Topic: Hard starting, seems worse when choke is on???

[Lumbee]

Lately my 78 750F is hard to start.  If the choke is off it will putt-putt-putt like it wants to start, but then when I pull the choke it will "putt" once, then nothing until I close the choke again.  I have to go back and forth like this for a few minutes before it will start.  Any ideas?

[scondon]

Things that come to mind:

low battery(weak spark)

restricted airflow(filter,airbox opening)

clogged slow jet(one or more cylinder does not get enough gas to fire properly).

 How is it running once you get past the starting issue?

[Lumbee]

...runs like a champ once it gets started.  Weak battery could be a factor, due to running the battery down trying to get it started...finally got it started with the kicker.  Chould the choke be flooding the cylinders when I pull it?

[dusterdude]

it could,but i think it would have to be rich to begin with to do that.of course it all depends on how long you crank on it before it starts.i do hope this isnt the chop,hate to see you miss mb.

[Lumbee]

...it does it from the first kick...

...naw, this is the stocker not the chop...

[dusterdude]

cool,man it seems like that sucker is way rich.

[scondon]

   When you say that this has been happening "lately" I'm under the assumption that this is a new development and your bike has been starting with no problems in previous months. The weak spark, restricted air, and clogged slow jet are some of the things that can develop over time and cause hard starting. Another is points wear which can cause the gaps to change and throw your timing off at idle ("F" timing mark). Sometimes a combination of the above.

  I've had good success with starting "hard to start" bikes using the following method. With ignition on and run switch in "off" position, apply choke, hold throttle open and kick lever 2-3 times. Then turn run switch to "On" position and kick start.  This primes the carbs and cylinders with gas for an easy start, especially if one or more slow jet is partially obstructed. Using the kickstart(instead of starter motor) leaves more power for the plugs if battery source is week. I've got no scientific data to back any of this up, just observations I've made over time

[Lumbee]

...well this has been a on/off problem since I've had the bike.  I'll have periods of easy starts that last anywhere from a few weeks, to a few months.  Then i change something, and it will crop back up.  However I can never tie it to any specific action.  For instance I have another bike I was trouble shooting, so in the past week, I pull the carbs off the 78F, and put on the 77F for a trial run.  I also pulled the points and advancer off to try on the 77F.  I might have answered my own question here.  I'm not sure, but I think I have the advancer from the 77F on the 78 now.  And now that I think more about it, at one point the 77 was hard to start, much like the 78 is now.  Could a bum advancer cause this behavior?

[scondon]

I wouldn't think the advancer would affect start-up. A bum advancer would cause the bike to "bog" on acceleration.

  I've got three 77-78 F's(two running) and have swapped all kinds of parts back and forth for trouble shooting so welcome to the fun   The constant trouble I've had with these models is keeping the pressed in slow jets clean and clear. I think once they start getting that chalky white aluminum build up (usually from sitting unused for prolonged period of time) that they are beyond help from "casual cleaning"(even carb dip).

  Low compression will make starting difficult and these bikes(77-78 F) are known for. I seem to recall you had 120 on all 4 so nevermind.

[dusterdude]

it might if its stuck on full advance,a cold bike is a #$%* to start on full advance.i can tell ya that from personal experience