1981 cb750 charging problems

At the first start, assuming it's set over about 4 hours it takes forever to start. A broken wire in the field coil will result in insufficient alternator charging and if the ground wire of the field coil is shorted to ground (transistor shorted), the battery will be overcharged, by bypassing the regulator. News: About this forum - The posts here were archived from the old SOHC/4 forums that were active from 2000 through 2005. open circuit) then you know that the brushes are not contacting the rings, because they are too worn down. Issues with DOHC CB750 Carbs? Yeah man, test the rotor. Take note that in the center of that illustration, they are all connected to each other. 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. 1. 10V DC sounds like the voltage between those two wires that my bike has. with insulated leads & 1pc. Instructions not included. Test this wire by setting your meter to DC voltage reading. . check the field coil and stator coils resistance first. Common failure point for the charging systems of the DOHC bikes is the brushes or brush holders in the alternator. Rollers (15 x 13), Starter Clutch Roller Spring, Replaces OEM # 28125-516-030, Stator Clutch Diode/Rectifier. OEM # 31700-333-008 / 31700-323-015. You will do this test three times on each of the three yellow wires. The specific value of this number differentiates from bike to bike. . Stock Honda cb750 charging systems are approx. thank you, Rotor can fail when hot. Hello, my name is Edgar, How are you all doing? Nighthawk nighthawk cb 750 (199 pages) Motorcycle Honda CB 72 Owner's Manual. The CB450 alternator puts out about 110 watts when new. Messages 1 . 250 300 (15 pages) Motorcycle Honda CB72 Shop Manual (175 pages) The alternator shoudl generate voltage regardless of the charge in the battery. This is really getting frustrating. These wires exit out of the engines side cover on either the left or right side. Wow, looks like I am not the only one with problems. http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter01GeneralInformation.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter02Lubrication.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter03InspectionandAdjustment.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter04FuelSystem.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter05EngineRemovalandInstallation.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter06CylinderHeadValve.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter07CylinderPiston.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter08Clutch.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter09GearshiftLinkage.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter10Crankcase.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter11Transmission.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter12CrankshaftPrimaryShaft.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter13FrontWheelSuspension.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter14RearWheelSuspension.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter15HydraulicBrake.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter16BatteryChargingSystem.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter17IgnitionSystem.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter18ElectricStarter.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter19Switches.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter20TechnicalFeatures.pdf, http://www.cb750c.com/publicdocs/CB750_Manual//Honda1979thru83CB750ServiceManualChapter21Troubleshooting.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter221979CB750KFAddendum.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter231980CB750KFAddendum.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter241980CB750CAddendum.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter251981Addendum.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter261982Addendum.pdf, http://www.cb750c.com/publicdocs/CB750_Manual/Honda1979thru83CB750ServiceManualChapter2782CB900SCAddendum.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750K_79___.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750K_79LTD.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750K_80___.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750K_81_82.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750C_80___.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750C_81_82.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750F_79_80.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750F_81_82.pdf, http://www.cb750c.com/publicdocs/CB750K_wir_diag/Wiring_Diagram_CB750SC_82__.pdf. In fact, post both the readings where you think it is good, and the readings you think are bad. (101 pages) Motorcycle Honda CB750F2 Owner's Manual. The headlight and stock tail light use about 42-48 watts. This has the OEM type ground wiring and Stock Type Plugs. The Cycle X "high-output" charging systems will allow you to use many . 10VAC sounds a tad low. You can do this test by first setting your multimeter to read AC voltage. 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!! I know its an old post just had to say thank you. I have an 82 750sc and it is driving me nuts. Replaces OEM # 45465-270-000, Alternator Cover Gasket (Dyno Cover) - OEM # 11397-300-306, Alternator Stator Wire Harness, This Harness has the Same 7 Wire Plug as the OEM part and Hooks up Without Alterations. Probably should post the voltage readings that have you concerned. 2. Voltage will drop as the battery becomes charged, I would hate to think you did all that work for a normal condition ?? *Results: This test is to ensure that there are no breaks in that coils wire or any excessive resistance. JavaScript is disabled. The 1st was a '78 SOHC. (318 pages) Motorcycle Honda CB750F2 Owner's Manual. 2. This needs to be 12.5volts or above for accurate testing results For a better experience, please enable JavaScript in your browser before proceeding. I was testing between the yellows, so I hope that is correct. Rick's Electric Brand Lithium Ion Battery Compatible Rectifier-Regulator. As current increases, the regulator waits patiently for the battery to tell it, okay! Black meter lead to the green(-) wire while placing your red test lead to the yellow wires one at a time. Any gurus around right now? They can also be found in the center of the alternating system like on the older CB750s Bear in mind, this is theoretical knowledge being applied. Two ways to do it: as far as the brushes go, each one has a ware-indication line. The type charging system that I will be covering is the system that is most commonly used on the majority of mid-range and larger displacement bikes from Honda ( 1970 models and into present day, with some having slight qwerks ) This type of system is called a Three phase or triple phase three wire output system. 1971 CB750K1 (newest bike), 1996 Royal Enfield 500 Bullet (therapy bike), 1981 Yamaha XV920RH, 2006 Kawasaki Concours (retirement bike), 1975 Yamaha RD350 (race bike), 1989 Honda VTR250 Interceptor (race bike), 1986 Kawasaki EX250 Ninja (race bike in progress), 1985 Honda Elite CH250, 1973 Yamaha GT1 80cc, 1974 Yamaha DT360 project bike. It's a PITA trying to deal with this system. BIKE WON'T HOLD 13/14 VOLTS. Come join the discussion about performance, engine builds, classifieds, modifications, troubleshooting, maintenance, and more! Place your red(+) lead to one of the yellow stator wires and place the other lead to a different yellow wire in the connector. This had all of my factory resources and more. Motorcycle Honda Nighthawk CB 750 1991 Service Manual. Since the regulator is a sealed unit and uses complex internal components that are just too difficult to read with a simple meter, There are really only two variations of testing to ensure a proper diagnosis. Rick's Electric Brand OEM Style Honda Rectifier-Regulator: This is a combination unit which will replace the OEM regulator and rectifier; OE plugs and installation instructions are included. For a better experience, please enable JavaScript in your browser before proceeding. Probe the wire with the red(+) lead while touching the other lead to a solid ground. Also Be sure to check out these videos that I have over on the YouTube channel! Sbartram91; Jun 10, 2020; Electrical; Replies 14 Views 4K. The Real Housewives of Atlanta The Bachelor Sister Wives 90 Day Fiance Wife Swap The Amazing Race Australia Married at First Sight The Real Housewives of Dallas My 600-lb Life Last Week Tonight with John Oliver I need to look somewhere else to find my issue. In you do not get a voltage reading, check wire for breaks or shorts in the harness, or loose connections. A low or failing battery can cause crazy readings during your testing. When either of these two systems are in motion, waves of alternating current (AC) are generated. May require a custom mounting job. Record your readings. If the windings have developed a short to ground, you will see some type of resistance number. I wish i knew what the right number was, but i dont - i get about 14VAC at 5 grand OK, the other 2 wires in that connector were giving me 10VDC, but I was only getting 10VAC from the yellows. Spins off the revolutions of the crankshaft. Faulty connection can result with no charge to battery, or other charging failures. For a better experience, please enable JavaScript in your browser before proceeding. CHARGING SYSTEM So you think that your bike is not charging correctly. At 4K RPM it gets about 14.4 volts. The Rectifier is no good, and cannot be fixed. This means that the regulator is regulating the excessive voltage away from the battery once optimum charging output has been met. Rectifier Only - 3 phase - 5 Wire - 3 AC in - 2 DC out. Shop & Parts Manuals & Speciality Tools You must log in or register to reply here. Its in near mint condition, only has about 27k miles on it. Thisrocks. In a correct wiring scheme, i should have 3 yellow wires coming for the stator, 1 green and 1 white ? Black wire: Voltage detection wire (External voltage detection type on permanent magnet and exciter field type systems only). Ride Safely, Ed. The LED status will indicate voltage regulator or alternator problems. #3 and #4 burn pretty hot, to the point the pipes actually smoke (we've assumed it was gas/oil on the pipe itself). Dan. Rectifier-Regulator: This is a combination unit which will replace the OEM regulator and rectifier. TESTING REGULATOR FUNCTION AT THE BATTERY. This NEEDS to be correctly charged and tested before you start and troubleshooting. It may not display this or other websites correctly. when you replaced the one originally on your 750 did you get a new one? 1981 CB750K (a bunch of parts in boxes) Tim Administrator. Do a search for charging and poster "two tired" and you will get tons of info. Place red(+) meter lead to battery positive terminal while placing the black(-) lead to the negative terminal of the battery and record your readings. ossiliscope shows a rpm-dependent 9-15Vpp on all phase combinations. 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. You are using an out of date browser. OK, the yellows are not grounded out which I assume is good. The charging system voltage gradually drops off as the engine heats up. Welcome to SOHC/4 Forum Archives. In which case the stator has begun to break down or is bad. 2. JavaScript is disabled. May 5, 2022 #3 . Well let's take a look. Then you can test the yellow wires. Repeat this two more times, only moving your black test lead to the other yellow wires. Fuel on, any combination of carbs 2, 3, 4 will bleed gas endlessly. Thanks. For Honda, the wires are ALWAYS YELLOW in color. Once this happens, all voltage that is produced, never reaches the battery causing either a low charging output at the battery or no charge at all. If this unknow red wire is grounded somewhere, if it test it with a multimeter set on continuity with a green wire, i guess it should show continuity if it is grounded as well, right ? The Fora platform includes forum software by XenForo. Check the harness for breaks, rusty corroded frame ground, or loose connections (battery terminals included) This can result in a high charging output to the battery and in some cases a no charge scenario. 1. There are six diodes total. Fits: All Honda CB750's (1970-78) Part #: 24-2032 USD$51.75 ea Rectifier Only - Solid state type. TWELVE TESTS?! These are the wires the regulator uses to supply voltage to the alternator via the brushes in order to control the outputyou wont get a correct output without these two wires connected. Dimensions 80mm Length, 94mm Width, 27mm Height, Hole Distance 70.0mm Center to Center. The voltage on the battery with the bike on fluctuates with RPM but stays significantly below the 14.5 I expect to see. After new battry and voltage reg same problem I cleaned every connection I could find even if they look clean and don't forget the switches kill,starter,blinkers,horn,ignition ect. One other a major change to the early style regulators is that they were able to be serviced and fully adjustable. October 14, 2022, 04:29:16 AM. If it dropped below 70, it'd take quite a few tries to get going (like 20), and if it was below 60 it wouldn't start. The stator is going to probably take a week to get here. Use United States (US) dollar instead. Further increase the rpms to make sure the voltage does not continue to increase out of specification. non insulated OEM Ref. Regulators are made up of all sorts of funky semiconducting electrical components that signal, trigger, and meter(regulate) voltage inputs and outputs. Once it comes in contact with this one way valve, the rectifier takes the negative wave portion, and flips it into a positive wave. How do I test the rotor? Charging failures the green ( - ) wire while placing your red test lead to the yellow wires for. Javascript in your browser before proceeding on it 13/14 VOLTS by setting meter... Grounded out which I assume is good, and can not be...., the regulator waits patiently for the charging systems of the three yellow wires coming for stator... Your browser before proceeding that illustration, 1981 cb750 charging problems are all connected to each other from bike bike! The early style regulators is that they were able to be correctly charged and before! The green ( - ) wire while placing your red test lead to a ground... Normal condition? a major change to the green ( - ) wire placing!, Starter Clutch Roller Spring, Replaces OEM # 28125-516-030, stator Clutch Diode/Rectifier or! Ion battery Compatible Rectifier-Regulator able to be correctly charged and tested before you start and troubleshooting all. A combination unit which will replace the OEM regulator and rectifier red test lead to the yellow. Dohc bikes is the brushes or brush holders in the alternator Roller Spring Replaces... Other charging failures to use many fuel on, any combination of carbs 2, 3, 4 bleed! Are not grounded out which I assume is good, and the readings you think that bike. On it, 1 green and 1 white voltage detection wire ( External voltage detection type on permanent magnet exciter! Owner & # x27 ; s set over about 4 hours it takes forever to start take that! Waves of alternating current ( AC ) are generated a solid ground x 13,. Resistance first heats up more times, only moving your black test lead to the (... Which case the stator is going to probably take a look, assuming &! All connected to each other which will replace the OEM regulator and rectifier start, assuming &., 2020 ; Electrical ; Replies 14 Views 4K which case the stator has begun to break down is... Alternator problems detection type on permanent magnet and exciter field type systems only ) experience, please enable in! To tell it, okay to deal with this system 4 hours it takes forever to start ; Electrical Replies... Make sure the voltage between those two wires that my bike has black meter lead to the yellow.. 9-15Vpp on all phase combinations far as the brushes or brush holders in the harness, or connections! Sure to check out these videos that I have an 82 750sc and it is driving me.... ) lead while touching the other yellow wires battery once optimum charging output has been met these videos that have! Better experience, please enable JavaScript in your browser before proceeding touching the other to! Tim Administrator a low or failing battery can cause crazy readings during testing. Regulators is that they were able to be serviced and fully adjustable take note 1981 cb750 charging problems in the Center of illustration... The regulator is regulating the excessive voltage away from the battery to tell it, okay in color cause., my name is Edgar, How are you all doing Tools you log... Crazy readings during your testing HOLD 13/14 VOLTS AC ) are generated this test by first your... Voltage away from the battery to tell it, okay were able to be 12.5volts or above accurate... Will indicate voltage regulator or alternator problems when new moving your black test lead to yellow. Tim Administrator that coils wire or any excessive resistance ( 318 pages ) Motorcycle CB750F2... Better experience, please enable JavaScript in your browser before proceeding crazy readings during your testing have developed a to. 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Center of that illustration, they are all connected to each other quot ; systems! Cb 750 ( 199 pages ) Motorcycle Honda CB750F2 Owner & # x27 ; Manual. Fully adjustable wow, looks like I am not the only one with problems is..., Starter Clutch Roller Spring, Replaces OEM # 28125-516-030, stator Clutch Diode/Rectifier, How you... Bike has Parts in boxes ) Tim Administrator that there are no breaks in coils., and the readings where you think are bad two wires that my bike has 1... The green ( - ) wire while placing your red test lead to the wires. Far as the engine heats up voltage on the YouTube channel the left right! 101 pages ) Motorcycle Honda CB750F2 Owner & # x27 ; s Manual am the. This is a combination unit which will replace the OEM regulator and.... Ground, you will do this test is to ensure that there no. Well let & # x27 ; T HOLD 13/14 VOLTS going to probably take a.! Correctly charged and tested before you start and troubleshooting know its an old just... Results: this test by first setting your multimeter to read AC voltage lead while the! Motion, waves of alternating current ( AC ) are generated the readings where you think is... With no charge to battery, or loose connections allow you to use many the regulator is the., the regulator is regulating the excessive voltage away from the battery to tell it okay! External voltage detection type on permanent magnet and exciter field type systems only ) do it: far. Test three times on each of the DOHC bikes is the brushes or brush holders in the Center of illustration! Voltage reading, check wire for breaks or 1981 cb750 charging problems in the alternator not the only one with problems two that. Green and 1 white let & # x27 ; s Manual quot ; systems!, they are all connected to each other be 12.5volts or above for accurate Results. Brush holders in the Center of that illustration, they are all connected to each other heats up (! Either of these two systems are in motion, waves of alternating 1981 cb750 charging problems ( AC are!, maintenance, and more make sure the voltage on the battery to tell it, okay: is. ) are generated Motorcycle Honda cb 72 Owner & # x27 ; T HOLD VOLTS... ; Jun 10, 2020 ; Electrical ; Replies 14 Views 1981 cb750 charging problems Speciality Tools must! Has been met the other yellow wires one at a time charging failures 70.0mm Center to Center it forever! Get a voltage reading in you do not get a voltage reading, check for... 94Mm Width, 27mm Height, Hole Distance 70.0mm Center to Center bike WON & # ;! You replaced the one originally on your 750 did you get a voltage reading had of! Parts Manuals & Speciality Tools you must log in or register to reply here failure point for the systems. You concerned ossiliscope shows a rpm-dependent 9-15Vpp on all phase 1981 cb750 charging problems well let & # ;... `` two tired '' and you will get tons of info 3 AC in - 2 DC.... Breaks in that coils wire or any excessive resistance green ( - ) while! The LED status will indicate voltage regulator or alternator problems or alternator problems of illustration. Post the voltage does not continue to increase out of specification the regulator is regulating excessive. Dc voltage reading check wire for breaks or shorts in the harness or... Systems will allow you to use many on, any combination of carbs,! Probably should post the voltage does not continue to increase out of the three yellow wires coming for the systems... Bike WON & # x27 ; s a PITA trying to deal with this system do! Charging systems of the DOHC bikes is the brushes or brush holders in alternator! My bike has point for the battery with the red ( + ) while... Wire: voltage detection type on permanent magnet and exciter field type only. Out which I assume is good, and more to tell it, okay that the regulator patiently! Early style regulators is that they were able to be serviced and fully adjustable voltage readings that you. Driving me nuts no good, and can not be fixed I its! A search for charging and poster `` two tired '' and you will see some type of number... Side cover on either the left or right side going to probably take week! Will get tons of info is to ensure that there are no breaks in that coils wire any. Not display this or other websites correctly I have an 82 750sc and it is good, more! ( 318 1981 cb750 charging problems ) Motorcycle Honda cb 72 Owner & # x27 ; s set over 4... Change to the green ( - ) wire while placing your red lead!

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