2stroke1971

So these are notorious for hard starting. Heres what ours is doing.
We've had it for a few weeks.

When cold, it wont start with choke, we have to fire it up with choke off, at which point it seems like its running on one rotor, or part of one...pop pop pop pop pop....wont rev, if you try it woofs out. If pull the choke at this point, it dies.

After this goes on for a few moments, you can pull the choke and then the RPMs go up and then it will rev ok. After the choke goes off, the RPMs drop down and everything is fine. I rebuilt the carb, and LOTS of things improved, but not the weird starting.

Today was the first time I ran it after the carb rebuild and it took a long time to start up so I shot some starting fluid into it and it fired right up....then it went into it's "running on one rotor" phase, so just for laughs, I shot some more fluid into it and it smoothed out NICE momentarily.
Anyway my point is this....what would that be a sign of? Not enough fuel when cold? What would I do to correct that? I dunno just thought these symptoms might scream something to someone!

Thanks,
Neil

Rotor_Venom08

iTrader: (3)

i can tell you that your timing is probably way off.

or your not getting goo spark, either from a bad coil or ignitor maybe.

and are you sure your getting good fuel at the carb? and that your pump is working properly. i know the filter or the strainer in the pickup could be clogged and allow the car to idle then die when giving it gas.

2stroke1971

Thanks for the reply!

The timing thing makes sense and I will tell you why...the previous owner did alot of stuff to make up for how crappy it was running when he finally sold it. It had that flame out right off idle thing happening and he put a new cap and wires, etc on it and it didnt go away. (a rebuild of the carb took care of that, thats why I did it)

He told us that failing all else, he adjusted the timing and the mix screw until it ran "just well enough to have fun with" so he said. Looking at the distributor, it is ALL the way one way at the end of it's slot. I will have to look up how to check the timing, I have a timing light.
Previous owner had replaces one of the ignitors with a junk yard part but who knows.

Can you tell me about the mix screw...is it an air screw or a fuel screw on the Nikki?

I am having a blast with this thing, (it belongs to my son- it is his first car)....I really have to get one myself. As soon as I finish working on it I wont have any more excuses for a "test drive"!

2stroke1971

It occured to me what he said exactly....when he set the timing and mix screw to spec, it would not run right, so he fiddled around until it ran well enough to drive it....

that was the condition we bought it in, you could drive it, if you got through the starting, and then feathered and pumped the hell out of the pedal to get past that dead spot off idle. VERY hard for my son to learn the clutch with that symptom! So, the dead spot is gone, I will have to check and set the timing and see what it does.

Rats nest is still bothering me. This is my confusion...lets take the high altitude compensator. Lets say I plate it off and plug the vacuum connectors. THen I drive to Boulder Colorado. Will it run poorly there, or will it just make dirtier emissions?

Thats what Im not clear on, are any of the rats nest items engine management, that is to say, making the car run BETTER given changing conditions, or is it ALL for the sake of keeping the emissions clean as possible given different conditions.......

If the Rats nest is all gone, do these things still run ok, or will it be some weird crap like it only idles well if its above 50 degrees or something like that?

apsolus

iTrader: (2)

If u spray then it runs fine id say you got a fuel delivery issue. Might need to pull the carb again.

2stroke1971

The pump is pumping fine... once it runs a few moments with the one rotor sounding thing, I pull the choke and it smooths out, warms up, and then idles down just fine and runs like a bat out of hell. What the starter fluid did is in that very first two minutes, when its running very poorly, it would smooth right out.... so if it is a delivery problem than it goes away after two minutes...and it has no problem breaking the tires loose or blowing down the freeway.

Things only got better after the carb rebuild, the weird start thing was there before the carb rebuild. I think if I was having fuel delivery issues, the symptoms wouldnt go away after the first two minutes??? I dunno. I will see if I can get to the timing check this weekend.

Rotor_Venom08

iTrader: (3)

well its going to sound like crap when its cold if you dont have the choke open to let it warm up. you have to start it with the choke open and it will fire right away. then give it a few minutes. im sure you must have driven a car with a choke before being "experianced" lets say lol so im sure im preaching to the choir here. just saying. starting it then pulling it will cause it to fall on its face.

unless you mean even when its not cold you have to pull it.

check the timing defiantly. if its just really hard to start or misses or pops. its probably way off as i said, and id check the entire ignition system for corrosion and wear. 30 year old parts are just that.

major rotor

My weed eater did the same thing. My fuel lines where stopped up. Check that.

2stroke1971

Yep, I had alot of old Mopars in the day with hand chokes. in any case, when cold, it wouldnt start at all with the choke pulled at first...its like you HAD to fire it up w/o choke for a minute, and then pull it.

Its a bit different now though...ive got some idle issues....at this point, starting is a bit weird but tolerable, but after is warms up it idled down too low and got crappy....I adjusted the idle stop or what I think is the idle stop...that cylinder towards the firewall with the plastic dampening tip on it....then it idled too high, except if I pressed it against that plastic tip then it was too low again,but almost right.... its like its not returning all the way to that tip on its own. Tomorrow I will spray the shaft down with some kroil and maybe put a stronger spring on it.
Still havent dug out the timing light!
I think I will make another post about what its doing now.

Thanks everyone for your input so far.
Neil

Rotor_Venom08

iTrader: (3)

goto harbor freight there literally 12 bucks. check the timing. you shouldn't have to adjust anything to far if it was previously running at some time. once the timing is right adjust the screws.

the idle mixture is the on the bottom right under the fuel lines and the idle speed, is the one on the right under the linkage i believe. get the car nice and warm before you adjust anything.

you sure there arent any vacuum leaks?

should idle stock around 750-800. i like mine around between 800-1000. but thats just me and with the secondaries wired i think it helps with bogging from take off.

Rotor_Venom08

iTrader: (3)

forgive me again... as im sure you are well aware and dont need some 20 year old kid telling you how any of this works... but are you letting the choke shut itself? or are you closing it? you have to let it get to operating temperature. which is about between the first line on the left and the second. i usually let it in slowly in increments, from 3k-2k-1.5k then i pull off with it in and it warms up by the time i hit the first corner. just a thought. it shouldnt be that hard to start...

what about the fuel? is the filter clogged? the fuel orange? you getting good spark all around?

2stroke1971

Ive been wrenching on all sorts of weird crap for years, but I am new to this type of motor, so I will take any advice you can give me!
You know, the first test drive we took, we ran to the 7 eleven and back, it was about 3 miles up and 3 miles back. only when we got home did the choke let go. That seems like a long time to me. As far as the temp gauge, I dont know, it is intermittant, and most of the time doesnt work at all.
If I pull the choke all the way it revs HIGH. About half way does well, and then at some point, it turns itself off. Any time I tried to turn it back off manually, it idled down too low, but then again, thats my problem at the moment, once warm it idles down. I will try to idle it up later today.
Also my secondaries stopped working after the rebuild. The linkage is hooked, and I can make them go off by pushing on the linkage.....
Neil

Rotor_Venom08

iTrader: (3)

theres an electrical connector on the carb that disengages the choke once it reaches OT. its on the drivers side and is white. and two prongs i think.

honestly it sounds vacuum related. what all did you do to the car? just rebuilt the carb the more info we have to go on the better. spray some starting fluid around the carb base and see if the car idles up, and trace down the leak. if your getting it to start and run with the choke then its sounds fine.

but like i said without the timing for sure set properly , and htat there arent any vacuum leaks. because you can adjust the screws all day and it wont be right, so id defiantly start there