RC51 Electrical Problem

[adamgh81]

Ok, my 2003 RC51 has ran flawlessly until a few months ago.

4 Months ago: Battery started dying. No Problem, New Battery

3 Months ago: New Battery dies. No Problem, replace regulator/rectifier and charge battery.

Now: Bike won't start. New battery was replaced with even a newer fully charged Yuasa battery (stupid asian batteries, Yuasa all the way!)

When I crank the bike, it sounds weak (Keep in mind, brand new battery) and won't turn over. Checked all the obvious things: Air filter, I smell fuel out the exhaust, the engine turns, so it's not hydrolocked in anyway. It's not the BAS or the kickstand or clutch switch because the engine wouldn't crank if those were an issue. Plus it doesn't fit the battery draining mystery.

Here's my theory: Somewhere in the wiring harness between the battery and the starter, there is a weak connection and current isn't flowing properly to complete the electrical circuit from the battery to the stator to the R/R and back to the battery.

Everyone else agree? Any other ideas?

I've checked the grounding points and they all seem solid. I've heard other RC51's have similar problems with electrical harnesses, but I can't fine the problem area. Honda NW blew me off when I called and said they can't get me in until March to look at it. It's probably something so simple that I'm going to go nuts when it does start.

I'm in Pickingington if anyone is interested in stopping by and taking a look at it. Beer can be provided. I'm sick of my pig sitting in pieces in my garage as this weather warms up. I have a random work schedule, but let me know if anyone is interested in helping a brother out. Thanks in advance!

[RC51 John]

I haven't had any charging issues., but I found this on SpeedZilla.com

Starting Problem...regulator rectifier or stator?

Oops. that was posted by you.

[Disclaimer]

I think you've already figured out your problem. Check the charging system. You could have a broken leg from the stator to the regulator rectifier (only running on 2 legs out of 3).

Kind of similar to the problem I had with my old bike.

If that's not the case, you might have to tear into the stator and check electrical specs on it - it may be your next replaced part.

[12oclocker]

I think you've already figured out your problem. Check the charging system. You could have a broken leg from the stator to the regulator rectifier (only running on 2 legs out of 3).

Kind of similar to the problem I had with my old bike.

If that's not the case, you might have to tear into the stator and check electrical specs on it - it may be your next replaced part.

+1 good recommendation.

...get you a multimeter out and start probing.

[RC51 John]

+1 good recommendation.

...get you a multimeter out and start probing.

That's what she said.

[adamgh81]

Oops. that was posted by you.

Yes, fucking hilarious, I've been nursing this problem for months and keep getting pissed, put her in the corner and forget about her for a few more weeks. I've got a multimeter but I don't know a whole lot about electrical issues.

[ReconRat]

The absolute first thing I always check, is the ground side of the battery where it is bolted to the chassis. If it's a bad connection, everything goes south and don't come back. I check it by removing and cleaning the connection. This connection often corrodes, and usually nothing looks wrong. You can use the multimeter to check it, disconnect battery, and check resistance between negative battery lead and the chassis anywhere. It should read nearly zero resistance.

A bad alternator output, like one with a broken coil set wire, will work fine right after you charge the battery, and run the battery down till you charge it again. At least that's what mine did.

It definitely needs traced with that multimeter. Either there's a short or an open resistance drawing current away. Sometimes checking for a short at the fuse box with the multimeter is quicker. Although things that run with the key off, like clocks and alarms, will give a false reading. You really need a schematic or wiring diagram to do this.

Shorts are going to be found by unplugging stuff till the problem goes away. If it's as bad as you say, probably don't even need the multimeter to do that. The multimeter would only say you have a short, go find it. Sometimes popping fuses out will isolate which circuit is the problem.

I found one like this at the fuse box. The main fuse holder was copper, and brown from age. It was hot, too much resistance. Cleaned it and was good to go.

And oddly enough, the key switch itself is a notorious place for a short to occur. Usually discovered by jiggling the key and having things flicker or act up.

And then there is the other stuff. The engine doesn't want to start, but how is everything else? Headlight work? Horn work? Horn weak when brake light is on? Headlights nearly go out when trying to start? (more than normal anyway). It might be possible to narrow it down to the ignition circuit connections and parts, if everything else acts ok.

[ReconRat]

And yeah, check the new battery with the multimeter to see if it's got 13.8 to 14.5 VDC. It might need a first charge to work.

[Mister2]

also do a voltage drop test from battery then at starter, will tell u if u have an open anywhere in that circuit.

[adamgh81]

Thanks for the info rat.

Mister, how do I do a voltage drop test?

[ReconRat]

http://en.allexperts.com/q/Motorcycle-Repair-837/1983-Honda-V45-Magna-2.htm

A good example of a voltage drop test on a Magna V45 on this webpage.

[The King]

You say it is weak but you also say it won't turn over....

Have you checked the starter itself?

[adamgh81]

You say it is weak but you also say it won't turn over....

Sorry, I meant to say it is weak when turning over but won't kick over like a normal start. It doesn't even try to start, just turns and turns.

[The King]

I wonder if you fouled the plugs..

[KruelHouse]

I had a similar problem last year. If you have a power commander, check the cable going to the neg. terminal. A loose connection, or wire damage (as was my case), will yield the aforementioned results.

Other than that, check your fuel pump. When you turn on the bike, if it sounds weak when it "primes" (and you batt. is strong/new as you stated), it could be on its way out.

Along with the fuel pump, your fuel filter could also be heavily clogged... If it is a pump/filter prob. let me know as I have an extra fuel pump that we could work with.

Good luck!

[adamgh81]

I wonder if you fouled the plugs..

Plugs are in good condition, good spark also.

[adamgh81]

Kruel - I do have a power commander, I'll double check the connections, they looked good before. The fuel pump primes fine with the new battery. I have not checked the fuel filter, but I do smell fuel in the right exhaust pipe after trying to start her.

[The King]

I bet money it's the PC.

[RC51 John]

Yes, fucking hilarious, I've been nursing this problem for months and keep getting pissed, put her in the corner and forget about her for a few more weeks. I've got a multimeter but I don't know a whole lot about electrical issues.

H3ere is an electrical schematic for the 2000 model.

I'm not sure if it's the same as the 2003.

[RC51 John]

Wow, is that big enough?

[adamgh81]

thanks john, i don't know much about electrical shit so i don't even know where to start with the diagram. if your interested in troubleshooting it with me, let me know.

[phugitive]

A simple way to check your starter ground:

You will need a wire and 2 aligator clips.

Hook up one end of the wire with an aligator clip to the negitive side of your battery leaving the battery connect as it normally is.

Hook the other end of your ground wire to the starter body with an aligator clip.

If starter speeds up you have a grounding issue.

[phugitive]

Your starter may be bad:

If you have good connections to the starter.

A good fully charged battery.

No major engine trouble.

Starter still turns engine over slowly.

A shorted out starter will not only run a battery dead but can ruin a battery.

Also since the starter is taking all the power, the engine may not start even though it is turning over.

Three ways to check a starter:

If your headlight goes out or dim while trying to start it, it may be bad.

Take starter out, use a manual and multi meter to check it.

Take starter out and have it checked at the dealer, call them first.

Good Luck

[adamgh81]

If anyone is willing to take a look at my bike before I drop it off at a shop, please let me know. I'll give you some cash if you make any progress. I need to get this thing started now!

[jbot]

Ok, my 2003 RC51 has ran flawlessly until a few months ago.

4 Months ago: Battery started dying. No Problem, New Battery

3 Months ago: New Battery dies. No Problem, replace regulator/rectifier and charge battery.

Now: Bike won't start. New battery was replaced with even a newer fully charged Yuasa battery (stupid asian batteries, Yuasa all the way!)

When I crank the bike, it sounds weak (Keep in mind, brand new battery) and won't turn over. Checked all the obvious things: Air filter, I smell fuel out the exhaust, the engine turns, so it's not hydrolocked in anyway. It's not the BAS or the kickstand or clutch switch because the engine wouldn't crank if those were an issue. Plus it doesn't fit the battery draining mystery.

Here's my theory: Somewhere in the wiring harness between the battery and the starter, there is a weak connection and current isn't flowing properly to complete the electrical circuit from the battery to the stator to the R/R and back to the battery.

Everyone else agree? Any other ideas?

I've checked the grounding points and they all seem solid. I've heard other RC51's have similar problems with electrical harnesses, but I can't fine the problem area. Honda NW blew me off when I called and said they can't get me in until March to look at it. It's probably something so simple that I'm going to go nuts when it does start.

I'm in Pickingington if anyone is interested in stopping by and taking a look at it. Beer can be provided. I'm sick of my pig sitting in pieces in my garage as this weather warms up. I have a random work schedule, but let me know if anyone is interested in helping a brother out. Thanks in advance!

lol wut

where do you think yuasa batteries come from?

have you looked on rc51 forums? (try speedzilla and fireblades.org) i'm sure it is a common problem. from what i've read up on other bikes, it may be the stator? or maybe the relay connector (if there is such a thing on the fitty one cent)

hope you get it worked out.