks again. 500 rpm idle check... Start the engine and let it gain operating temp... take the idle adjustment and begin lowering the rpms... you're noting at the lowest rpm the bike will run... if the engine ticks over at 500 rpm or less... there's a lot of things right about the internal condition... things like compression and valve adjustment... Link to comment Share on other sites More sharing options...
Berto46 Posted July 29, 2015 Author Share Posted July 29, 2015 Thanks once again for all the replies. I will be taking a "voice note" on my phone tomorrow to see if anyone can diagnose. Leading towards the CCT given some of the posts already but best to confirm. Also having trouble starting at times. Previous owner installed a volt meter on the dash but sometimes drops to 0V when starting. Relay maybe? Still have to do my first full teardown of the bike but at least if I can get everything in place, I can order all the parts and hit it in one shot. Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.