Electrical Issues

[Neosophist]

Off topic but the brake fluid looks a bit dark too and i'd replace the original rubber hoses... Honda recommends changing after 6 years.

They will be nigh on 20+ years old.

[RegionX]

Thanks, I will be doing a full service, changing all fluids, clean and rejet carbs, valve clearances, obviously a lot of rewiring, spraying the bike and I guess replacing the break lines too. I think its the plastic that is dirty and the angle that makes it look bad but it's a good idea either way.

1.) I would really like to test the dash, with my old bike if I earthed the thermostat wire the temp gauge would shoot up indicating that it was still functional, surely there is a similar test?

2.) I charge the battery fully, the bike struggles to start but eventually fires after about 4 or 5 attempts. It then runs really well, sounds good a bit of white smoke which I assume is from all the petrol being sucked in while its not starting. I run it for about 5 min but when I come to start it again it just wont fire. Would I be right in saying that I am running the battery flat when trying to start it and then 5 min is not long enough to charge it up again for the next time and the fact that it struggles to start is a sign of a bad battery anyway? The voltage when fully charged seems fine at about 12.85 but after cranking with no luck (For looong) it can drop to 12.2V. While cranking battery sits at about 11V when fully charged.

[CRM]

looks like gullarm or early blade clockset.
remove and replace with correct items.

This bike is far from standard and there is a good chance the tacho works so why would I spend the money?

ah sorry i thought you just wanted it to work without hassle.
may have something to do with the IL4's and V4's being different firing pattern and not sending the signal from the CDI the same.
NC30 cdi being happy talking to a NC30 tacho and all, besides you can pick up clocks for bugger all, i appreciate it may be a bit of a frankenstein bike but it wont cost much to put the clocks right will it ?
anyway your bike - your budget

[RegionX]

Ok well I'l try get it to work and speak to the previous as I cant seem to find any for sale at the moment in S.A. Still wondering about if the problem is with the battery or carbs/wiring/engine, what would make the bike struggle to start but run great when it finally starts besides the battery?

[magg]

Is S.A. south oz? 12.2 volts while cranking a non start engine is good for a battery of unknown history but then you mention a battery voltage of 11 volts that appears to contradict your earlier comment, could you clarify please. 5 minutes runnig time is long enough to get some charge into the batter. What voltage do you measure across the battery when the engine is running, should be 13-14 volts. If not you need to start checking the charging system.

Regarding the tacho, actually you say it does not work so although getting an OEM unit with the correct wire colour code might cost more, it should work first up. ebay or grey imports in oz is a good place to start for OEM tacho or if you want to try with the one you have, maybe it expects a drive signal from the ignition coil not the CDI. Which wire is the drive signal is the problem, is the tacho currently wired into the loom and if so which wires go to which in the loom.

[Cammo]

I don't know of any other Honda tachos that will work on nc30's.

Replacing yours with a standard one will save the ballache.

[RegionX]

Firstly my apologies for not being very clear. I thought my location was displayed, I'm in South Africa.

The voltage when fully charged seems fine at about 12.85 but after cranking with no luck (For looong) it can drop to 12.2V. While cranking battery sits at about 11V when fully charged.

12.2 was not during but after cranking, during was 11V. With regards to the tacho the owner says it was working at some point, it is not just the colour code that is off, I havn't seen any wires in the loom that match the colour wiring diagram except maybe the green which I think is the negative? This is the reason I havn'r been able to attempt rewiring.

After charging the battery last night it actually went to 13.2V, I then tried to start and it struggled again but it seems that as I let go of the button it tries to fire. So the next time as I let go (of the button) I bliped the throttle and it started, no choke (because I always think its flooded). I ran it for close to 10min and after the charge had gone up to 13.3V so it is charging.

Will find out soon if it struggles to start from cold again but the way it tries to fire as I let go of the start button indicates electrical problem, right?

[RegionX]

I can do ebay if I have to but they are going at 45 pounds before postage, that is 5% of what I payed for the bike and so far the smallest problem I have. I am trying to sort it out as cost effectively as possible but will spend the money on the important stuff and at this point I'm not sure it is that important as I still have hope its been wired up to work in the past. I will try find one locally first but they are few and far between.

I want to ask about cam noise but maybe it should wait till this is cleared up.

[RegionX]

Sorry if I'm overposting but I feel I should clarify further...

I am an Electro-Mechanical Engineering student and buy bikes to fix, learn, ride and in the end make some money. I have successfully done 2 2-strokes and have now stepped up my game . No work will ever be a ball-ache but spending un-accounted for cash is a knock to the groin area. I am only at the end of my 2nd year of Uni and therefore havn't gotten too far in to the electrical side of things, its mostly been Maths and Physics but I have done some basic concepts of electrical engineering.

Just thought it would be easier to offer advise knowing that I am not the typical bike owner. I plan on sticking with these bikes for a while and when I have enough cash, keeping an RVF for myself.

[Neosophist]

I havn't looked at the wiring for the VFR rev counter but it shouldn't be any different from any other tacho.

You should 3 wires to make the tacho work.

+ve / -ve and what i'll call 'sense'

The +ve and -ve are self explanatory... check you have 12v when the ignition is turned on and that part is good. (If you find out what the clocks are originally off you can get hold of the wiring diagram for that bike off the net so you know which 3 wires are which, otherwise you can disassemble the tacho and see where the wires goto, +ve and -ve will be fairly easy to suss out and your remainder will be the sense)

The sense wire receives pulses from either the iginition box or on some configurations the coil itself (usually the negative side).

I believe the VFR's run their tacho from the Ignition box directly, so you need to get hold of the VFR wiring diagram and follow the rev-counter feed wire from the ignition box and make sure it's connected to your tacho's 'sense' wire. (and obviously that you have good power and earth)

The final problem after verifying it's wired up if it still isn't working is the actual RPM pulse, the Tacho is expecting a given pulse for given rpm, depending on the bike it originated from and the bike being put on they might not be comptaible, in this case you'll either get inaccurate revs or nothing at all. (from memory you can't just swap the NC30 to NC35 tacho without the ignition box and pick up coils too as the pulse is different?)

Since you don't know if the rev counter was working to begin with you can only connect it up and see what you get. If nothing then the best option would be to replace with an NC30 counter, you know this will work.

http://www.ebay.co.uk/itm/HONDA-VFR400- ... 2c6041bfbb

The tacho unit should come out seperatly (most Honda stuff is plug and play) and fit somethign like the above.

PS: You don't need a degree in mechanical engineering to be good with a bikes electrical system, just lots of work and a good understanding. Most, if not all of the most skillful bicycle mechanics I know don't have any form of education in that specific field, just knowledge from years of messing.

When people are saying just replace it with the proper one, I dont' think they are underestimating your ability, it's just usually the easiest option.

See how you get on anyway and let us know if it works.