electrical issues and headlight on '86 FJ 1200

[mvladutoiu]

Hi guys,
I have a couple problems I need help with, and I couldn't find other threads really addressing the issues (if there are other threads addressing these exact issues, please just share a link):
1.   the bike starts quick and smooth when engine is cold, but after running through the city and engine is hot, the battery behaves as if almost dead (hardly turns the engine over). After engine cools off, it starts great again. What could possibly determine that? (I had a '78 Honda CB that used to behave in exact same way, so I thought it's just old bikes being old bikes, but I thought I'd better ask)
2.   The bike died suddenly on me a couple of times (while running on the street), and so I started taking things apart, since I am almost 100% it is electrical (sudden death, no choking up, no warning). From everything that I read, I figured I best take apart all the electrical points of contact and clean them up. As I did that, I got to the headlight, I really took it apart, and I found that my lightbulb had been rusted on the end, and the plastic thingie with 3 prongs going into it had one of the prongs almost melted off. I'm guessing a faulty contact, then overheating. First question: could a faulty contact in the headlight really kill all the electrical to the point of stopping the engine? Second question: as I took the headlight apart, I noticed that the reflecting part inside the headlight has one of the two supports broken off, so it is wiggling inside (which probably helped the faulty contact). I could go in and fix that, but only if I take off the front glass. There are 3 metal clamps I took off, but it seems glued on. Is it really glued, or is it stuck there just because of all the years it hasn't been taken apart? and how could I take it off (I read about the oven method in some places, but wanted to sound that off of you). Any thoughts?
Thanks a lot. Sorry for the long story, but I figured better more details up front, rather than frustrating everyone with not enough.

[FJmonkey]

Hot starts, sounds like my '86. I crack the throttle open about an 1/8 during hot starts and it helps. Replacing your old 2 brush starter for a 4 brush starter is a better long term fix.

A melted headlamp connector suggests high resistance, poor connection. Clean the connectors well. You can get a ceramic connector to replace it. Search for the headlamp relay mod, it connects the headlamp directly to the battery and bypasses the OEM harness. 

[ribbert]

Hi guys,
I have a couple problems I need help with.....

1.   the bike starts quick and smooth when engine is cold, but after running through the city and engine is hot, the battery behaves as if almost dead (hardly turns the engine over). After engine cools off,       it starts great again.
2.   ....... I could go in and fix that, but only if I take off the front glass. There are 3 metal clamps I took off, but it seems glued on.

1. It's the starter, not the battery and it's a common issue. Even a 4 brush starter will behave this way when it's tired.

2. I briefly attempted this years ago for the purpose of polishing the reflector (talk about extra light for free!) Experience told me it was a job guaranteed to end in tears and I did not have a spare lens so I left it.
If it was me I would exhaust other possible means of repair first (I have, for example, pop rivetted sockets from behind) look around for a complete replacement or if it absolutely had to be split, make sure you get some sort of consensus from internet "experts" on a successful method.

I'm sure it can be done but with the glass as rare as it is, it would be my last option.

The usual fix for a semi sealed beam is just to replace it, assuming of course they are available or universal, as in cars, but for our old machines, no such luck.

Noel

[markmartin]

This company makes a good headlight wiring harness that will fit our FJ's and provide nice fat wires  to your headlight, leaving the skinny wires to run a relay switch.  http://www.easternbeaver.com/Main/Wiring_Kits/H4_Kits/h4_kits.html


I would be helpful if you put a multi-meter on your battery and recorded the readings when it not running, running at idle, running at 3000 - 4000 RPMs, and also see how much the voltage drops off when you change from high beam to low beam.  It's a long shot but maybe something is draining your battery or perhaps overcharging your battery. 

[mvladutoiu]

Thanks guys... I will follow your advice... I'm taking and tracing back all the wires, one by one, and check and clean out all the contacts everywhere. Hopefully I'll find a replacement for the melted headlamp connector from the shop selling the lightbulbs. As for the front face of the headlight, I kind of thought it would be dangerous to mess it up, but if I come up with some brilliant, never-thought-of before idea, I'll post it (although I am a house framer by trade more than a mechanic, the wheel grinder or the skil saw might not work on this one  ) if you really think it's just a tired starter, I looked ebay up and they don't seem to be expensive.

[markmartin]

I just saw Noels response concerning the starter.  I saw this after I had posted, so I'm not attempting to overrule Noel.  No ill intent, nor do I claim to have better information or experience -- on the contrary. However,  I've experienced this same problem -- no turning over on a hot engine and am trying to figure it out.

I changed my starter to a 4 brush starter a few years back, (granted an e-bay China knock-off) and still experienced the same problem.  I installed a large lithium ion battery and new regulator and have not experienced this problem since, however, I did run into a discharging problem due to a bad generator wire connector.  The discharging problem appears to have been remedied.

My logic/theory/guess is that these -no hot start- problems may stem from an over-charging of the battery from a bad regulator, or a slow discharge from a bad wire connector or some other source. The bike starts fine after it has cooled down because the battery has had time to recover.

That's my theory.  Am I going down the wrong path?

Has anyone with a new voltage regulator and a decent battery experienced the 'no hot start' ??

[mvladutoiu]

Ya'll be pleased to know that I finally put it all back together. I doublechecked all the electrical harness, changed the connector to the headlamp. Got a contact spray and took apart all the possible connections on all the modules that I could find and cleaned them up nice. I couldn't get my hands on the place where the ground actually connects to the engine block (too many things to take apart to get there), but it looked fine, and I did spray it generously.
I checked the bike, seems to have no electricity leaking through the bike's body (no ohm reading on the body). Checked the voltage, it shows 12.15 with engine stopped, about 12.05 with engine started (at 1100 rpm) and about 14.4-14.5 at about 3500-4000 rpm. From what I've been reading, it seems ok to me.
I didn't take the headlamp apart, but I did manage to get in with special glue and fix the broken supporting leg inside the headlamp (which was making the light bulb bounce around inside, hence probably also the burned out lightbulb connector - that and just plain old age.

Started it up, 40 km later it still runs fine, but still experiencing the no hot starts. I will have to check into either voltage regulator or 4-brush starter, as you all suggested. Maybe I'll try both, if they are not too expensive, by the time I get them delivered.

Thanks for all the help.