Baby Viff - 1986 Honda VFR 400

[Daschicken]

Originally Posted by Grant-53

I sold thousands of thermostats for cars, all had the spring firmly attached.

The spring I put in there is not related to the thermostat opening, it was just to put pressure on it so it wasn't loose. That was to see if water was leaking around the thermostat, and it was.

[Daschicken]

Got the new thermostat, but its got the same damn problem as the old one. It rattles in the housing and probably wont seal up to water, acting as if it was stuck open.



The new thermostat indicates an opening temperature of 82 Celsius, or 180 failheit. The previous one appeared to open(reverse tested by putting in hot water and seeing when it closed) at 172F, so if I get this working it should be even better for gas mileage than the OEM thermostat.

[Grant-53]

Most auto parts stores sell thermostats that open at 185 F last I checked. The size from the picture seems close to the same diameter as a car or light truck unit.

[Daschicken]

I took the NC30 apart to see how its working thermostat situation looked like. It turns out the NC30 housing also lets the thermostat rattle around.



Both thermostats are 82C rated.

So when I first took mine apart and tested it, I remembered it flowing a lot more water than the bypass hole should allow. I redid the flow test comparing both the NC21 and NC30 thermostat housing, with the new and old thermostat for the NC21. They all flowed a small stream. It is possible at some point there was a chunk of rust that lodged itself between the thermostat and the housing allowing water to bypass it. Anyways, its gone now!

Baby viff is put back together now. Just have to wait to take it for a ride and see if it heats up. If not, its time to start blocking the radiator.

[Daschicken]

Me and dad went out for a ride today, my vfr 400 still did not heat up. The gauge will be 1/4 - 1/3 of the way up. So I started blocking the radiator with some clear tape in sections. The first few strips of tape helped, but it wasn't enough. I added another strip and it helped more, but I feel like it could use at least one more strip. With the current amount of blockage, the gauge reads probably 45% of the way up, unless I am going downhill. I have established the deadzone's RPM range, it is between 5000-8000. Right smack dab in what would be useful midrange.

My first fillup of the trip included bleeding the cooling system(idling) and lots of NASCAR mode. 48.3 MPG.

The second fillup was where I started blocking the radiator, and I did a good bit of 65-70 mph highway travel while doing some serious tucking. Much less NASCAR mode, but I still 'floored' it a few times. Finally broke the 50 MPG barrier, and beat my dad's mileage too! 52.7 MPG.

I also weighed both VFR 400s using the method detailed in my CBR 250R thread. Both were a pleasant surprise. My NC21 weighs 410 pounds with the stock muffler, but missing a chain guard and the "ram air intake" pipes. The NC30 weighs 411 pounds with a lighter aftermarket muffler, and tires that are more worn than mine. People on forums were seeming to suggest that the NC30 was significantly lighter than the nc24/nc21, that is not the case. At least for the NC21 it isn't. Looks like the NC30 would be a good 10 pounds heavier all things equal.

Edit: Published curb weight for the NC30 is 423 pounds. I was pretty close. Curb weight for the NC24 is 425 pounds.

[Daschicken]

A bit ago my VFR 400 decided to blow out its rear shock and leak its shock oil all over the place. Unfortunately, these shocks are non rebuildable. The bike is from 1986, so any used units are already questionable just from age alone. New parts are non-existant. One company makes a shock that will fit the bike, the UK division of Hagon.

So, more than $400 later:



The thing is an absolute beauty, and as you will see later on it is actually smaller(and lighter!) than the original shock. There is no remote preload adjuster like in the original, but I don't see myself adjusting the preload to begin with, let alone adjusting it frequently enough to justify a remote adjuster.


Getting the original shock out SHOULD have been not so bad, but it turned out to be a PITA. To take the shock out, you have to unbolt the dogbone and get it out of the way. Well it just so turned out the one bolt holding the dogbone in place had rusted/pitted itself into place and didn't want to come out! The thing would spin, but it wouldn't come out. Lots of PB blaster and some pounding a day later eventually freed up the bolt.



Here is a side by side comparison of the shock that came out vs the new shiny one going in. The old one weighs 6.5 pounds, the new one is 4.65 pounds. Since the new shock is also smaller in diameter, installation was easier too! The rear feels squishier now from what I remember, probably better suited to my weight. Other than that, it feels pretty normal. My test route didn't have any speedbumps or other bumps to test suspension over.

[Daschicken]

The VFR 400’s tach used to go crazy above 9000 RPM, then that dropped down to 5000, then 3000. Any more throttle than needed for cruising would cause the tach to act funky. Tonight I finally fixed it!



There were three related connections behind the front fairing, two were visibly corroded. Cleaned all of them up with sandpaper and some contact cleaner. Finished up with dielectric grease and put it back together. After having the tach not work and taking it apart again I discovered that third contact was unplugged.

A short test ride up to 5000 RPM shows no weird tach problems. I’ll have to take it all the way to 13,000 and see if I can find the rev limiter again. It either disappeared when the tach was acting up, or I was hesitant to keep revving an engine without a tachometer.

Still have to fix the mid range flat spot, will probably get it dynoed with a A/F readout to see what’s wrong.

Me and my dad are taking both the VFR 400s out to go look at.......ANOTHER VFR 400. Even if we don’t end up getting it, we will have a cool picture of all three generations of the VFR 400(not including RVF).

Edit: It was in pieces, no picture.. Tach works fine, rev limiter is there, seems to kick in around 14,000 rpm.

[Daschicken]

Well, we did it again....



We got ourselves another VFR 400, this time an NC24. So we now have all 3 generations of the VFR 400, excluding the RVF 400.

It had been brought into the country by its British previous owner, who was getting too old, and lost interest in it. It did come with original fairings and tank, but they are painted a dark red color. Bike was apart in the picture because me and dad were working on it. Tank has some overspray inside, but otherwise looks fine. One of the carbs was clogged up and the slides are slow to return, so it may need some parts. I was eager to see if it would run again for the first time in 5+ years, so the carbs, tank, and battery were swapped over. It cranked over fine, but wasn't getting spark. Checked the killswitch...seems fine. Then my dad finds an unplugged connector where the seat would be. It fired right up after that!

It will need some parts and other crap, including tires, before it is ready to actually ride, but I did take it for a short test ride and verified that all six gears worked! The tachometer does appear to be reading double however.

The single sided swingarm definitely earns cool points, and hopefully mid range power will be improved over my NC21 due to the NC24's sizable velocity stacks. Just have to get the carbs working!

[Daschicken]

Originally Posted by rajputrana

The Honda VFR400 sequence of motorcycles were a allied sequence of 399 cc V4-engined motorcycles, which were effectively scaled-down versions of the bigger VFR take part models of the day.

Yeah.....????

They are certainly scaled down in size and power, but not in fun! I haven't ridden a period correct VFR 750, but I have ridden the successor to it, the fuel injected VFR 800. Fuel injection makes it easier to live with, and gives it dramatically improved throttle response over the 400s, but the gearing is just too tall to have fun at low speeds. The fuel economy of the 800 isn't anything to write home about either, but then again my 400 is the same way.

[jimhs]

Which vfr800?
If you have any experience on this bike play write a sort review.