Topic: stalls with some throttle

[setdog]

75 cb750 k5

Basically stock, exhaust is 2 into 1. I'm told might be jardine.

Set the timing, adjusted valves, to spec (I'm noob but its as best I can achieve and I believe
Its all within acceptable limits), cleaned carbs and replaced all but needle jets to. 

Bike starts with choke on, revs high, I can buzz the throttle a few times, but it likes
To shut off if I turn choke off and hit the throttle.  Manifold boots are old, but tightened with
Worm clamps,

I believe my problem lies in the fuel / carb system.  Possibly too  too much air, either through manfild boots or air filter boots.

I'm struggling to get it to hold idle and not stall with a blip on the throttle.  Basically wondering
If I'm on right path here by focusing on carbs. 

[goldarrow]

Check to make sure your throttle cables are not binding, also check for air leak by car intake

[bjbuchanan]

What is a "blip" of the throttle? A quick like goosing of the throttle like sport bike style doesn't work on that bike because you don't have accel pumps. It stumbles and if it isn't all tip top it probably dies.

Just a good pull of the throttle shouldn't make it die tho. Spray carb cleaner around your boots systematically, don't just hose them down. If you have leaks it will cause some problems

[setdog]

Blip meant to goose it, its pretty strong throttle on its own, and have been doing this,
Feels more natural I suppose, I'll observe this.

misreading carb problems led me to teardown a twin, only to end up back on carbs.

[ekpent]

For starters touch a wet rag to all the header pipes and compare the sizzle to see if its hitting on all four approx the same.They will run on two or three but very unhappily.

[greenjeans]

Check to see that you are getting a good spark to all 4 cylinders.

If there is one thing that I've learned about these beauties over the years, it is:  the carbs just can't be clean enough.   
Also, after all is said and done, you should balance/synch the carbs when you get it running better.   If you take your time, you can bench synch them close enough to get things rolling.

As much of a pain as it sounds, I'd take the rack off make sure all of your jets/holes etc are clean and clear.  Take time to set the floats properly.
Check the actual fuel level with the clear tube method.   

If you are running a stock airbox (definitley makes things easier), what shape are your airbox rubbers in ?  Those are relatively cheap ($40 for all) and can easily be had.    I'd grab 4 new spark plugs too (cheap) while you're at it.  Plugs can look clean and still foul.

The manifold rubbers can be pretty old and hard and still keep a good seal.

Never hurts to recheck your timing and valves - doesn't take long, and you'll find that it will familiarize yourself with the process and become much easier
and quicker to do.    Also - don't forget the cam chain tensioner.

You're on the right track - take 1 thing at a time and eliminate it as your problem.

Has the bike been sitting for a while ?      I find that they always start to run better after the engine has gotten warm and ran a few times and burned off all the varnish etc from sitting - the rings start to loosen up after a few good rides.

[iron_worker]

A properly adjusted bank of non-PD carbs (no accel pump) should be able to rev cleanly with a quick twist of up to half of the full throttle travel. They way they achieve this is by running over rich pilot circuits to act as a crude accelerator pump that is always on.

IW

[setdog]

Just did some fiddling, here's what I found.
 Definitely a clogged up petcock, flows well on reserve only.
Explains a lot, and before you comment, it won't get cleaned until tomrw.

But if you're up to it, it started easily, it even performed what you call an idle.
But choke fully closed.  Open the choke or pull the throttle slightly and rpms notched up significantly, close the choke and rpms dropped.  Air screws set at 1 turn, and then 1.5,
Even went above and below those turns but only got similar results.

Light at the end of tunnel...It was kinda running.

So, if petcock valve is clogged...start here?
Then probably another carb bath.
And a good tank cleaning, (probably best place to start?) I'll have to look into a seal, haven't
Researched or ever done this, how is this stuff por15?

[Duke McDukiedook]

If your petcock is clogged odds are your tank is bunged and must be cleaned first before you do anything else.
If you don't take care of that first everything else will just get clogged up again.

[setdog]

I deserve a smack.
Why wont she run?
Not getting gas....