Topic: Cold Starting Mystery

[BobbyR]

I refreshed the bike over the Winter. Rebuilt the carbs and believe I gave them a good cleaning. As a back up last week, I actually ran a can of Seafoam through the at mixtures up to almost 100% (man I stunk up the block) Here are the symptoms which have improved:

Cold Start requires repeatedly twisting the throttle while on the starter button.
When she does catch, repeated twisting is needed to keep it running, at some point I can hold it to 3K rpm.
When she is really warmed up, all is normal. The bike is really quick and good throttle response. dies very smooth.
When she is full warm, one quick tap of the starter and it fires right up.
Timing is dead on, point gap perfect and i have a nice blue spark on all plugs.
The choke butterflies close fully, and fast idle on choke cam is adjusted.

I am thinking plugged slow jets. I am not sure the float heights are correct, can low or high floats cause poor clod starting but normal warm operation?

[nteek754]

first of all what is the bike? all and Ive had a few got two now of the 76 and down 750s when I go to start them it has allways been full choke full throttle and of coarse back right off the  gas when she fires but this has worked for me for 32 years I did it just the other mornig with my 73 ONE KICK and boom she was purring  now if your  into the 77 78 carbs  sorry  no I have acouple of them two  one  the carbs were taken off and acid dunked cleaned  sinced and new intake boots  and it starts like the others in my collection check for leaks in the boots accilerater pump may not be workin till it gets warmed from the engine heat  hope this helps  seven fifty four ever

[BobbyR]

I am sorry, it is a 78 750K. I bought new boots which made me decide to clean and rebuild the carbs. The bike used to start after one quick stall and then she was good to go. I hunted down all leaks in the manifold boots and airbox. That is why I am up a tree on this.

[bowhunter]

Sounds like the slow jets are clogged. The 78 has an accellerator pump built in, that's why tweaking the throttle when cold keeps her running. You need to tear down the carbs, including the slow jets, and do a proper cleaning job. Seafoam only works if there is at least a little fuel getting through. Sounds like yours are mostly clogged. The slow jets areremovable, a twist and pull with a pair of pliers will get them out.
Have fun! If your first attempt doesn't work, do it again untill it does! Mine took 4 attempts before it ran right!

Bowhunter

[BobbyR]

Bow, I do believe you are right. The bike runs so good when warmed up I forgot how good she could run. Well I guess you figure it is not float level, but I will check that when I pull the carbs off again. Thanks Bro.

Bobby