Member Contributer tsmitty Posted March 15 Member Contributer Share Posted March 15 If the vtec was active all the time mho the engines wouldn't run on the bottom. Back when I had a job at a place called Transportation Research Center (a testing facility for Honda R&D North America) I got to take the vtecs apart post testing (the Japanese associates called this "zimbara") those engines used the hydraulic pin to activate a second follower on a more aggressive profile lobe on the cam. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer tsmitty Posted March 16 Member Contributer Share Posted March 16 2 hours ago, Terry said: 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. took a minute to wrap my head around that one... Love to take one of those apart...haha takes titanium keepers to the next level Quote Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted March 22 Member Contributer Share Posted March 22 On 3/15/2024 at 1:53 PM, 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 can't say for sure, but it appeared to me that all one needed to do would be to send key-on current through the VTEC solenoid full time to have all 4 valves operating continuously. If the ECU balked at that, then a workaround would be to add a second solenoid plugged in to the ECU, and it would "think" all was normal while the installed solenoid would make the VTEC valves operate continuously. I do agree that VTEC on these bikes was an answer searching for a problem. Strangely, when I checked my VTEC valves, the *all* were tight. That made no sense to me. I re-ran the check several times. Finally, I had an aviation mechanic / Honda bike lover come over and handed him the inspection procedure and pointed at the tools and said "tell me what you think". After about and hour * he said "all your VTEC valves are tight". That was when I began searching for a GDC replacement. Quote Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted March 22 Member Contributer Share Posted March 22 On 3/15/2024 at 5:00 PM, tsmitty said: took a minute to wrap my head around that one... Love to take one of those apart...haha takes titanium keepers to the next level IMHO they're a PITA. It is interesting how it works - and it does - but it seems mostly pointless comparing how that motor operates compared to a 5th gen. It doesn't seem to accomplish much, if anything. It could be different if this iteration of VTEC had variable valve timing, but this is just a light switch - either the 8 VTEC valves are working, or they're not. Quote Link to comment Share on other sites More sharing options...
Member Contributer tsmitty Posted March 22 Member Contributer Share Posted March 22 12 minutes ago, Cogswell said: either the 8 VTEC valves are working, or they're not. I personally would explore mechanically jamming that "locking pin" so you don't have to play with the electronics, thats if the system won't throw an error code. Quote Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted March 23 Member Contributer Share Posted March 23 On 3/13/2024 at 5:40 PM, Cogswell said: 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. This was the "what have I done" moment, after the VTEC was lowered from the frame with the 8,000 mile 5th gen motor waiting on the pallet. The cam cover is removed b/c I had already been in there adjusting the VTEC valves and it also gave me the extra clearance needed to clear the frame once lowered on the jack. Once it was back together and running, going for its first short ride around the block left me barely believing it was actually working. I read where others that have done this sit the engine down on block(s) and then lift the frame off and roll it away like a wheel barrow, leaving the engine behind. On top of the 2 step ladders is a thick wooden beam and ratchet straps. Either way works, this is just mine. Clearly this is quite invasive surgery, but very doable for any determined DIYer. Like any project, bag & tag fasteners, label, stay organized and torque to spec and you'll be good. 4 Quote Link to comment Share on other sites More sharing options...
Member Contributer mello dude Posted March 23 Member Contributer Share Posted March 23 Cogs -- Would love to see a build it thread of your 5/6th conversion.. Quote Link to comment Share on other sites More sharing options...
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