Thanks. It's not necessarily "user error" but more "incomplete testing" and jumping to conclusions before making a complete analysis.

RTFM! (Read The Fukking Manual) :D


I want to try to get the carbs sorted first and then I'll come back and do a PROPER compression test.

70HP? Might be nice, but I really just want to ride the thing!

RTFM does it for me everytime.lol

Best of luck with it man.. I want to ride it too..and I never built the bloody think from boxes!

Someone help me out here, point me in the right direction. Still not getting anywhere with the "mystery" RVF. I guess the big question is still..............Did this thing ever run right before I got my hands on it? Is there a reason someone got rid of the bike? Was it having problems and that's why it got neglected? Was it dumped at the Japanese auction house only to be shipped to some dumb unsuspecting American? Er, that would be me! Or did it run like a champ and just sat for a long period of time and that's where the problems started? I guess I'll never know for sure. Sure would make it easier knowing because I could say "it ran good until I got my hands on it!" LOL The seller/importer was initially shocked and dumbfounded that I got the bike started on the first day. He said it would need a complete rebuild. He had already written the bike off, maybe he knew more than he was telling me? So I was prepared to do a complete rebuild and that's (sorta) what I've accomplished, sorta.

So, on with the story. After removing and fiddling with the carbs 38 times or so, I started leaning away from them as the root of all evil. So I set about dissecting and examing the ignition system. After all, I checked for spark at all 4 corners about 17 times, so why not check again?! Checked resistance at coils, primary and secondary, checked out normal per Mr. Haynes manual. HT wires, checked. Checked battery and reg/rec output, perfect, within normal spec. Checked the pulsed generator coils, 410 ohms, Haynes says 450-550??? Does anyone think this is significant? Visually checked CDI because that's about all you can do. Checked all electrical connections verifying that yes indeed I had cleaned them all and applied dialectric grease and all was well. Checked and verified that the coil wires were hooked up correctly by looking back at pics of the bike before tear down and markings on wires with Black Sharpie pen, verified with other pics of RVF bikes/coils. Haynes manual electrical diagram appears to show connections in a different manor??? Error???

I'm on my third set of very expensive unobtanium NGK plugs with one more reserve set in the local bank safe deposit box. Took one new plug and went around the motor pulling one plug wire at a time, properly grounding the plug and verifying a nice white hot spark jump the gap at every corner with every revolution. Installed the brand new uber plugs in all four holes. Turn petcock on, key on, switch on run, hit ignition switch with NO CHOKE and it fires up on just a few revolutions on a stone cold motor. Hmmmm, why no choke you ask? Because I'm really paranoid about fouling another set fo these damn plugs! HAHA. Anyway, it starts and settles into an idle, slightly weak idle, but idles none the less. After a few minutes I give it a little rev here and there. It will rev, but it just doesn't sound right, STILL. The exhaust tone is all wrong. I know it every time. It kind of has a crackin', poppin' type mis-fire and then clears out and screams like a banshee. I'm only really going up to 7-8K tops, nothing stratospheric. Instantly I know, it's only running on 3 good cylinders. Initially it was the #2 cylinder, then the #4 cylinder, and the last few weeks it's always the #1 cylinder. Anyway, I let it idle like this until it's up to temp and it will carry on all day. I get some black smoke when revving it up in anger. Not blue smoke, not white smoke, black smoke. Now I notice that turning the idle screw doesn't really change the idle at all. Hmmmmm. I set up the carb butterflies exactly as instructed this time, as per Stickshift. So I pour a little water on the downpipes to check for the cold one because I'm really tired of burning my fingers like a jackass. Lately it's always the #1. All the other ones hiss with steam, and the #1 does nothing. So then I decide to try and open up the pilot screw on that carb #1 while the bike is running and it doesn't change a thing, no chang in the idle tone or revs. This is odd, right, shouldn;t there be some change? Sprayed WD-40 all over the lower carbs and inlet rubber to check for air leaks. Nope, nodda, nothing, zilch. I notice inadvertently that if I switch the petcock to the off position it continues to run on like nothing happened. 5 min, 10 min, etc. Hmmmmmmm, not running out of gas is it. So I pull off the vacuum line off the petcock and plug the vacuum line hole with a nail, and after a few seconds the bike revs up like mad, 5-6-7K rpm. So I reach over and turn the idle screw down, and down, and down, and settles into a normal idle and dies after a minute or so. So that's strange, and I can't seem to explain that one. I've removed, cleaned, and checked the fuel tap only about 7 times, so I should do it again. Nope. I've checked the operation of the fuel tap by applying a vacuum from a Mighty Vac Speed Bleeder and it worked as normal. I get a slight drip from the petcock outlet when the tank is off the bike and the petcock is in the off position, sitting on the table, but only a few drops. It's not leaking anywhere else, yup, I've checked. The carbs are gravity fed from the tank, correct? It doesn;t rely on vacuum pressure from the carbs at all, right? Anyway, when pulling the #1 spark plug it's just a little brown and that's it. It's not drenched in fuel or fouled in any way. The other plugs don;t look too bad either. At least I'm not fouling the damn things. I still haven't done the complete compression test and at this point I really don't care. It's not blowing oil smoke and the 3 good cylinders are running fine. I am convinced if I could get that last cylinder than I might be OK to start with as a baseline and then I'll re-borrow the digital carb tuner. Just don;t know where else to look at this point. Getting rather frustrated. I'm going to take few days to "step away". I was sick as a dog (nasty flu) all week and actually missed 3 days of work for the first time in 18 years so I'm mentally and physically not in a good way at this point.

In conclusion. HELP?!

Bit of a case you've got there!

I would rule out engine and electrical problems, on these bikes they either work or they don't.

Certainly a fuelling issue in my opinion. Are you running the recommended pilot screw settings? The setting you had were very rich and the plugs would be prone to fouling.

Are you certain that the plugs aren't being fouled? When I've had nc's only running on 3 cylinders this is always the case, finding out why is the tricky bit but it can only be related to the amount of fuel put in by the carbs.

I would bet that plugs are being fouled by your carb settings at some stage, the small suckers are fragile and can't always be resuscitated! When fouled they play up more easily, if treated well they last more than 25,000 km's (tried and proven!).

Yes the carbs are gravity fed but you need a vacuum to open the fuel tap. Disconnected the vacuum while it's running will lean the engine out and it will rev up before dying. If you want to rule out the tap just run it from a makeshift petrol drum for a tank, etc.

Good luck!

I would rule out engine and electrical problems, on these bikes they either work or they don't.

In my experience, when the HT side of the ignition system begins to break down due to age, there's a gradual degradation in performance and/or intermittent faults that can be very difficult to diagnose without spares to hand.

It's odd that the poorly cylinder seems to move around, and I would observe from your tale of woe so far that you're attempting to make multiple adjustments at once. Take heart from this; if you had lost compression on a cylinder it would always be the same pipe that's cold!
I wonder if your attempts at fixing the problem is in itself introducing this seemingly random element?

Why not leave the carbs alone for a bit and concentrate on establishing the health of the ignition circuit. If you can do that, and you've done a second compression test and all is well, then it's likely to be a fault in the fuel system that you haven't diagnosed yet. Of course, if the compression test confirms your first results you'll need to check the valves / pistons.

You've visually checked there's a healthy spark at each plug, but this isn't the same as subjecting the ignition system to sustained pulses; are you able to swap the coils / HT leads around to eliminate them being at fault?

At the end of the day, bikes / cars / whatever are simple in nature, you just need a methodical approach and to take your time.

Chin up, and persevere. It'll be worth all the effort in the end when you take her out for the first time!

Wasn't the carbs or fueling changes!

So, took a break from the bike to clear my head over the last few weeks and was busy with work. When, I brought the bike home initially I took hundreds of digital pics of everything and labeled every nut, bolt, and wire with a black Sharpie pen. I did this so I would have a reference if I forgot how things went, or more specifically how they were WHEN I GOT THE BIKE. Now this doesn't help if things were wrong WHEN I GOT THE BIKE. A few months ago I looked at the possibility of maybe I accidently swapped the connections on the coils. Nope, checked with the digital pics and labels and everything was the same. I even checked a few pics of other RVF's just to be sure, and it APPEARED from a distance their connections were the same. Well, fuck me if it turns out that the coil connections were all ass backwards from the beginning. Somebody in Japan, before this bike was shipped to the US, either swapped coils, swapped CDI's, swapped HT leads, or switched all the connections for some dumb reason. No wonder they dumped the bike with 8000KM on the clocks. I am sure it never ran right and they got tired of messing with it. The Haynes manual has a luverly set of color wiring diagrams, one for the VFR and one for the RVF. Well it turns out the coil connections are exact opposite, and my RVF was wired like a VFR and not like a RVF.


VFR400 NC-30
#1 - black with white wire
#2 - black with white wire
#3 - yellow with blue wire
#4 - blue with yellow wire

RVF400 NC-35
#1 - yellow with blue wire
#2 - blue with yellow wire
#3 - black with white wire
#4 - black with white wire


It appears the wiring coming off the CDI is in the same order on the VFR as on the RVF (from lateral to medial on the unit), blue with yellow, yellow with blue, and black with white. So maybe someone in Japan was screwing around with something and hooked the wires up like a VFR? I don't know. Swapped the HT leads, coils, whatever? For what reason, I dunno? In any event, apparently, a 400cc Honda V-4 can actually run with the firing order inadvertently screwed up, running off mainly 3 cylinders at any one given moment. And apparently this can mess with the combustion of the motor, foul expensive little spark plugs, and make it do all kinds of silly things causing much loss of sleep in the frustrated owner!

In conclusion, it's amazing how well these bikes run when they are firing on all 4 cyclinders in the proper firing order. Doh!

Good result!

At least you've got to know the bike intimately!


If the rvf is anything like the vfr the coil terminals are colour coded to the wires.

I just went and had a look in the garage and they are not hooked up in color coded fashion. The black/white wires are on the blue coil terminal and the blue/yellow wires are on the black coil terminal, front and back. ????????? Do you think maybe I have VFR coils on the bike and that's why someone hooked them up backwards? Is there a difference? Would that make a difference? It doesn't seem like it would. I suppose I could reverse the coil wires and reverse the HT leads wires and then they would be hooked up based on color. I guess it really doesn't matter as long as it's running right? Cheers! Great WSBK racing down under this weekend, eh?!

Oh, one more thing, what are the markings and numbers on your coils, ie. manufacturer, part number? Or anyone else for that matter. I'm interested in seeing if mine are the same or different. Wondering if they are even the standard/proper coils or not?

I am thinking someone in Japan is having a laugh at this very moment. "Ha, Ha, we ah got him guud!"

RVFHooligan wrote: I suppose I could reverse the coil wires and reverse the HT leads wires and then they would be hooked up based on color.

Just a thought, maybe the leads are on the wrong coil caps?

I don't know if it matters because the nc's fire the fronts together and the rears together?

Great news Jeff, you win!

I have several sets of coils and will check the markings on them and report back.