Samxboy Posted February 12, 2023 Share Posted February 12, 2023 Might be a strange question but I'm new to the VFR800, having acquired a 2016 crossrunner quite recently. Apart from really lousy low speed running the bike also makes a loud 'thwack' noise ( for want of a better description) in the exhaust muffler / collector box area after revving the engine in neutral. Never heard anything like it previously in any bike so it sounds uniquely weird to me. Thought I saw someone else raise this question before but can't find any trace. Anyone discovered what this is, assuming it's a common trait? Link to comment Share on other sites More sharing options...
Member Contributer bmart Posted February 12, 2023 Member Contributer Share Posted February 12, 2023 A video of the area with audio might help us help you. Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 12, 2023 Member Contributer Share Posted February 12, 2023 I'm on my second Crossie and I've not heard of symptoms like that before. A video/audio would help. A Crossrunner in Florida? I didn't think they were sold in the US, what's the story please? Link to comment Share on other sites More sharing options...
vfrgiving Posted February 12, 2023 Share Posted February 12, 2023 Clogged, damaged, or loose catalytic converter honeycomb? A mechanic's stethoscope held up to the collector box and listen while you rev the engine may narrow in on the problem. Link to comment Share on other sites More sharing options...
Samxboy Posted February 12, 2023 Author Share Posted February 12, 2023 5 hours ago, Skids said: I'm on my second Crossie and I've not heard of symptoms like that before. A video/audio would help. A Crossrunner in Florida? I didn't think they were sold in the US, what's the story please? The bike is in the UK. I'm currently residing in the US. I did find the original post where this was mentioned ..... The link to the video didn't work for me but by the description it must be the same thing. The general consensus was the PAIR system, working as it should....if that's so why aren't you guys hearing it, assuming your PAIR systems are still intact? There is however a broader issue I'm facing and this maybe connected?? My concern is that ever since owing the bike ( Aug 22) the slow speed running has been terrible. Took it back to the dealer and they finally did a starter valve balance. ( Bike is a 2016 model with 17k miles) This helped but every now and then it runs rough again as though 'something' is sticking? Is it the PAIR system working overtime?? Should I just block it off? When I'm back in the UK (April) I'm also going to take a look at the injector assembly to see if there is something amiss with the starter valves...My thinking here is that when I did replace the original air filter which was absolutely filthy it was clear that there had been some water ingress into the front left throttle body causing some corrosion. Maybe that is causing the starter valve to get sticky and hence the poor low speed running. Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted February 12, 2023 Member Contributer Share Posted February 12, 2023 Need video & audio but mine didn't make noises I'm concerned about. Link to comment Share on other sites More sharing options...
Samxboy Posted April 11, 2023 Author Share Posted April 11, 2023 Just thought I'd update you. Arrived back in the UK and started working through the probable causes. I suspected a fault in the PAIR system that would allow air to continue to flow through the PAIR system long after it should have stopped. The additional air leading to detonation in the exhaust system causing the thwacking noise. Simply blocking off the air feed pipe starved the PAIR system of air and stopped all the noise in the exhaust system. The mod has also removed most all the low speed running issues I have experienced. It's probable that the solenoid had stopped working long ago..... Link to comment Share on other sites More sharing options...
Member Contributer Captain 80s Posted April 11, 2023 Member Contributer Share Posted April 11, 2023 THIS ^ is one reason why you eliminate PAIR. On my 90's VFRs and ST1100, it is a U.S. only system. On those Euro models the heads aren't even machined for the hard pipe fittings. Everything else is the same... airbox, carbs, exhaust. So... not designed for it or needed in Honda's own opinion. The diaphragm units in my 27K mile ST1100 were goo and the decel popping was terrible. Without it, runs perfect. I would be so thrilled for this to start happening in the middle of a trip. That time bomb clutter can go in the garbage imo... after I harvest all the tubing, pan screws and bolts. Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted April 11, 2023 Member Contributer Share Posted April 11, 2023 PAIR delete is one of the easiest and best mods you can do to the VFR800. My 01 has been done and it is so smooth and easy at lows revs, I am unusually surprised at how much difference it made. Link to comment Share on other sites More sharing options...
Member Contributer bmart Posted April 11, 2023 Member Contributer Share Posted April 11, 2023 Is there a link to this so monkey (me) could do it? I have a few bikes I'd like to do it to including the '98 and '00 VFRs. Thanks! Link to comment Share on other sites More sharing options...
toreckman Posted April 11, 2023 Share Posted April 11, 2023 52 minutes ago, bmart said: Is there a link to this so monkey (me) could do it? I have a few bikes I'd like to do it to including the '98 and '00 VFRs. Thanks! Here's a video that helped me - Also a good guide here - Link to comment Share on other sites More sharing options...
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