Topic: Won't start with out starting fluid?

[schwebel]

I have a 73 Cb350f that I have been tinkering with and the bugger won't start without starting fluid. It starts and runs first kick with the fluid, but when I kill it it won't start back up without it. Even right away. The starter is shot, but kick works fine. I know it's running a tad lean in the midrange and am going to raise the needles a notch. I have been having a little trouble getting it to idle right. Recentley I kremed the tank, new fuel lines, fuel filter, cleaned the carbs, set the timing (new points/condenser), and adjusted the valves. I am going to sync the carbs this week. I am boggled and don't know what it could be.

This is the first time I have had this bike running as it was a garage find, any ideas suggestions?

[my78k]

First guess is it is still the slow jets. They are so hard to get really clean. Perhaps the vacuum created once started is actually drawing some in from the main jets but once it is dead the idle jets being plugged won't allow enough vapour.

Is it running on or off of choke?

Dennis

[schwebel]

It's runs best with about 1/4 of choke. With it off it stumbles around 4-5k, so I figure the needles need raised (maybe). I have the air screws set to .75 turns (factory spec) The plugs are a little white and the idle is a little erratic and "sticky" The mains are new, but the slows are original.

I didn''t think about the slows, guess the carbs are comming off tomorrow...lol.

[fang]

Do a compression test.  You might have none.
-steve

[schwebel]

I've never done a compression test before. I think my brother has a guage? How do I do it on a bike?

[750goes]

check your fuel filter, for any evidence of KREEM, or other rubbish in it...drop the bowls to make sure you have clean fuel coming through - then clean the carbs if need be if not already done..

good luck

[1timduke]

+1 on the slow jets, are you running a stock setup or does it have pods or missing airbox components?   Stock exhaust?   This will change the factory recommendation and most likely cause the lean condition.   Vac sync will improve idle a great deal.   Compression test (+1, again) will give you a good idea of the internal condition of the motor.   Also try 4 new plugs.   If you have a partially blocked fuel line (+1 again), it can cause stumbling at higher RPMs as need for fuel increases.

Step #1 this is easiest w/ an electric start, but I guess it could be done w/ a kickstart.
Remove all the spark plugs.
The compression gauge has a fitting that threads into the spark plug hole.   
Turn off the fuel and drain carbs.
Turn the motor over for a couple seconds or a few kicks.
Record the immediate result and any subsequent drop in the gauge.
Compare results to the manual specs.
If you get lower PSI or dropping pressure, add a few drops of oil to the cylinder, repeat he test, if PSI increases, you have worn rings, no change with PSI out of spec, then you have worn valves.

This is my version, there's probably a step or two I forgot, but it's a start.

-Tim

[schwebel]

It does have new plugs. The exhaust has the stock pipes, but I have CB500 aftermarket mufflers on it, 2 into 1's on each side. They might be a little higher flowing?, but they still have the baffles in them. The airbox is stock and have a brand new facorty filter. I have new clamps for the carb boots, and have checked it for leaks between the carb and intake.

As far as the fuel goes, I let the tank cure for a week after kreming it. I also ran gas through the tank into a filter to another gas can to get the boogers that might have accumilated in the tank before I put any gas into the carbs. I ran it through till it was 100% clear.

If the compression is bad, can you use anything to fix it? Don't they make something for cars you can add to the oil? Also does anyone know the compression specs for a 73 CB350f?