thefleshrocket

So, it was the battery. I replaced the EarthX LiFePo4 with a known good conventional battery, and have put 400 trouble free miles on the bike since. Thanks to everyone for your input!

Ok, I’ll look at the charging system. I’m 95% sure I put a Rick’s R/R on it a couple thousand miles ago (6 or 7 years ago as the bike sat it pieces in my basement for a long time) and the battery is a several-year-old EarthX LiFePo4 that didn’t have enough CCA to spin my 1125R’s starter but easily cranks the VFR. But I know I haven’t touched the stator. And the fact that charging voltage is sometimes in the mid 14s and other times in the low 13s or upper 12s makes me think one leg of the stator is iffy. So I’ll start by attacking that and leave the MAP sensor alone for the time being. Thanks’

Not sure how to turn on notifications, and I missed the "notify me of replies" button in my original post, but now it's turned on.

My '99 has ~25K miles on it. Last fall, before I put it away, it misfired on me a couple of times shortly after starting up the bike. I looked up the code and it was for the MAP sensor. I bought a used replacement on Ebay (for a 6th gen as it looked "clean" and supposedly it's the same sensor because Honda used it on a bunch of bikes) and installed it. Speaking of which, one screw, one wiring harness, and one vacuum hose.. easy, right? Well, whatever nincompoop decided that the one screw should be on the edge of the airbox facing down with almost no room to get to it without removing the airbox should be punched. It could have easily been secured several other ways with no drawbacks, but no.. took me close to an hour to get the old sensor unscrewed and the new one installed using a right-angle screwdriver. Ugh. Should have just pulled the airbox but didn't want to add any other variables to the equation. Anyway, I fired up the bike and did a 60-mile ride, mostly at high speed (100-125mph cruising speeds.. on an, um, privately owned road), and the bike ran flawlessly. The next day, the battery was dead (I still have to troubleshoot but I suspect one leg of the stator isn't working consistently), but I got it jumpstarted and rode home. The misfire from the past Fall was back. Oddly, it only happened between 4500-6000RPM--if I rode a gear or two low when cruising to keep the RPM up over 6000, or when I was at a slow area and the RPM was under 4K, there were no misfires. But man, get it in the 5-5500 "sweet" spot and it would misfire periodically. When I say misfire, it's like the entire engine cut out for a split second, then came back immediately. Not a miss on one cylinder, but all four of them shutting down very briefly. The FI light would come on for the duration of the misfire and maybe a half second after. I posit that I didn't get any misfires on the initial ride because the RPM was well over 6000 for almost the entire time, aside from initial startup and the first few warmup miles. And I confirmed that there is a stored code for the MAP sensor, so it's not something else that's angry. I realize it's possible that the replacement MAP sensor was also bad, but that seems like a stretch. I could buy another one (and not mount it to the airbox unless the bike runs perfectly) to test it out, but what else should I be looking into if it's not the MAP sensor itself? Thanks!

I put a good 150 miles on my VFR yesterday. This was my first real ride after the bike had been down for several years. And, the shifting felt.. just fine. It wasn't clunky or jerky or missed-shifty or anything like that. (I'm running Amsoil Dominator 15W50, which has made all of my bikes slick-shifting, so maybe that's it.) So I decided to cancel my order for the kit.

Thanks! I just ordered a kit. (I just spent $2500 getting the transmission repaired on my fifth gen, so what's another $225 at this point. LOL)

Aaaand it’s fixed. I had ridden for about 15 miles, and was cruising at about 70mph when the bike surged and started accelerating. I let off the throttle and rolled back on it, and the power was back. Idle is now close to 2000rpm. I think one of the injectors must have been clogged and the bike was running on 3 cylinders. Which makes sense given that it felt like it was down 20-30hp. Whew!

Is there a schraeder valve on the fuel rail, so I can buy a can of the concentrated injector cleaner that you run the bike off of?

You think Seafoam will do the trick, though, or is it gonna need more in-depth work? I gave it a fresh tank of ethanol-free 91, and half a can of Seafoam. Probably won’t get a chance to ride much until next weekend.

Oh okay. Yeah, I'm an avid Seafoam user--have several bottles in the garage right now. I wasn't sure if you meant something like running it through the intake manifold, or if you just meant adding it to the tank. You think it's just running lean right now?

Elaborate, please.

Sliders will NOT give you rash-free fairings in the event of a tipover or low-side. Some part of the fairings will touch the ground. My advice? Skip the sliders altogether, and if you damage a fairing, just have it repaired. I had the R&G sliders on my '99. A 20mph low side resulted in a small amount of rash to the upper and lower fairing. I had the damage repaired and had the body shop fill in the holes where the sliders had gone, and I left them off.

I started taking apart my '99 four or five years ago with the intent of R&Ring the transmission, as it would skip a tooth in second gear. Then I ran out of motivation and the bike sat until recently. The bike was in a climate controlled basement the entire time. I took it to the local Honda shop and paid them to fix the transmission and put the bike back together. I just got it back today. The bike runs and rides perfectly. No hesitation or misfires. Except, it feels like it's way down on power across the powerband. How much, I can't tell, but I'd guess at least 20-30 horsepower. One thing that might be worth mentioning is that I didn't drain the fuel rail or injectors. The Honda tech couldn't get the bike to start and run after the repair, so I told him about how it had most likely had old fuel in the fuel rail. I didn't specifically ask what they did to fix it, but the invoice indicates a fuel injector cleaning, so presumably my suspicion was correct. So far I've only ridden the bike about 10 miles. Is this something that's likely to resolve itself? IE the computer "relearning", or maybe the rings getting worked free and sealing better? If not, what could it be?

Oh yeah, duh. It's been so long since I've ridden this bike that I forgot that one of the things that I love about it is the sound of the gear-driven cams. Since the cams are still driven by the crank, maybe the manual assumes that you're going to be R&Ring the crank if you crack the cases, and therefore the heads need to come off. Eyeballing the exploded diagram on page 8-0 of the manual, it doesn't look like the head bolts are making it into the bottom case.

Oh. Yeah, I see that now part of the manual now. (I'm using the same manual, sourced from here.) I can sorta picture why some of those parts might need to be removed, but others just seem unrelated. For example, why would the heads need to come off? I get it if the crank is being R&Red, since the cam chains are connected to the crank and the heads might need to come off to disconnect the cam chains, but I'm not going to touch the crank.