Here is a video explaining this procedure. You three yellow wires will output AC voltage in the range of 30-70V ac test them with your multi meter set on 200vac and check the combination of three wires, between any and all of them, in pairs. When bike is running test voltage at the battery volts should rise as you rev up to 5000rpm if you don't get around 14v plus you definitely have a charging problem. Gauge is Bright High Quality Chrome plated and clamps onto 7/8" Bars and can be easily wired into any point in the system (before a switched load is best). If your battery is charging perfectly but your motorcycle still seems to keep killing the battery. Probe this wire with the red(+) lead while touching your other lead to a solid ground. Some ignitions may have multiple positions,. 13.5 amps and are prone to be even lower with old wires and poor connections. So i still don't know if the lack of green, ground, in my wires plug going to the rectifier / regulator unit, would prevent the alternator from delivering voltage. Set your multimeter to the resistance (ohms ) setting. I believe that bike is one of the early line of DOHC fours. The Fora platform includes forum software by XenForo. im gonna hook the ac gen up to an oscilliscope and see wtf's goin on. *Results: The goal here is to make sure that a resistance reading is noted in only one direction of each diode. [] the key on giving you battery voltage? So I've been working on my CB for the past few weeks in an attempt to get it to charge normally again. I had a similar problem with my 750. Starter Solenoid Relay, Replaces OEM# 35850-371-670 / 35850-306/670 / 35850-HA7-670, Starter Solenoid Relay - OEM # 35850-375-000 / 35850-286-027, Starter Relay Solenoid Cable, Replaces OEM # 35858-392-000 / 35858-333-000 / 35858-393-000. Im pulling my hair out. They can also be found in the center of the alternating system like on the older CB750s (30 pages) Motorcycle Honda CB750 Shop Manual. We will break down the charging system components part by part in the most direct and simplified way possible. OK, the yellows are not grounded out which I assume is good. The specific value of this number differentiates from bike to bike. Anyway the DOHC CB 750s are known for really bad electrics. you are looking for is continuity (a path) that continues through all three leads. These readings should be closely in range of each other. It fluctuates 12-12.5V v depending on the battery charge and the rpm. 3. JavaScript is disabled. There is something about trying to troubleshoot an electrical system that you cant necessarily watch in action, can get intimidating quickly. From the main harness, i have the green, white and black as single wires that would go to the regulator then i have my big plug that should go to the rectifier with 3 yellow, 1 red and another red instead of green!! TESTED ALTERNATOR SEEMS TO BE WORKING Answered in 12 minutes by: In which case the stator has begun to break down or is bad. Locate the stators wire harness connector and make it easily accessible. Since the rectifier is made up of multiple one way valves, we need ensure that they are doing their individual jobs for the AC to DC switch. Well let's take a look. http://forums.sohc4.net/index.php?topic=67543.0, https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book, Someone took this pic of me before I became a. Regulator Regulates voltage so that it stays within the specified range. The Cycle X "high-output" charging systems will allow you to use many . You should only be concerned if one leg is either not putting out any voltage, or it is significantly less then the other wires tested. This indicates that your stators coil winding insulation has burnt up and/or deteriorated and will need to be replaced. Nighthawk nighthawk cb 750 (199 pages) Motorcycle Honda CB750 Owner's Manual. Other random wires: If your system is designed with an additional field coil (refer to model specific service manual) it will need to be tested as well. In which case the stator has begun to break down or is bad. When I first got it, it ran great if started in hot weather. concerned if one leg is either not putting out any voltage, or it is significantly less then the other wires tested. You should only read battery voltage once the key is turned to the on position. Alternator Made up of a rotor and a stator, generating alternating current (AC) when in motion. JavaScript is disabled. You may also get a very high resistance reading. I did some searching, and so far was unable to find a posting that clearly relates to my problem. *Results: Since this wire needs a external signal. If it doesn't then you might have to start tracing physically. You repeat this three times two check all three wires. . It may not display this or other websites correctly. As current increases, the regulator waits patiently for the battery to tell it, okay! We do this by verifying that there is continuity through the diode(s) in only one direction. Add to Cart. It is caused by the charging system surging. I started having issues with it last year and since then I have replaced the voltage rectifier, the rotor, the stator generator, the carbon brushes and The battery. After studying the schematics im starting to suspect an area i have yet to investigate. Place your meters black (-) lead to a solid ground. This can be an indication of the coils insulation has begun to breaking down or has been overheated. (101 pages) Motorcycle Honda CB750F2 Owner's Manual. Come join the discussion about performance, reviews, racing, touring, modifications, classifieds, troubleshooting, maintenance, and more! Staff member. Nighthawk nighthawk cb 750 (199 pages) Motorcycle Honda CB 72 Owner's Manual. To accomplish this switch, the rectifier is made up of diodes. I will go pull the cover now and test the contact rings directly now. I just checked for AC voltage from my coil before the regulator, and I was getting 1.0 vac at 5000 rpm. Can someone please help me, I sure would appreciate . #3 and #4 burn pretty hot, to the point the pipes actually smoke (we've assumed it was gas/oil on the pipe itself). You can do this test by first setting your multimeter to read AC voltage. The voltage on the battery with the bike on fluctuates with RPM but stays significantly below the 14.5 I expect to see. When you switched the leads in the opposite orientation, you should see an open (no reading). Cycle Forums: Motorcycle and Sportbikes Forum. First, I'm not receiving any compensation. Good luck D Darryl thompson CB750 New member Messages 4 Reaction score 0 Points 1 Location Madras or 97741 Aug 21, 2022 #3 Changed voltage regulator - did not help. Plus he offers a LIFETIME WARRANTY. BIKE WON'T HOLD 13/14 VOLTS. This did not work for me, I have the same problem but with cleaner carbs. I bought a 1981 CB750 last fall. Please let me know how your stator works out as soon as you know. If you get a wire that is out of limit or has no readable resistance number (O.L). with insulated leads & 1pc. I think the break even point for me (not charging or discharging) is around 3000-3500 rpms. *Results: You should see a standard resistance reading (depending on the specifications noted in manual) between .001 up to .9 . OK, I just tested and got 59 ohms between the 2 brush wires. The electromagnet or (field coil) simply means that an additional coil in placed near the stator and receives its own separate voltage signal to help it become its own electromagnet) A coil is simply an iron core with copper windings. Like 850 outbound clicks to CB750C.com WEEKLY. Ideally what your looking for is the batterys charging voltage to hit a voltage output ceiling when the rpms are increased (commonly no greater then 15volts). Use one meter to check the DC voltage across the battery terminals. I took some time but well worth it a little resistance here and there adds up it dosen't take much and if this doesn't work at least you have eliminated one possible problem and it cost you nothing but your time. Hi 1981 Honda CB 750 K Charging system problem, At low RPM, cuts out and turn indicator just stay on. Use that. Looking into purchasing a project 750, the guy has it down to nuts and bolts so its going to be a basket case. Now rev the motorcycles rpms up to around 3,000 rpms and hold. CB750 New member. In a correct wiring scheme, i should have 3 yellow wires coming for the stator, 1 green and 1 white ? yeah i just did that too. Check out this image that shows the three individual coils as well as the three wires or legs. There are six diodes total. Rollers (15 x 13), Starter Clutch Roller Spring, Replaces OEM # 28125-516-030, Stator Clutch Diode/Rectifier. Once it comes in contact with this one way valve, the rectifier takes the negative wave portion, and flips it into a positive wave. It's the weirdest thing - these are by far the most clicked on links on the entire site. *Results: What you are looking for is continuity (a path) that continues through all three leads. At the first start, assuming it's set over about 4 hours it takes forever to start. I use one like this that gives you a Digital voltage read out. Thread starter MIkeZad; Start date Jul 2, 2021; M. MIkeZad CB750 New member. The stator needs to be replaced. Shows Voltage of your alternator rising and falling with RPM and gives a clear indication of your charging systems normal operation and early warning of problems. Wow, looks like I am not the only one with problems. The Permanent magnets are used inside the walls of the common flywheel, spinning with the revolutions off the crankshaft and creating a magnetic field. Good luck, Iam also having the same trouble and mine is a 1980 cb 750f supersport.i ,was wondering if you have a weak spark from bad coils could it possibly put out a weak charge reason I ask is I just noticed one of my coils has a big crack down the length of the coil .I'm sure it s not a good thing but .could it play a role in my charging issue any help is welcome .I'm tired of charging battery all the time.open for new ideas please help me save this ol bike. possibly a bad volage regulator? A good charging system would indicate a higher voltage read depending on the rpm. I need to look somewhere else to find my issue. I am thinking vacuum or gas but I am stumped. This changes the AC wave to a direct (more controlled) voltage signal. hondatwins.net is not in any way affiliated with Honda Motor Company, VerticalScope Inc., 111 Peter Street, Suite 600, Toronto, Ontario, M5V 2H1, Canada. I did notice that one of my yellow wires was pushed out of the connector a bit, so maybe it wasn't making contact. Alternator Rotor Puller - 20mm x M1.5 Right Hand Thread Puller for pulling internal thread rotors. Use United States (US) dollar instead. I use these almost everyday Im on the job. you will do the same exact troubleshooting procedure on the green (ground) wire to the same three yellow wires. John DeMaria's '74 CB750K Happy Customers 8782808780 Since 2010 Important Product Safety Notice Series 1: Electrical Ignition Systems, Ignition Switch, Coils, Plugs, Contact Points Headlamp, Bulbs & Parts Turn Signal Lamps, Stems, Lenses & Reflectors Tail Lights - OEM Type Tail Lights - Aftermarket/Custom Switches & Sensors Handlebar Switches Repeat this two more times, only moving your black test lead to the other yellow wires. They are not serviceable, and if a problem is found with either systems. Anyone? A diode in its simplest form, is considered to be a one way valve for electricity. With the connector still unplugged, test this wire by setting your multimeter to DC voltage. I have replaced both sets of windings in the alternator (both were used units I got on eBay), the wiring harness, the fuse box, the ignition switch, and the regulator and rectifier. 4. Ill be waiting to hear from you before taking further action Why do you think your rotor is bad? . For a better experience, please enable JavaScript in your browser before proceeding. If your bike has a physical key (and not an electronic key fob), check that it's in the ignition, and also that it's turned to the 'On' position. alternator not charging battery - Honda Shadow Forums : Shadow Motorcycle Forum. Generally anything below 8mm is an indication of a worn brush. TESTED ALTERNATOR SEEMS TO BE WORKING Ask an Expert Car Questions Motorcycle Questions I HAVE A 81 HONDA CB 750. Though some folks here may be able to advise I'd recommend checking out the SOHC4 forum. Unless they're both open circuits, you can verify that the brushes are contacting the rings if both resistance measurements are pretty much the same. That means, that I have to charge the battery fully to use it again. Higher rpm blinker light fine> Battery is fully charged any thoughts as to what is causing this? You are using an out of date browser. It's a PITA trying to deal with this system. 10VAC sounds a tad low. Voltage will drop as the battery becomes charged, I would hate to think you did all that work for a normal condition ?? The 3 male spade connectors plug in where the old regulator connected. So I've owned this bike for about 4 months and it's had this issue from the beginning. This outcome needs to be the same on every diode you test. With the bike running at operating temperature. 1981 HONDA CB650Z / A - chain drive 1981 HONDA CB750F/F2 . Dismiss. thank you, Rotor can fail when hot. TESTING REGULATOR FUNCTION AT THE BATTERY. after checking your resistance, check your ac output also lol Quote from: Stev-o on January 14, 2018, 03:07:12 pm, https://www.youtube.com/watch?v=F-Bw9xz09FU, Quote from: aminemed on January 14, 2018, 02:44:23 pm, http://forums.sohc4.net/index.php?topic=126401.0, http://forums.sohc4.net/index.php?topic=132935.0, https://www.cmsnl.com/classic-honda-fansite/honda_wiring_diagrams/CB750(K3-K7).jpg. 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Allow you to use many links on the entire site so that it stays within the range! Components part by part in the most clicked on links on the battery with the red ( + lead. To find my issue Puller for pulling internal thread rotors come join the discussion performance.