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Posted: Wed Mar 10, 2010 12:21 pm Post subject: 79 CB750 a few questions
Hi, I have a few questions, been searching, reading, if you can shed some light for me, thank you!
My bike idles fine when cold, but sometimes wants to idle very high when warm. I can get the idle to drop by blipping the throttle, but this is causing a rideability issue for me. I have the idle speed adjusted to about 900/1000 (cold), but when it heats up and goes high it will only drop to 2-3000. Is this a manifold leak kind of thing? It doesn't misbehave all the time....
This morning, the bike wouldn't rev over about 6500 - it was just sort of suddenly choking out or exceeding it's ignition. Ran pretty good otherwise, but I tried to push it up there a few times and she wouldn't go. Reminds me of an electronic rev limiter. What's up with that?
Is anybody gonna be at Oley or Rhinebeck this spring, who wouldn't mind listening to my engine and telling me it's ok? I just don't really know what I should be hearing, and if I'm hearing things I shouldn't be.
Joined: Feb 04, 2007 Posts: 2318 Location: Studio City, Los Angeles, Ca. 91604
Posted: Wed Mar 10, 2010 1:49 pm Post subject:
Dave,
1st off and most importantly, your valves need to be adjusted.
Next your carbs need to be synchronized to your poorly running because it has been neglected engine.
Your charging system just took a dump on you and it is most likely the rotor that went bad.
If you want to give me a call so I can walk you through the tests to check your charging system if you have a digital multi meter, my numbers are;
818-769-5394
818-259-8690
Joined: Dec 23, 2009 Posts: 103 Location: West Sussex, England
Posted: Thu Mar 11, 2010 4:40 am Post subject:
Dave,
Sounds like it's running too lean but without knowing the state of everything else it would be difficult to diagnose, as Ray said there is a process of elimination that you will have to follow. If you haven't already called Ray I would as you will save time and money, both things that most of could do with more of.
Joined: Jul 31, 2009 Posts: 132 Location: so san francisco ca
Posted: Thu Mar 11, 2010 6:40 pm Post subject: Honda 750 idel
I would not blame the carbs until you check ingition and timing these bikes are very sensitive to point timing if your points are not opening enough or set wrong you will get bad running issues.Honda motors will start and run no mater how bad someone sets them up but to reach designed function at 9grand you have to have everything in proper setting.If ignition proves to be right on then move to carbs and yes check valves also set cam chain for tension you dont want motor to jump timing. Good luck Fast Honda California.I really think Honda motors are the best made in the 60s 70s
Joined: Feb 04, 2007 Posts: 2318 Location: Studio City, Los Angeles, Ca. 91604
Posted: Fri Mar 12, 2010 10:22 am Post subject: Re: Honda 750 idel
fasthonda wrote:
I would not blame the carbs until you check ingition and timing these bikes are very sensitive to point timing if your points are not opening enough or set wrong you will get bad running issues.Honda motors will start and run no mater how bad someone sets them up but to reach designed function at 9grand you have to have everything in proper setting.If ignition proves to be right on then move to carbs and yes check valves also set cam chain for tension you dont want motor to jump timing. Good luck Fast Honda California.I really think Honda motors are the best made in the 60s 70s
This is a DOHC Honda and it does not have points, it is electronic ignition and the timing gets set once at the factory and never ever under any circumstances touched again unless you are installing a Dyna 2000 programmable ignition system.
The problem on dudes bike now is the carbs and the charging system, there is no questioning me or my sound advice. _________________ Ray #1
71 CL350K3 Scrambler
79 CBX
10 VFR1200F
bakmanrayman [at] yahoo [dot] com fasterspider [at] gmail [dot] com
Joined: Oct 02, 2006 Posts: 1946 Location: New Britian, CT
Posted: Sat Mar 13, 2010 3:11 am Post subject:
I will be at Rhinebeck, and you can ask me questions about Hondas, that is if you can find me. But if you are looking for DOHC stuff I definitely will not have it with me. Best to check everything out starter, chargeing system etc on those bikes.
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I just don't really know what I should be hearing, and if I'm hearing things I shouldn't be.
