yayarx7

I need a carb badly. I will buy a YAW but need one right now so I was conemplateing another source. Can anyone tell me who, besides the god known as Paul, does a good job w/ nikki's.

Thanks

MIKE-P-28

iTrader: (1)

Please dont say knock off Yaw, he gets really upset over that. How bout getting a Holley replacement?

Maybe someone knows of a few things you can do for now, and then send an extra carb to him in the meantime?

theNeanderthol

iTrader: (1)

you could always rebuild your carb i hear you feel a huge difference between a 20 yr old nikki and a rebuilt nikki. I'm in the process of rebuilding my stock nikki im going to try some slight modifications I'll keep you updated on how it goes

kotkovetz

where do you get the nikki rebuild?

ladelberg

There is another thread to this affect today but I purchased mine from NAPA (I think the only parts I have ever purchased from those them).

yayarx7

I got the carb rebuilt by Rotary Perfromance in Garland, but they either failed to replace the accelerator pump diaphram or put a bad one in. It was leaking fuel like a facuet. Fixed the accel pump but still runs like crap. it was adjusted very poorly, and I have fiddled with the adjustments and have just made it worse. The thing will idle decent and accelerate well but at a cruise, like 12% load or so, it bucks and heaves like it's leaning out bad.

I consider myself an above average wrench but have horrible luck with carbs. The one nikki I rebuilt, was so bad I ran it for about 5 minutes and took it off. It dumped fuel at a enormous rate. black smoke and all. maybe I am just carb retarded!

I just need a carb for my daily driver, and connot wait around for a YAW so any ideas would be considered.

Thanks

MIKE-P-28

iTrader: (1)

Well I got 2 of them, both from 85's... They both worked perfectly, but the one I was using on my 85 had the idle adjusted way up cause of a somewhat bad front rotor...Thus the reason I bought another one used from mazdatrix, but when I installed it I had the same problem (loped really bad and stalled)... So then I knew it wasnt the carb. So now I have 2

PaulFitzwarryne

Mike P What are you going to do with your spare?

MIKE-P-28

iTrader: (1)

Since Im gonna go a 13bt, I dont think Im gonna need either. Actually forgot but I have 3. The other is an 83 carb, but I think there the same?

The 83 hasnt been ran in over 3 years tho.

Sterling

Between now and the time a replacement arrives, I would...

1- Check that the fuel jets have not been accidently switched on one or both bowls. (Smaller diameter in the primaries.)
2- Check that the linkage for the secondaries is not binding.
There should be light spring pressure holding the secondary shaft closed when you manually open the primary shaft all the way. Absolutely smooth action.
3- Check that the throttle cable is correctly adjusted by having someone put the pedal down all the way. The primaries butterfly valves should be exactly straight up and down.
4- Open the vacuum diaphragm box and check that the spring is installed correctly (not cocked); the diaphragm has no perforations in it, and that there is a good seal on the both the diaphragm gasket, and the gasket that goes between the box and the carb. A bad seal on either will render the unit useless for opening the secondaries.
5- Check that the fuel is in the center of the sight glasses on the bowls when the car is running. If one is not full, then the float is stuck somehow. If it is too full, then the float is'nt closing the needle valve.
If you should get to the point of taking the top off, while holding the top up-side-down, the floats should measure 9/16ths from the top of the float to the gasket when pushed closed.
6- Before tearing into the carb, you may have a simple vacuum leak. They are tricky because depending on where they are located, the problems they cause are often inconsistant - IE, anywheres from a crappy idle but fine at speed, to a fine idle and no power up a hill.

Remember, rebuilding a carb is easy once you've done it. So no matter how good a shop may be, they might very well have the least paid guy, or "the new kid" starting out there by rebuilding carbs. Not saying that kids or new guys can't do good work; just saying that they are untried employees. I could be all wrong about that scenerio, but it's plausable.

If they rebuilt the whole deally, then they rebuilt the accellerator pump. It comes with a rebuild kit, and they would have no use for it. Little time would've been saved by not installing it, so I doubt they neglected it. However, an inexperienced rebuilder may have messed up the adjustment when removing the cover by thinking it was necessary to remove the adjusting nut in order to disconnect the linkage. If that was the case, then you're pump will be all outta whack and you'll need to adjust it. But it would present itself as a terrible bog under hard accelleration, whether it is adjusted too lean, or too rich. (A real PITA to adjust..."trial and error in 1/4 turns of the nut!)

I suspect that the problems you're having are due to adjustment, a vacuum leak, or both. I would confidently rule out the carb rebuild as the culprit myself if I checked everything on this list first.

I would also spray lubricant on all the linkage - not forgetting the vacuum operation linkage.

Let us know how it goes.

RXcetera

Or you can ship it to me for a complete rebuild. My rates are 100$ for a rebuild, 150$ for rebuild/cleaning/polishing.

mar3

iTrader: (8)

Is that US or Canadian?

RXcetera

You crazy?? Those prices are American. With the exchange rate how it is now, 100$ Canadian is 62$ US. That's just wrong .

cpt_gloval

iTrader: (1)

how much experience do you have w/ rebuilding carbs? can you gaurantee that it'll be a quality rebuild? i need one of mine rebuilt, so i'd be interested in hitting you up.

jbontke

OK guys. The car runs pretty good under acceleration. It idles smooth when we figurered out the order of the adjustment screws. It will buck when cruzing under light throttle load. There is no need to go through the whole carb just because it has a fuel starvation problem under light throttle. Is there an adjustment for this? Do we need to change jets? I have tuned a rotary with a WOLF 3D and the actions of the car say it needs fuel under light load.

Does any of the electronics on the carb have anything to do with this?

I want to take the nikki off my 74 RX4 and try that but it was rebuilt by a shade tree mechanic and that might promote more problems. Good thing about it is that it has no electronics. Is this a better solution? I am also carbonetically challenged. The is no book in this whole wold that says "adjust this for more fuel under light load" or "if you have a hesitation that smooths out when floored do this". If I knew what to adjust this would be easy. I know the symptoms and the cure, just not the adjustment. PLEASE HELP!!

yayarx7

Well here's an update.

I found a huge vaccum leak in my homemade acv blockoff plate. Fixed it and am waiting for the gasket maker to dry so I can drive it and see if that was the culprit.

If that does not do it I am going to unplug all of the emissions stuff and put caps on every thing, just to see if it is a vaccum leak. It makes sense that it is. The idle speed idle air and accel pump are the only external adjustments. and they ahould not affect the cruise mixture.

I doubt that the internal, ie float bowl and fast idle linkage would have anything to do with the current problem.

wish me all the luck you can spare

yayarx7

YAYY

I fixed it. It was a vaccum leak.

Now the question is do I spend the dough on the yaw carb or that beat up GSL-SE.

If I buy another 1st gen I will have 5. God I NEED HELP!

RXcetera

Cpt_gloval, PM me .

Jbontke, carbs dont work the same way FI does. EVERYTHING is mechanical. If you find you're car works fine under acceleration and idles fine, but it hesitates under low load, chances are your primary ciruit is obstructed. Pull out all primary jets, clean them and blow out the primary circuits... that's the only way to do it.

jbontke

I wish carbs were easier to understand. I can tune the heck out of a rotart with fuel injection, but the carb haunts me. I will learn though. Or maybe I'll just jerk the carb off my rotary wagon and put the Wolf 3D on it....hummm...

RXcetera

Dont you dare .

jimmyv13

RXcetera,
Since you sound like you know RX carbs well, I need to ask you a question. Could my carb be all messed up since my 12A SP with full RB exhaust is slow as ****? Any comments from other members are welcome, too.

MIKE-P-28

iTrader: (1)

Maybe Jimmy, atomization of fuel is very important, and carbs are very sensitive to many outside variables. Are you sure your secondaries work etc?

jimmyv13

I can feel a pretty good kick at 4K RPM. Is that the only way to tell if they work?

RXcetera

First you'd have to define slow. But assuming it's too slow for the amount of mods you have, then you should definitely be looking closely at your carb. A 12A streetport with RB streetport exhaust and untuned stock Nikki carb should net you ~150hp. You could potentialy make much more power, but you're chocking off everything at the intake side. Basically, you're driving around with something akin to a firehose connected to a garden faucet... you're not gonna get much water out of that.

150hp is still very respectable for such a small car and is definitely not SLOW. 1/4 mile runs should be in the very low 15's maybe even high 14's.

There's most likely more than a few things wrong with your carburetor. First off, if you still have the stock jetting, you're running too lean. That might not really have much of an affect on power, but a really lean condition can lead to all sorts of engine damage. Before going too crazy with your driving (probably too late right?) I'd recomend a decent aftermarket carb, or at the very least, the biggest fuel jets and the smallest air jets you can get in that little Nikki. Having the proper jets will help your speed alot.

Other than that, I'd check for proper functioning of your secondaries (are they opening) and general proper fuel delivery from your accelerator pump and all other circuits. That Nikki accel pump is Waaaayyy too small for you setup too... at least try to get the biggest stroke you can get out of it, or better yet, add a spacer under it to increase it's capacity.

There's alot more that could be wrong, but without seeing your car, it's kinda hard to just guess at what's wrong. You are running lean, that's inevitable, but everything else is just speculation.

Hope this helps!

jimmyv13

15's or low 14's?!?!?! I get beat by 6cyl Stangs and Camaros. How freakin embarrassing is that? I'm quessing I'm still in the 17's.

When I ordered my exhaust from Mazdatrix, I asked them if I had to re-jet my carb for my ported motor and they said no...it'll be fine with what you got. I e-mailed RB, but never got a response, I'm not real impressed with them anyway.

What is the accel pump? How do I add the spacer?