The "proper" way to test a charging system is to use a two meter test. The voltage on the battery with the bike on fluctuates with RPM but stays significantly below the 14.5 I expect to see. I googled it for issues with it and itll say to replace those if they were bad. thank you, Rotor can fail when hot. These readings should be closely in range of each other. Some more pics, checked everything again: After reading in the forum, it seems that the first issue to check if my battery voltage is not increasing with the rpm is the alternator. My battery is not fully charged right now, so I am guessing that would be part of the problem with only getting 10vac. I've had it for 2 years, and for about 1.5 of those years, I had no issues. The alternator shoudl generate voltage regardless of the charge in the battery. So I bought a 1981 CB750 about a year ago. Motorcycle Honda Nighthawk CB 750 1991 Service Manual. Well let's take a look. *Results: The goal here is to make sure that a resistance reading is noted in only one direction of each diode. Cold starting issue with 81' CB750. 2. The rectifier is bad and will need to be replaced. The voltage on the battery with the bike on fluctuates with RPM but stays significantly below the 14.5 I expect to see. The whole unit must be replaced as one. Yeah man, test the rotor. After installing, I had a constant voltage @ 14v. You repeat this three times two check all three wires. The lights were bright with no fading based on the idle. Messages 4 Reaction score 0 Points 1 Location London. possibly a bad volage regulator? could be that, theoretically. Sbartram91; Jun 10, 2020; Electrical; Replies 14 Views 4K. . *Results: Since this wire needs a external signal. Assuming the field coil is actually making the same strength field in which the rotor spins within, if the rotor has lost permeability, then the stator will see less flux lines crossing its windings, reducing it's output strength. I would like to start running it through the electrical troubleshoot, but first i have a question I know that the first step is to read voltage when engine is at 2000 rpm, 3000 rpm, etc. Exceptional compilation, thanks. I dont care how small of a decimal reading you see, it still should read as if it was an open wire. Since AC current is alternating back and forth from positive to negative in its own waveform. So I've been working on my CB for the past few weeks in an attempt to get it to charge normally again. If not, check for breaks in the harness, or loose connections. I use one like this that gives you a Digital voltage read out. Stop Light Switch Adjustment. Recommend you use the CB1000C Chapter 18 for the Battery and Charging System instead of the 750 Chapter 16 as it is more informative and has the rotor measuring picture and information . Do this with all three of the yellow wires. Dan. Plenty videos on u tube. May require a custom mounting job. The Fora platform includes forum software by XenForo. CB750 charging problem HELP!! Typically the regulator utilizes 3 to 4 different wires to function properly. Talk to Tony at Oregonmotorcycleparts.com. OEM # 31700-333-008 / 31700-323-015. HAVE A CHARGING PROBLEM. The red wire goes from this fuse to the fuse panel in the handlebars, and if that is the only wire that shorted, it should be not too difficult to fix. But, see with the meter where it does go. It kind of just sound like the motors turning over slow and the longer you hold the start button the closer it gets until it finally starts . This more than likely means that there is a break in the windings. Set your multimeter to the resistance (ohms ) setting. Honda cb750 sport motorcycle owner's manual (90 pages) The Cycle X "high-output" charging systems will allow you to use many . 1981 CB750K (a bunch of parts in boxes) Tim Administrator. TESTED ALTERNATOR SEEMS TO BE WORKING Ask an Expert Car Questions Motorcycle Questions I HAVE A 81 HONDA CB 750. JavaScript is disabled. 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. In a correct wiring scheme, i should have 3 yellow wires coming for the stator, 1 green and 1 white ? HAVE A CHARGING PROBLEM. 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. I've got a new set, but I may have to solder the dog legged one to make it work. Come join the discussion about performance, engine builds, classifieds, modifications, troubleshooting, maintenance, and more! Once this signal is read, the regulators job is to either send the excessive voltage straight back to where is came from, short it to ground, or send a signal telling the field coil to stop its output. With the bike running, test all three for AC voltage with a multimeter. It allows voltage to pass through it but does not allow voltage to reverse its direction back the other way. That means, that I have to charge the battery fully to use it again. JavaScript is disabled. When either of these two systems are in motion, waves of alternating current (AC) are generated. Trouble shoot your charging system with a quick glance at the LED lights on this small 1 5/8" x 1" unit. Never been laid down or anything of that sort. Apr 08, 2010 2003 Honda CB 750 Nighthawk. 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. Regulator Regulates voltage so that it stays within the specified range. Thread starter MIkeZad; Start date Jul 2, 2021; M. MIkeZad CB750 New member. Your alternator has to pass AC voltage before the rectifier/regulator can do its work. We know that current is produced from the spinning motion of the alternator, as RPMs increase so does the AC voltage output. This had all of my factory resources and more. Dimensions 68mm Length, 94mm Width, 26mm Height, Hole Distance 80.0mm Center to Center. JavaScript is disabled. 4. 1981 HONDA CB750F SS (By ED VILLANUEVA, 2013-10-19) carb flooding (By Jonny Honda, 2013-09-08) RE: carb flooding (By Darryl h thompso, 2021-09-28) Wendy (By Wendy, 2013-09-07) 81 CB750 Chopper (By Paul, 2013-08-01) Type of oil and brake fluid (By Juan Nobles, 2013-07-26) Bill Hall (By seger, 2013-07-22) HIGH RPMS ON HIGHWAY (By JASON, 2013-06-17) Continue Reading. Like 850 outbound clicks to CB750C.com WEEKLY. The main thing that will go wrong with the charging system is the rotor. With the stator harness connector still unplugged and your multimeter still in the resistance () setting, place your red (+) lead to each of the yellow wires while grounding the black (-) lead to a solid ground. Welcome to SOHC/4 Forum Archives. Start your motorcycles engine and place your red (+) lead to either one of the three yellow wires by back probing into the connector. Its pretty crazy. Another thing that is a problem area is the cam chain . With the connector still unplugged, test this wire by setting your multimeter to DC voltage. Changed voltage regulator - did not help. Now switch your meter leads and retest. All these wires are then connected to a big plug which is located on the main harness. By Mc Staff. Black meter lead to the green(-) wire while placing your red test lead to the yellow wires one at a time. check the field coil and stator coils resistance first. Anyway the DOHC CB 750s are known for really bad electrics. For a better experience, please enable JavaScript in your browser before proceeding. You should only read battery voltage once the key is turned to the on position. Nighthawk nighthawk cb 750 (199 pages) Motorcycle Honda CB750 Owner's Manual. At the first start, assuming it's set over about 4 hours it takes forever to start. Too much charge can cause overheating, meltdowns, explosions, and fires. Any gurus around right now? Test this wire by setting your meter to DC voltage reading. Keeping money in your pocket from avoiding the shot-gun approach whenever a charging system problem arises. 250 300 (15 pages) Motorcycle Honda CB72 Shop Manual (175 pages) At my wits end with these carbs. The stator is going to probably take a week to get here. enough is enough!. Almost all reg/recs now-a-days are combined into one sealed unit. When you purchase through links on our site, we may earn an affiliate commission, which supports our community. non insulated OEM Ref. I HAVE A 81 HONDA CB 750. If the regulator is receiving all of its signals to operate but you still have a no charge at the battery, the regulator/rectifier may not be the issue. The brushes are easy to come by, but the holder is not. The LED status will indicate voltage regulator or alternator problems. There are six diodes total. yeah i just did that too. For the other, you would use preferably an amp clamp on the + battery cable. A forum community discussing all bikes from Harley Davidson to Honda, Suzuki, KTM, Yamaha, and BMW. Check the Forum FAQ before you post - the answer to your questions might already be there waiting. You are using an out of date browser. 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. TWELVE TESTS?! open circuit) then you know that the brushes are not contacting the rings, because they are too worn down. There are several available in the aftermarket though. OEM # 31700-124-003 / 31700-166-008, Rick's Electrics Starter Motor, Replaces OEM# 31200-300-030, Starter Motor Seal - Size 24.4 x 3.1, Replaces OEM# 91312-MG7-003 / 91309-300-000 / 91309-425-003, Starter Motor Seal - 60 x 1.4 - Replaces OEM# 31206-286-158 / 31206-402-008, Replacement Starter Brush (Set/2) 12mm x 14mm x 6mm Brush for Mitsuba 2 brush Starter - 1 pc. Good luck D Darryl thompson CB750 New member Messages 4 Reaction score 0 Points 1 Location Madras or 97741 Aug 21, 2022 #3 I will replace this one soon with a better shot! #3 and #4 burn pretty hot, to the point the pipes actually smoke (we've assumed it was gas/oil on the pipe itself). Replaces OEM # 95700-06056-00, Front Cable Clip, This Clip Holds the Stop Switch Wires to the Cable to Keep Things Tidy. the bike quit charging the battery 20 years ago after jumping it with a car, parked it in - Answered by a verified Motorcycle Mechanic. Now I'm stuck. Use that. Instructions not included. (30 pages) Motorcycle Honda CB750 Shop Manual. Thisrocks. Thanks Janie Answered in 8 minutes by: Motorcycle Mechanic: .. Brian : Good day and welcome to Just Answer. Regulates AC output voltage and rectifies charging current. I have measured voltage at battery POS and NEG. 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. You should find this site helpful https://www.chinonthetank.com/2011/08/79-82-honda-cb650-charging-problems/ It's for a CB650, but it should still work. When you switched the leads in the opposite orientation, you should see an open (no reading). When you purchase through links on our site, we may earn an affiliate commission, which supports our community. The rectifier needs to be unplugged with no voltage running through it. Can someone help me? Rick's Motorsport Electrics has been producing high quality OEM style field coil charging rotor for Honda motorcycles for over 30 years. With the bike running at operating temperature. $ 349.00 . - Honda CB 750 question. The headlight and stock tail light use about 42-48 watts. im gonna hook the ac gen up to an oscilliscope and see wtf's goin on. stop losing sleep!just check those resistances. Place one lead on the wire and the other lead to a solid ground. 22v at idle up . CruiserForums Moderator - Route 66 / American Iron / The Clinic Forums. 2. They are broke down in chapters for easier downloading. I believe that bike is one of the early line of DOHC fours. All three should indicate roughly the same amount of AC voltage. Motiva, I am having the exact same problem with my 1980 CB 750, I took apart the carbs and cleaned the hell out of them, there are some great videos on youtube that give detailed instructions. Check out this image that shows the three individual coils as well as the three wires or legs. Remember, this is AC so you don't want frame ground on the meter while testing. Here is a link to a CB 750 forum that covers the DOHC CB 750s. JavaScript is disabled. The rest is left to run the ignition system and charge the battery. i think my problem is in the rotor rather than the stator. Registered so I could say thanks, maybe do my part to keep it up. Ill be waiting to hear from you before taking further action Why do you think your rotor is bad? I suppose that green ground wire was faulty and PO fixed it but with a red wire. Your right about the holder. Battery: This is a huge part of your charging system. Now reverse your leads and retest in the same manner as before. Sep 4, 2020. To little charge will gradually kill your battery. With it connected I was getting 10vac @ 5000 rpm between the yellows. OK, I just tested and got 59 ohms between the 2 brush wires. May 5, 2022 #3 . It also appears the previous owner didn't know what he was doing with wirig, so I have some work ahead of me. #'s 31201-292-158 / 31201-MG9-004, Starter Motor Terminal (Cover) Rubber Boot. Here is a link to a CB 750 forum that covers the DOHC CB 750s. Battery Charging. This changes the AC wave to a direct (more controlled) voltage signal. I am thinking maybe my brushes are bad because 1 is a lot more worn down then the other. 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. Here is a video explaining this procedure. Batteries can not store AC voltage. This site is also a test bed for modifications and themes that might someday find their way to the . We use cookies to give you the best possible experience on our website. Rick's Electric Solid State type Rectifier unit. Probably should post the voltage readings that have you concerned. .It has been doing that ever since. 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!! Looking into purchasing a project 750, the guy has it down to nuts and bolts so its going to be a basket case. This NEEDS to be correctly charged and tested before you start and troubleshooting. Keep in mind that this process is happening faster then you can see. 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. When I first got it, it ran great if started in hot weather. A diode in its simplest form, is considered to be a one way valve for electricity. what kind of voltage do you get at the battery running ~4000 rpms? Years produced: 1976-78. Set your meter to read DC voltage. Volt Amp Ohm meter with diode and continuity test, Alligator clips help add extra hands to your testing scenario. Power: 39hp @ 7,500rpm (rear wheel , period test) Top speed: 97mpg (period test) Engine type: 736cc air-cooled OHC inline four. This charging problem started two weeks ago, and has managed to screw me pretty good. I did notice that one of my yellow wires was pushed out of the connector a bit, so maybe it wasn't making contact. High quality Part. It will instantly start draining the battery. If you discover that you have and open (no numeric value) or a excessively high reading. Any insights would be greatly appreciated. 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 ?
