fabio222 Posted March 13 Share Posted March 13 Hey, Just doing some thinking (dangerous stuff, I know) about the differences between the 5th and 6th gen VFRs. So far as I can tell the frame is, basically, the same. I think the swingarm might be different??? The braking setup is a little different I think, although the calipers are the same. The suspension is a bit beefier on the 6th gen (I think....thicker forks maybe?). Now, to the heart of the bike, the engine. I've read that Honda used the RC45 tooling to make the engine for the 5th gen VFR 800 (and this meant there would be no more RC45s as the tooling had to be modified to such an extent that it couldn't be easily changed back). That 5th gen had gear driven cams mounted on the side of the engine. I know the BIG change between the 5th and 6th generation was that the 6th gen did away with the gear-driven cams and, instead, used a conventional chain driven cam setup. The other BIG change was the inclusion of the VTEC system within the head of each bank of cylinders. However, were there any other modifications to the engine between the 5th and 6th gen? Did Honda have to do a full redesign to accommodate the VTEC and cam chain setup? Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted March 13 Member Contributer Share Posted March 13 1 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted March 13 Member Contributer Share Posted March 13 1 hour ago, fabio222 said: Now, to the heart of the bike, the engine. I've read that Honda used the RC45 tooling to make the engine for the 5th gen VFR 800 (and this meant there would be no more RC45s as the tooling had to be modified to such an extent that it couldn't be easily changed back). That 5th gen had gear driven cams mounted on the side of the engine. You're correct... Honda did used the RC45 tooling to make the engine for the 5th gen VFR 800... specifically adding bearing support structure to carry a swingarm pivot... My friend Makota San previous job was Chief Engineer Honda R&D who invented Honda's VTEC... he calls VTEC "his baby" and recalls his boss being super skeptical of the idea working at all... Makota San down on cannery row... 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 13 Member Contributer Share Posted March 13 I think you'll find there are some internal gearbox ratio differences between the 5th and the 6th. The crank is obviously different (gear vs chain sprocket for the cams) but AFAIK the bore and stroke are the same (so maybe rods and pistons?), and I assume the lower crankcase is too. I suspect the alternators are different. I know at least one person has swapped a 5th gen engine into the 6th frame so I presume the engne mounts are the same. So aside from the crank, upper case/cylinders, heads, gearbox, alternator...its all the same? Probably doesn't leave much. 2 Quote Link to comment Share on other sites More sharing options...
Member Contributer mello dude Posted March 13 Member Contributer Share Posted March 13 Aside the obvoius engine differences, the 6th frame has thicker sections and therefore stiffer and also the front forks are 43mm and stiffer as well. That is why some guys have installed a 5th engine in a 6th gen. 2 Quote Link to comment Share on other sites More sharing options...
Member Contributer Captain 80s Posted March 13 Member Contributer Share Posted March 13 2 Quote Link to comment Share on other sites More sharing options...
Member Contributer Lorne Posted March 14 Member Contributer Share Posted March 14 Along with the above mentioned items, other changes included different fuel injectors, ABS brake option, tweaked the Linked Brake system, slightly bigger fuel tank. Throttle response is much worse on the 6th gen, imnsho. I've owned a couple of 3rd gen VFR750s, two 5th gen VFR800s, and a 6th gen - my current ride. From zero to a little throttle the 6th gen is abrupt, not so much fun on tight twisty roads like California's Hwy 1 from the coast to Leggett. Also, my 6th gen has boxier handlebars & footpegs than all of my previous VFRs. It is my first Honda that makes a throttle lock a necessity for long rides. All that said, the biggest difference between the VFR800 generations is how they look and sound, so buy with your heart not your brain. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Popular Post Cogswell Posted March 14 Member Contributer Popular Post Share Posted March 14 3 hours ago, mello dude said: Aside the obvoius engine differences, the 6th frame has thicker sections and therefore stiffer and also the front forks are 43mm and stiffer as well. That is why some guys have installed a 5th engine in a 6th gen. Count me among those . . . swapped mine during the Covid lockdown in '20, was great to have something to do whilst stuck at home. Main things I can think of * 5th gen engine bolts right in to the 5th gen frame - no mods needed. * The "cushion" (Honda's term - I would call it "swing arm mount") that connects the swingarm to the engine is different - requires a 6th gen version to mount to the engine * Yes, the swingarms are slightly different * 5th gen uses remote coils with HT leads, 6 gen is 3 wire COP setup. This is the BIG thing to contend with in doing a swap. I retained COPs. Alternative is to source 5th gen harness and ECU and swap all that over. * 6th gen rads are larger, IIRC 2 additional rows * 5th gen cylinder heads are about 1 1/2" shorter - creates no issues * Shorter heads mean that the cam timing marks no longer appear through the inspection hole in the 6th gen frame (most people don't know why that hole is there). Makes valve adjustments more difficult. Suggest checking valves prior to doing swap * Despite cylinder head differences, throttle bodies are a direct swap * Hoses, thermostat, everything cooling system is interchangeable * If keeping 6th gen electronics, you WILL need a VTEC solenoid connected to the harness or you will get a no-start * 5th gen has a smaller alternator than 03 and up 6th gens. Currently swapping a 6th gen alternator over. * Despite all the similarities in the engine block, water pump, etc, 5 & 6 G alternator covers are different and do not interchange. * As mentioned above 4th through 6th gen gear ratios are different. The 5th gen is under-driven by 1 additional tooth, makes for about 200 rpm or so increase at 70 mph cruise. Barely noticeable. * Power output is indistinguishable. Honda did not add VTEC for power, torque or any other discernable butt-dyno reason. Maybe emissions, marketing, or who knows why. I don't miss it, and I do NOT miss the insanely difficult valve adjustments on the VTEC - the main reason I swapped it out. * Despite keeping 6th gen electronics, there is no VTEC "hit or kick" . There is a subtle change going through 6,800, but if no one knew about it, they would have no idea - nothing like it is stock. * Wheels and front rotors are interchangeable. * 6th gen brake system has 2 proportioning control valves vs 5th gen 1 - bleeding procedure is similar, but different. The linked brakes are plumbed differently between the 2. * 6th gen has available factory luggage * I have seen 6th gen tanks swapped to a 5th gen - doable but requires trimming the 5th gen bodywork in the front where it curves around the tank * 6th gen has available ABS. I've read that about 10% came with ABS, but I know of no documentation of that. On 1 occasion I was glad to have ABS, for me a good addition. * 5th gen has more room under the seat. That's probably more than anyone wants to hear. Owning both, I don't note much difference between them. And now, having one swapped, there's even less. If it weren't for ABS and the factory luggage for long-haul riding, I would probably stick with the 5th gen. However parts are getting harder to find for them, so I don't know how much longer they will be practical for daily or long trip riding. There are still times when I start the 6th gen that I just look at it and still can't get used to hearing that whine from the cams. For my $, that was the best engine Honda ever did or will make. I'm super happy with it. 8 2 Quote Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 14 Member Contributer Share Posted March 14 Well that takes the cake for a comprehensive answer Cogswell! Well done! Quote Link to comment Share on other sites More sharing options...
Member Contributer Lorne Posted March 14 Member Contributer Share Posted March 14 2 hours ago, Cogswell said: That's probably more than anyone wants to hear. Now hold on there, sonny. Us olds love to poke through all the gory details 😉 1 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer mello dude Posted March 14 Member Contributer Share Posted March 14 Great list Cogs! Quote Link to comment Share on other sites More sharing options...
fabio222 Posted March 14 Author Share Posted March 14 Fantastic information here, thanks everyone. I've got a 4th gen and a 6th gen. Both have their merits but I was reading recently about the differences between the 4th and 5th gen but just didn't know as much about the differences between the 5th and 6th gen. Quote Link to comment Share on other sites More sharing options...
Member Contributer Captain 80s Posted March 14 Member Contributer Share Posted March 14 12 hours ago, Cogswell said: * 5th gen engine bolts right in to the 5th gen frame - no mods needed. That is a good start to a project! 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted March 14 Member Contributer Share Posted March 14 I had a '98 5th Gen for several years and 130k miles, an '08 6th Gen for 79k miles and have had 2 Mk2 VFR800X Crossrunners (same engine as 14+ VFR800F) for 50k miles so I do feel qualified to to have an opinion on them wrt each other, even if I'm not that technically minded. The 5th was love within the first 1/4 mile of riding it, that engine! Wow, blew my mind after not riding for a number of years. But it has always looked a bit 'overweight' and bulbous, certainly compared to the 6th Gen and had plenty of issues especially in the early days. I grew to love the looks of the 6th, especially the stacked headlights. It did everything better than the 5th.....except the engine. The VTEC was unrefined, even in an 08 model although fuel consumption was better and the VTEC rush when it kicked in was nice but it would have been nicer to have the smoother torque curve of the 5th without the torque drops preceding the VTEC kick. Handling, braking, looks (in the eye of the beholder), lighting were all better. But the VTEC was a technology looking for a reason to exist. Only introduced to meet emissions regs and it threatened to ruin a great engine. Fast forward to the 2014 800F / 2015 800X and you have the best 800 of all imo. Honda have refined the VTEC engine significantly and the rest of the bike is as much an upgrade as it was from 5th to 6th Gen. I'm sure any 800F owners would agree as I've only ridden the 800F once but I have absolutely loved my 2 800X's and wouldn't swap them. Having said all that, I do own an '01 5th Gen too. The VFR1200 is the best VFR ever made. 😉 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer bmart Posted March 15 Member Contributer Share Posted March 15 I have very little to add. My 5th gen is superb, as was the 5th gen before it. The 6th gen I rented nearly got thrown in the ocean the VTEC was so bad. In my mind, there's no comparison. Quote Link to comment Share on other sites More sharing options...
fabio222 Posted March 15 Author Share Posted March 15 I wonder were sone VTECs worse than others? On a per-bike basis. One 2003 model feeling different to another 2003 model. It happened with rear suspension/weaving issues on Pans of that era. Quote Link to comment Share on other sites More sharing options...
Member Contributer tsmitty Posted March 15 Member Contributer Share Posted March 15 Did their motorcycle VTECs back then actuate a larger cam profile or valving? Quote Link to comment Share on other sites More sharing options...
Member Contributer Skids Posted March 15 Member Contributer Share Posted March 15 1 hour ago, fabio222 said: I wonder were sone VTECs worse than others? On a per-bike basis. One 2003 model feeling different to another 2003 model. It happened with rear suspension/weaving issues on Pans of that era. Yes, anecdotally from rider reports. 06+ models introduced the staged VTEC points, approx 6800rpm on acceleration, 6400rpm on deceleration. They could still be quite harsh though. Quote Link to comment Share on other sites More sharing options...
Member Contributer bmart Posted March 15 Member Contributer Share Posted March 15 In my business we call VTEC on a bike a solution without a problem. You guys can have and love them, but I'm sticking with VFR tradition. lol Quote Link to comment Share on other sites More sharing options...
fabio222 Posted March 15 Author Share Posted March 15 36 minutes ago, bmart said: In my business we call VTEC on a bike a solution without a problem. You guys can have and love them, but I'm sticking with VFR tradition. lol Go one better. Have both 😂. I see it as a typical Honda technological willy-waving. "We believe we can do this so we are going to do it" - same with oval pistons, same with linked brakes, same with VTEC. Quote Link to comment Share on other sites More sharing options...
Member Contributer Captain 80s Posted March 15 Member Contributer Share Posted March 15 7 minutes ago, fabio222 said: I see it as a typical Honda technological willy-waving. "We believe we can do this so we are going to do it" - same with oval pistons, same with linked brakes, same with VTEC. Of those three answers to questions no one asked... one is cool. Quote Link to comment Share on other sites More sharing options...
Member Contributer BusyLittleShop Posted March 15 Member Contributer Share Posted March 15 In my learned opinion VTEC (Vacillating Torque Engine Compartment) was successful on heavy autos but it's been 50 / 50 when applied to lighter weight bikes because of the unwanted bump in the power ban... 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Lorne Posted March 15 Member Contributer Share Posted March 15 I've wanted to know, like forever, how a 6th gen would run if the VTEC was forced on. The manual is vague on the specifics but it seems that the ECM only cares about engine rpm and coolant temp to open or close a spool valve. But I am just daydreaming... 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 15 Member Contributer Share Posted March 15 9 hours ago, tsmitty said: Did their motorcycle VTECs back then actuate a larger cam profile or valving? VTEC on the bikes activates 4 valves per cylinder at higher revs and 2 vavlves at lower revs. I think the earliest iteration had asplit forked rockers and a locking pin slid across to lock the two valves together. The VFR system stuck with the shim under bucket direct valve actuation of earlier models but the VTEC valves have special buckets that also use a locking pin activated by hydraulic pressure to connect to the valve stem. It sounds terrifying but clearly isn't as mechanically deadly as I would have thought. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted March 15 Member Contributer Share Posted March 15 8 minutes ago, Lorne said: I've wanted to know, like forever, how a 6th gen would run if the VTEC was forced on. The manual is vague on the specifics but it seems that the ECM only cares about engine rpm and coolant temp to open or close a spool valve. But I am just daydreaming... I also wondered what would happen if you used the non-VTEC buckets and valves in the VTEC positions so 16 valve operation is constant. It appears the cam lobes are the same on both VTEC and not VTEC valves. Probably not worth the effort. Quote Link to comment Share on other sites More sharing options...
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