Carb Issues

Hey all, I have been reading for a while and done a lot of searches about my problem. I have a 65 cj-5 with an f head and and carter yf carb. I rebuilt the carb, put new plugs, wires, points, condenser in and it still isnt happy. Reving it, it sounds great. When idling its rough but not missing. It repeatedly surges and wont stabilize on a constant rpm. I drove it some yesterday and it surged while driving it when my foot wasnt on the pedal. I havent adjusted the float level with a guage which I will do this afternoon, but just by eyeballing it the float looks fine. The timing is right. Other than the float level im at a loss. Any suggestion will be appreciated

 

I agree! However, I have beat my brain and 2 cans of carb cleaner trying to find one. With that said I will continue my search tonight, lol.

 

Have you rebuilt the carb? If you are new to this Jeep, and the rebuild hasn't been done recently, it's kind of inevitable that you will rebuild it. Either that or you'll replace it with a Solex.

I would not hesitate to take the carb off and take it apart to clean it with spray-on carb cleaner. Taking the carb top off is something you should be prepared to do in the field anyway, so it's better to do it now than later.

IIRC (from what I recall reading) the best carb kit comes from "The Carb Shop", and is the only kit that properly seals the lifter link. You may have trouble getting "the dip" depending on where you live. Also, total-immersion-type carb cleaner has been made more environmentally friendly and less effective over the past decade or so, so it may take a while and/or require some mechanical persuasion to get everything in or on the carb clean.

The YF has been used on a lot of vehicles, and is known to be simple and reliable. However, I don't expect it will ever run right if it's full of gunk or gummed up. The Solex is popular (again from what I've read) because it's a bolt-on replacement, and any carb could be worn out after 50 years of service.

 

I have rebuilt the carb 2 days ago. I guess it is possible that I need to buy a new one or have mine refurbed. I am reluctant to buy a Solex because I want to stay as stock as possible. Plus Im kinda hard headed in the belief that if someone else can make their cater run well so can I. I have done a lot of carb tuning in the past on several diff carbs, making adapter plates rebuilding old carbs and making them run on something it wasnt intended to run on. Im not saying Im a master carb guy buy any means but Im not scarred of them either. This problem just has me stumped.

 

im dealing with the stock, rebuilt by me carb, on a stock engine, and I already used the correct rebuild kit. Srry if my las post was confusing

 

Now there is a piece of info that is very usefull. I was already thinking about swapping the old needle and seat back into the carb to see if it helped. The pump and gaskets were the stuff that was mainly worn anyway. I will try this and hopefuly it will work but if not I will prolly end up buying another rebuild kit.

 

OK, Im slowly getting there. After trying several thigs I have determined that just about every possible place that I could have a vacuum leak is leaking to an extent. So, now I am in the process of disconnecting every fitting, cleaning, new teflon tape, and retightening. And slowly with every fitting it runs better. I still have 2 more to go and hope it will be fixed when I get to them in the morning

 

The correct needle and seat assembly for the F-Head should have a spring loaded needle and a small pin that rides on the float tang. The the diameter of the seat orfice should be .076.

Worn out carters can be made to run well again with a little patience, An excessively loose throttle shaft can cause the idle to be erratic and hard to adjust but they can be shimmed snug again using brass shim stock with good to excellent results.

While you have the carb apart take a good look at the tiny orfice in the bottom of the Idle/Low Speed jet tube, Make sure no small particles are stuck in it and that it is not damaged or crimped partially shut with sidecutters.

Something else that can cause erratic idling is a broken or missing spring on the distributor mechanical advance fly weights, Its rare that it happens but its easy to check and worth eliminating before getting to far into other things.

General question, Was it doing this before you rebuilt the carb?

Let us know how it runs after you get the vacuum leaks sealed.

 

before the rebuild it was missing on a cpl cylinders, had no power and didnt want to rev up. Its running much better than it was. The pump in the carb was terrible, I dont know how it ran at all. The throttle shafts are good and as much cleaning as I have done I hope all is clean but I will double check, thx

 

Fixed It!!!!!!, I took it all back apart and compared old parts to new parts. Well guess what? The low idle jet was completely different. So I cleaned the old one up and in it went. Put everything back together and she fired up and ran perfect. Thx to everyone who tried to help.

 

Glad to hear it I dont know exactly what model YF Carb you have but for use on the 134 F-Head based on 938 SD Model Specs the Standard Idle/Low speed jet tube orfice diameter should be .028.

I also purchased a kit that had a new Idle/Low Speed Jet and it was way to small.

 

It pays to save your old pieces.