CB750 Custom
in [Motorcycles Tips]
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From: lwatters38 on 13 Aug 2008 20:33 I have a 1981 CB750 Custom and the charging system I know is going bad could it also cause a high rpm miss? I've checked the plugs and they are in excellent shape I'm leaning toward the carbs need work,I'm interested in what others may think......
From: ~ on 13 Aug 2008 21:08 On Aug 13, 5:33�pm, "lwatter...(a)gmail.com" <lwatter...(a)gmail.com> wrote: > I have a 1981 CB750 Custom and the charging system I know is going bad > could it also cause a high rpm miss? Yes. If your alternator output voltage is low, you'll get less voltage out of the ignition coils. Try reducing the spark plug gap to .025 in. and see if that helps a little. It's hard to tell whether a problem is electrical or carburetion when the deposits on the inside of the spark plug is grey, but look at the very tip of the center electrode and the side of the ground electrode which faces it. If the spark plug voltage is correct, you will see that the electrodes are a uniform color all the way across, but if the voltage is low, the plug will just fire from the middle of the center electrode.
From: default on 14 Aug 2008 09:54 On Wed, 13 Aug 2008 17:33:06 -0700 (PDT), "lwatters38(a)gmail.com" <lwatters38(a)gmail.com> wrote: >I have a 1981 CB750 Custom and the charging system I know is going bad >could it also cause a high rpm miss? >I've checked the plugs and they are in excellent shape I'm leaning >toward the carbs need work,I'm interested in what others may >think...... Yes it can. Check the resistance of the alternator rotor. The resistance should be ~4-5 ohms. It isn't a definitive test though, since the windings can short and open as heat and vibration work on them. The usually fail shorted so the resistance will be low. (zero your ohm meter it is hard to get accuracy down in the low ohms - the leads and connections have to be rock solid) The rotors frequently short out on that model. They are reasonably easy to fix yourself if you are inclined to try it. Basically you pull off the rotor, pull off the slip rings, then separate the halves of the iron pole pieces. Inside is a mess of charred magnet wire. You remove that and rewind a coil for it. Costs about $20 for some magnet wire and about a day's work. I can provide more detailed instructions - I've done two rotors for that model already. Best price I could negotiate with a dealer in the US was $230 for a new rotor. I did find one in the UK for about $70 (new) several years ago. Magnet wire was cheaper. The stator can fail, but that's less likely - better chance of a bad regulator or connector. Stator coils are wound outside the alternator on a jig you have to build then inserted into the slots in the iron. -- ----== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.pronews.com The #1 Newsgroup Service in the World! >100,000 Newsgroups ---= - Total Privacy via Encryption =---
From: SAMMMM on 14 Aug 2008 21:20 what condition are the plugs? sooty? white and shiny? bubbled? (the insulator) that will tell a lot about the carbs. that's better than diving into them. look for poor connections in the electrical system. they'll take out the regulator, etc. good luck, sam <lwatters38(a)gmail.com> wrote in message news:6f4a7ff7-8423-40b5-8289-e23d2d3c3452(a)a70g2000hsh.googlegroups.com... >I have a 1981 CB750 Custom and the charging system I know is going bad > could it also cause a high rpm miss? > I've checked the plugs and they are in excellent shape I'm leaning > toward the carbs need work,I'm interested in what others may > think......
From: lwatters38 on 14 Aug 2008 21:25
On Aug 14, 9:20 pm, "SAMMMM" <zamm...(a)comcast.net> wrote: > what condition are the plugs? > sooty? white and shiny? bubbled? (the insulator) > that will tell a lot about the carbs. that's better than diving into them. > > look for poor connections in the electrical system. > they'll take out the regulator, etc. > good luck, sam > > <lwatter...(a)gmail.com> wrote in message > > news:6f4a7ff7-8423-40b5-8289-e23d2d3c3452(a)a70g2000hsh.googlegroups.com... > > >I have a 1981 CB750 Custom and the charging system I know is going bad > > could it also cause a high rpm miss? > > I've checked the plugs and they are in excellent shape I'm leaning > > toward the carbs need work,I'm interested in what others may > > think...... Plug are in excellent shape burning nice and clean..... |