GreginDenver

This thread keeps reminding me of another thread from a couple years back. There was another owner (of a 5th Gen, I think) who had a "misfire when warm/hot" situation, and after a lot of searching and trouble shooting he discovered that one of the coils had a crack in it's plastic covering which was affecting the coil's ability to fire the spark plug (apparently the crack in the coil cover was allowing a partial grounding of the coil field to occur). I can't remember which VFR forum this thread was on, I searched around a bit but couldn't find it. Have you done a thorough/close visual inspection of the bike's ignition system, to include the coils?

As I am naturally unafraid of re-wiring the electrical wiring in cars and motorcycles, the question I would be asking myself is... If the '86 trigger wheel is discontinued and only the '87 (and onward) trigger wheel is available, how hard would it be to fix the issue by working from the other end of the system by substituting/retrofitting an '87 ignition control box on an '86 VFR? The question would be: How much of the bike's wiring harness was changed from the '86 model to the '87 model? If the only change was the obvious switch from analog trigger wheel to digital trigger wheel for ignition control then swapping in both an '87 trigger wheel and the matching '87 ignition control box would be possible. I can tell you from experience that these old-school ignition control boxes (on 1980s carbureted bikes) often only have 6 or so (maybe up to 10) inputs (wires). It wouldn't be too hard to track down all of the inputs to see if you could make the swap (you might have to "re-pin" the connector to bring in all the correct inputs to the correct placement on the ignition control box).

No, both of my FI project bikes are "batch" injected. I am using an Arduino to sample a MAP sensor attached to each throttle body, the Arduino then sends the lowest value to the MicroSquirt via a DAC. This effectively simulates the vacuum stability of having a large central intake manifold. This setup isn't my creation, a guy named Dennis who lives in Germany thought it up and he was nice enough to help me copy it. If I remember correctly Dennis tried sequential on his 750 race bike but it didn't deliver any improvement in performance (for a lot of extra effort) which I think is a common conclusion people reach when they're dealing with a motorcycle engine. The RPMs are so high it makes a mockery of the attempt to impose the higher order that is sequential.

But here's a question: Have you done the "Flapper Mod" on your 5th Gen VFR800? If the answer to that question is "yes" then we should not discuss anything vehicle-related (it just won't be productive).

I have worked with MegaSquirt/MicroSquirt fuel injection conversions since 2005. Yeah, I know there are many ways to combine parameters to achieve good FI. Yes, I think Honda PGM-FI is a bit old-school compared to modern day FI ECUs but it got the job done for a whole bunch of Honda products for a lot of years.

Actually... Chapter 21 of the VFR800 Service Manual says... And then Chapter 21 goes on to say...

While you're learning stuff... the explanation for why your bike was still able to run pretty well with a MAP sensor problem is contained in Chapter 21 of the Service Manual. In this magical chapter all is revealed, including the fact that the ECM (Honda PGM-FI) only uses the MAP sensor during low throttle openings (i.e. small throttle position sensor opening angles). As you wind on more throttle the ECM switches modes to a pre-programed fueling method (usually referred to as Alpha-N). This mode does not reference the reported MAP sensor value because at higher RPMs small engines (like motorcycle engines) deliver wildly chaotic MAP sensor values.

not to thread-jack, but... I think it's worth addressing the unavoidable, engineered-in weakness that naturally comes as part of a "side-radiator" design. This is something I've been thinking about for a long time (whenever I find myself thinking about how hot the VFR800 runs). The built-in problem with side-radiators is you have to move coolant from one side of the bike to the other. You have no choice but to run a large diameter tube full of coolant right past the headers for cylinders #2 and #4 (less than about 1.5 inches). I don't know what the math of this situation is like, but you know there has to be substantial radiant heat-energy transfer in this area. I've been thinking of putting heat protection on this coolant tube since I first rode my 5th Gen in summer heat.

I'd like to imagine plasma-transferred wire arc (PTWA) technology (like Ford is using in their Mustangs) someday, somehow "trickling down" to the aftermarket world because PTWA gives very good performance and wear to a cylinder liner.

Those of us who ride the VFR800 know how heavy the bike is, and how just a single moment of brain-fade can allow that weight to catch you out and put the bike on the ground. I had my moment two years ago when I pulled into a do-it-yourself car wash in Huntsville at the end of a 3-day ride from Denver to Alabama. I'd ridden through quite a lot of bugs and such, wanted to clean the bike up. Ended up with the beast on its right-hand side. I was tired, didn't realize my situational awareness was at a pretty low point. Wow, if the guy in this video can ride like that all the time, jumping on and off, balancing that heavy bike, then my hat is off to him. (but if I were in his shoes I'd definitely pick my routes carefully, if you tossed in something like a steep hill or potholed/poor condition pavement in addition to a stop light things easily could get out of hand).

Here's my vote for you to restore/keep the airbox flapper mechanism in its original configuration... Why? Because there are two types of people in this world: There are those who understand that air acts like a fluid, and there are those who do not understand. Can you guess which group does "the flapper mod" on their 5th Gen VFR800s? On the 5th Gen engine (being a non-VTEC engine) the dual-track intake system has a definite function, and even better than being functional it (the dual-track intake system) makes great sounding noise. You (the rider) can hear the bike's airbox/intake horns/throttle body hit a hard resonance as the RPMs go over 7,000. Then the airbox flapper opens up and the resonance noise happens again at about 10,000 RPM.

So what about your bike's 23-year-old Fuel Pressure Regulator? When I purchased my two 5th Gen VFRs (one is a '99 and the other is a '01) I replaced the fuel pressure regulators, because they were about 20 years old. Because I replaced the Fuel Pressure Regulators on my VFR800s immediately after taking possession of the bikes (as part of my "new owner" maintenance efforts) I haven't had to deal with the problems/symptoms that a failing Fuel Pressure Regulator might cause, but the odd conditions you've described could be FPR related. So this is just a thought: I wonder which one of the engine's 4 cylinders would be most affected if the Fuel Pressure Regulator was allowing gas to pass into its vacuum line? Cylinder #3 maybe? But even if your bike's FPR hasn't begun to fail it's still 23 years old, you should go ahead and replace it. I'm pretty certain the Honda engineers viewed the bike's FPR as a "consumable item". Good luck with the problem.

This is great, it's like a 1970's disaster movie where a pilot on the ground is talking on the radio to a flight attendant who has to land a damaged Boeing 747 at night on a short runway because the pilots are both dead.

One big problem with owning a 21 year old bike is that the maintenance honeymoon is well and truly over. 5th Gen VFRs are great bikes IF they're kept in good shape as they age. The fuel pressure regulator is 21 years old, how long is it supposed to last? I didn't wait around to find out when I purchased my '99 5th Gen. Likewise, the fuel filter is 21 years old... And all the rubber seals that hold the fuel injectors are old and hard (they might still look good but after 21 years they're not what they used to be) And what's the mileage? Is the engine overdue for a valve clearance check and adjustment (as necessary). Have the starter valves been synchronized recently? Your hard-cold-start problem could be due to one particular thing, or it could be due to the interrelated effects of several minor issues.

You can also see from the drawing that in both cases (both the 180 degree crankshaft engine and the 360 degree crankshaft engine) the primary headers are on cylinders that provide the widest possible spacing of exhaust pulses into both the primary "Y"s and into the final merge (the "collector"). This is how you arrange things for good gas flow through an exhaust system.

Yes this is still happening. It appears that we (those of us already in with deposits on the current group-purchase) have stalled out below the number of header systems required for an order to go forward to production. So if you come in and add yourself to those who've placed deposits we'll be closer to "go!".

Sounds like you made a good purchase, 1 owner and only 15,000 miles, that's the way to start out. And the VFR engine is very well-built and durable but the truth is that the rest of the VFR, its electrical system, its fuel delivery system and all are just standard Honda gear. By purchasing a 22 year old motorcycle you've put yourself in the position of having to do "old motorcycle" maintenance and refurbishment. If you're not into old motorcycle maintenance you may have made a mistake. If you've been a motorcycle guy long enough you've met "that guy" who loves motorcycles, loves to ride, but somehow knows absolutely nothing about maintaining them. With a 22 year old motorcycle you can't be that guy. My personal standards always lead me to give "new-to-me" old motorcycles a thorough going over. Here's where I went with my '99 after I purchased it in 2016.

I agree that it's hard to find a replacement (or alternative) to a V-4 engine. And yes, I agree that a crossplane parallel twin is a bit of a far cry from the V-4 experience. But here's an in-between engine candidate, the Triumph "T-plane" triple. Surprisingly the T-plane triple engine has exactly the same firing order as the VFR engine, just without the 4th cylinder. The T-plane fires like this: 1-0-3-0-0-2-0-0- and it sounds a lot like the VFR's V-4 engine. At the end of this video there's a few seconds of full-throttle T-plane 3 cylinder acceleration to listen to. You'll be surprised how much it sounds like a VFR V-4 engine. https://www.youtube.com/watch?v=Woh023WrZlQ

Yes, I agree that the length of the headers (relative to one another) is very nearly the complete solution (something around a 90% solution) and as a result constitutes the majority explanation for the odd-seeming instructions for the Starter Valve Sync procedure. But the design element that keeps header length from being a pure, complete, 100% solution is the VFR's irregular V-4 cylinder firing order, because it (the VFR's irregular firing order) causes localized, cylinder to cylinder changes/differences in gas velocities and resultant "scavenging" and flow of gases from individual cylinders. The VFR headers (whether 5th Gen or 6th Gen) are a "tri-Y" design, so you have to consider the gases from each of the 4 cylinders, the order in which they are fired, the lengths of the individual headers from each cylinder, and the order in which the exhaust pulses arrive at the "Y" merges within the header system. I'm not college-trained in Fluid Dynamics (as high speeds gases act like fluids), so I can't give an absolute fact analysis of the situation. But maybe we could get to a better understanding with a side conversation, I'm open to hearing opinion and analysis that dissects/examines the timing and effect of the VFR's 1-0-3-0-0-2-0-4- firing order and how that timing interacts with the two different versions (5th Gen vs. 6th Gen) of the VFR "Tri-Y" header system. Right off the bat I'm reminded of the 2 choices of header that were available for a motorcycle I have some experience with, the Suzuki GSF400. There was a "four-into-one" header and there was a "Tri-Y" (or call it a 4-into-2-into-one). The "four-into-one" was (supposedly) optimized for high-rpm operation but not so great in the mid-range RPMs, while the "Tri-Y" was (said to be) better in the mid-range RPMs but gave away a bit in the high-rpm.

Wondering: do you always park the bike the same way? is it always on the center stand when parked, or always on the side stand? the thought here is if you park the bike differently sometimes (leaning on the side stand vs. up on the center stand) does that make a difference in whether the engine produces the blue smoke during the next start?

And... Don't be like me... instead of blundering along trying to pull the socket off of the back of the bulb without really knowing/remembering how to release it from the bulb. It's better to refer to the Honda VFR800 Service Manual, page 19-6, for the step-by-step how-to on removing and replacing headlight bulbs on the bike.

you'd be surprised how much better the 5th Gen radiators can dump heat to the atmosphere WHEN THEY'RE CLEAN. many, if not most, 5th Gen owners never think to clean the 20+ years of accumulated road grime off of the radiator cooling fins. a can of spray-on foaming air conditioner coil cleaner will remove the build-up. after cleaning the radiators are able to reject a lot more heat into the airflow around them.

My bet is that all of those Revs are giving the Clutch Slave Cylinder a really good shaking transmitted by way of the clutch pushrod, and that shaking is transmitted up the line (via the incompressible hydraulic fluid) to the Clutch Master Cylinder. So it becomes a "liquid hammer" situation that is strong enough to drive the hydraulic fluid past the rubber sliding seal in the Clutch Master Cylinder. Which allows the clutch to grab as you described.

I've done the full braided stainless steel brake line conversion plus caliper refurbishment plus full system bleed on a 5th Gen VFR800 twice now, once bike with Spiegler lines and one with Galfer lines. And I've also done a full system bleed on a standard (unmodified) VFR800. And for good measure I've always done the bike's hydraulic clutch system at the same time. The best 5th Gen VFR800 linked brake system bleeding results I've had (quickest, less messy, less frustrating) has been when it was done as a 2-person team plus a vacuum bleeder (I use an el-cheapo MityVac purchased at Harbor Freight). The whole process is so much easier when you have somebody to squeeze-and-hold the various master cylinders (the front brake master cylinder lever, the rear brake master cylinder lever, the clutch master cylinder lever, and even having my helper hand-pump the Secondary Master Cylinder which is located on the backside of the bike's front left caliper). But even with the precision/efficiency that this method gives me I've always ended up having to go around all the bleeders twice to get good results. Just last month (May of 2020) I helped another member of this forum who lives here in Denver do a full braided stainless steel line conversion (Galfer lines) and complete refurbishment of the system (all new caliper seals and wiper rings, brake pads, and fluid) on his 2000 5th Gen VFR800. He brought the bike to my home's garage and we did the work over a Saturday and Sunday. I think he would tell you that except for all of the disassembly and reassembly (these two things account for the majority of the effort required) the actual mechanical difficulty just isn't that high.

not necessay. while the brake fluid (hydraulic fluid) is absolutely incompressible, air is very compressible and the volume of it under the reservoir cap is way more than needed in this case.