Topic: help me trouble-shoot

[cyclezirk]

I have browsed the FAQ's and I am still scratching my head so I am taking the risk to post. 

Keeping in mind that I know as much about engines as I do about women, you'll have to start at the basics...and maybe type your reply real slow.

Trying to get my 73 cb750 running well enough to use as a commuter.  First off cylinder #1 is not firing (the pipe is cold) and oil sometimes leaks out the #1 exhaust (yes I did change all the plugs, they were all black).  Also, when I ride sometimes I have lots of power and sometimes it feels like I am trying to start out in 5th gear up hill, she just can't push herself forward.  What is wrong?

I plan to get a tune-up kit and change the points, the plugs, the plug caps and maybe wires; I also have a relining kit for the tank, although it is not that bad, I just don't want to start my long educational process on carbs before I know that junk from the tank isn't getting in.

Any suggestions or ideas??

[Lumbee]

...sounds like u'r on the right track.  I'd bet the reason #1 is not firing is because of a blocked jet.  If you havn't torn into the carbs yet now is the time.  I'd also by a compression gauge and check all cylinders out.  You should have 100 psi or better in each cylinder.

[mk0094@hotmail.com]

hey. first, did you put an aftermarket exhaust or air box on it? i found that changing my exhaust on my old 500 f caused 2 cylenders to be rich (black and fouled plugs) and i had to rejet the carbs, and possibly sync the carbs. it might sound like some work, but it mad a ton of difference.

mike

[fhoffman]

Sorry, time to take the carbs apart.
Get yourself 4 carb repair kits (available at various vendors online), from them you will at least need the float bowl gaskets, and likely the needle valves.  Read your service manual thoroughly before you start taking the things apart... try to understand how the various jets and nozzles interact.  Keep the pieces from each carb separate so they go back where they came from and don't get mixed up.  Make notes in your manual when you see it dosn't explain something well, so you remember how the parts re-install.  Take your time... do it on a bad weather day sitting comfortably at a table with good light, and good music.
It need not be a pain.
/Frank

[cyclezirk]

Thank you all very much.  Time to order some parts and get to work.  When you order a carb kit, does the beer come with it?

[cyclezirk]

So here is my list in order:
1. compression test
2. tighten cylinder head bolts
3. cam chain adjustment
4. valve clearance adjustment
5. spark plugs, caps, and wires
6. condenser (capacitor)
7. breaker points
8. ignition timing
9. air cleaner
10. oil change
11. carbs kits and sync

anything else?

[BobbyR]

There is one other thing you may want to do. I was noticing my bike suffering a loss of power for a split second after shifting I ignored it. Once day she suffered a real loss of power and then it would return. I was riding it home when I had almost no power but every thing felt like 5th gear on a hill. I found out my primary wire had chafed and was shorting out my points on cyl 1 & 4. The wire is routed too close to too many sharp objects.l This is something everyone should look at from time to time.

[cb650]

If it has been sitting for very long clean out the tank.



             Terry

[byidesign]

Do check obvious things first, like check for old or contaminated fuel.
  drain the carb bowls into a glass container ,and have a look see, do the same,
    with the tank. run a small hose from the petcock {on res} if it is anything other,
     than {gasoline color }. it's time to do a good cleaning.
       water in the carbs, will cause a lot of strange things.....