Stumped: hot start = huge cloud of smoke
 

Ok, apparently I should have never attempted this carb swap :) I apparently got way in over my head.

The car used to never have an issue at all with starting when hot. Cold start was a different story though. But with the old carb, it would never smoke, hot or cold.

Now it seems everything has totally reversed with this new carb (still nikki, supposedly bored venturis, I don't know enough about carbs to verify). Cold start is just turn the key. But now she smokes at start (blue, so oil) for probably 30 seconds or so.

But if I go drive it for a bit, shut it down, leave if for more than like a minute or 2, she does not want to start again. Playing with the throttle can get it started, but it looks like the ATF treatment almost. It's pretty ridiculous. It smells pretty much like gasoline and has a tendency to be much more white in color. We yanked the plugs and they looked ok, not spectacular, but ok. They are only a few thousand miles old.

So I basically have no idea where to go from here at the moment. What in a carb swap could have caused the smoking? The emissions equipment did go too. At this point I'm almost tempted to go back to my old carb which just dies when the car goes around a corner. :( That or give up and find a GSL-SE.

Thanks

I wish someone would write a good page for "how to tune your nikki carb if you are a total moron"... don't feel bad, I am in your shoes when it comes to this... i have no idea how a carb works, and stuff like that...

I am thinking about going to a pick and pull, finding an old carb, taking it home, spending about 3 weeks cleaning it and replacing stuff on it that looks bad... and then trying it...

Once I take the damn thing off and take it apart, I will figure the bitch out... hehe

If you find someone who wrote that book, I want a copy :)

I'm currently using my 3rd carb as a kinda learning tool exactly like you are saying. Unfortunately, some things are missing off of it and all 3 carbs are different models (not to mention modified differently). So it's not always entirely helpful. Although I did notice a mod to it that may actually stop the problem I was having with the stock carb, so I may transfer that, then swap them back if I can't get this new one running. But the new one is so much smoother :)

I am guessing it has somthing to do with your OMP..... I guess that the vacume, is sucking in oil through the OMP, when you turn it off........... Thats the best bet.... I hope I have been of any help:p:

Trust me, it's not the oil metering pump. :D Besides, he said it looks (white smoke) and smells like gasoline.

It sounds like your carb is flooding on hot shut-down. Try checking the float level. It should be in the middle of the sight glass.

re read, he said BLUE, and said OIL....:p:


EDIT: and white, and gas......


MAKE UP YOUR MIND MAN!!!!

How's the idle?
How's it feel in comparison to the other carb?
Have you looked down the carb while it's running?
How about when you shut it off?
Are you regulating the fuel pressure?

Re: Stumped: hot start = huge cloud of smoke
 

I think you need to re-read. :D

The blue smoke on cold start-up is pretty normal on older engines because of wear on the oil control o-rings. Nothing to worry about.

when you replaced the carb, you didn't happen to take the intake man. off, did you?

OMP???

Not possible.

OMP = Oil Metering Pump .... it injects a little bit (like .7 ml per minute) of oil into your carb to lube the apex seals. Many people ditch the OMP, and run mix gas like a 2-stroke... lots of fun when you bog the car down on the highway in 5th, then downshift to 4th and watch the huge cloud of blue smoke blow out... :D

Jeff

Well, I've started something fun here :)

Idle is crap below about 1200 rpm, but I was told it would be due to the bored out venturis. It doesn't idle worth a damn when it is cold though. It's trying to sound like a large V8 or something :) Once it is warm though, it does idle smooth, but high.

In general, the carb itself runs much smoother while driving with more power, a smooth transition to the secondaries (old one was not smooth at all) and runs strong to the redline. Seems like it pulls better throughout the whole rpm range, and doesn't hesitate sometimes at stops (everything about this new carb is far superior except the hot start :))

Haven't really looked into the carb when it is running or after I have shut it down. Anything I should really be looking for specifically? Or just too much gas. The fuel level is right about mid way on the sight glass.

I have a fuel pressure regulator on there, but it is one of those dial crap ones (Profuel or something stamped on it). It's set at "2-1/2". What the units are on that is anyone's guess, since I'd imagine the output psi would depend on the input psi. I have a holley regulator here but we haven't gotten around to getting it in because at the same time I'm doing that, I'm also putting a permanent fuel pressure gauge in the car. So we are still monkeying with that. The carb became the main concern though currently.

No, didn't take the intake manifold off.

Ok, worth a try :)

Jeff

i'm having this kind of problem too. I set my regulator at 4 psi and it hot starts every time. i'm wondering if my pump is bad though. put some regular old oil in it (down the intake) and lube it up good and set your fuel pressure higher and see if that helps.

can someone take a pic of the sight glass for me as I have no clue what you are referring to.

And, is that container on the left side of the carb a hot-start-assist thingy, or is that a cold-start-assist doohickey?

and last Q, by adding a little 2 stroke oil to the gas (1:125), can you completly remove the OMP and all related parts?

cheers'

The sight glass is the little window in the side of the carb that allows you to see the fuel level in the float bowl. There are two on the Nikki carby, one for each of the float bowls.

I'd say the container you're refering to is some sort of sub-zero starting assist. There is also a hot start assist which is located on the lefthand fender. It's basically just a little motor that pulls the throttle open when you crank the motor. Most people get rid of it.

And yes, if you run 2-stroke in the gas tank you can throw away the OMP and all related junk but you must fabricate a block off plate. I made mine out of aluminium.

Hmm, up the fuel pressure? I would have assumed the other way, but then again, I'm a moron about carbs :) Worth a shot for sure though.

I don't see how upping the fuel pressure is going to help if your carb's flooding.

I don't either :) I'd think it'd be the opposite. Maybe drop it? Maybe kick the carb in the head a few times?