Carbi Problem?

[Jeff0308]

I finally got my bike going yesterday but have a problem I am not certain about. The FJ has been sitting for about a year but in that time its had the tank off and Tank Kreme put in. I put it back together with new fuel , Fired it up and what appears to be running on 3 cylinders. Feeling annoyed I pulled the Carbis off and ran some carbi cleaner through it. It seemed to fix the prob ...... Well what I thought it had until I started it again a month later and the same miss fire.. This time I got the Pilot Jets cleaned out and again the same prob. Even gave them a light blast with compressed air. Anyway. Its starts on choke ok, Runs quite smooth until the choke is off then starts kicking around with the hint of a mild popping as if its lean. When it warms up it smooths out a bit, but still has a mild miss. Any suggestions? I thought the carbs may be out of sync? My other question is even though the carbi bowls dont appear to leak do the gaskets need replacing and would this cause any issues. Cant smell any fuel only from the tank cap mildly. Regards Jeff

[RichBaker]

The drilled passages in the carb bodies, and in the float bowl get clogged like the pilot jets, and need to be blown out with compressed air. Just cleaning the jets is 1/2 the job.

[Pat Conlon]

What we have learned about cleaning the carbs can be summarized thusly: Half measures avail us nothing.

[movenon]

What we have learned about cleaning the carbs can be summarized thusly: Half measures avail us nothing.

How true. Soon working on carburetor's will be a lost art form along with making wooden wagon wheels and rebabbiting (the word isn't even in the spell check)  bearings... 
George

[ribbert]

Jeff, the bowl gaskets should be fine unless you have actually damaged one. I would make sure the carbs are somewhere near synced to eliminate that.
If the tank is clean you shouldn't be getting recurring blockages.

Remember, with our fuel, we don't have all the carb issues they have in the States. With a good filter and clean carbies to start with they are pretty much a set and forget item here, even with long periods of storage.

I pulled mine apart for the first time ever at 100,000 km's and nearly 20 years to re-jet them and they were spotless, which was not surprising.

Noel

[Mattman]

Sounds to me like the pilot circuits is needing cleaning. There is an art to cleaning them though!

I finally got my bike going yesterday but have a problem I am not certain about. The FJ has been sitting for about a year but in that time its had the tank off and Tank Kreme put in. I put it back together with new fuel , Fired it up and what appears to be running on 3 cylinders. Feeling annoyed I pulled the Carbis off and ran some carbi cleaner through it. It seemed to fix the prob ...... Well what I thought it had until I started it again a month later and the same miss fire.. This time I got the Pilot Jets cleaned out and again the same prob. Even gave them a light blast with compressed air. Anyway. Its starts on choke ok, Runs quite smooth until the choke is off then starts kicking around with the hint of a mild popping as if its lean. When it warms up it smooths out a bit, but still has a mild miss. Any suggestions? I thought the carbs may be out of sync? My other question is even though the carbi bowls dont appear to leak do the gaskets need replacing and would this cause any issues. Cant smell any fuel only from the tank cap mildly. Regards Jeff

[ribbert]

How true. Soon working on carburetor's will be a lost art form along with making wooden wagon wheels and rebabbiting (the word isn't even in the spell check)  bearings... 
George

George, most real mechanics skills are gone now, unless you can still find an older mechanic. They have become parts replacers with poor to no diagnostic skills.

Noel

[Jeff0308]

I pulled the carbis off. Cleaned oiut the pilot jets, and the carbis. Put it back together. Same result. I even got the bike shop to do the Pilot jets after I did it, Again same result. The main jets have been cleaned as well. I am wondering if its a sync isue. I was going to pull them apart again and check again but sometimes you just are over it, so I am going to let another  bike shop have a go I think. Its really pissing me off. I absolutely hate people working on my cars/ bikes other than me. I get so frustrated and annoyed if I cant do it myself. The people who did the club permit thought it was an old fuel issue, so what did they do? emptied the tank and filled it ALL the way to the top with new fuel. At some point they must not have heard me  when I said that the fuel is only a week or 2 old. It  Was in the to hard basket for them and they are a bike shop. So Noel I do agree with you, nobody knows how to fix old things and very few people have mechanical knowledge of pre fuel injection era. Now its throw it and replace it. That shits me bigtime.

[FJ_Hooligan]

Did you pull the idle mixture screws out and spray through that passage?

[movenon]

I pulled the carbis off. Cleaned oiut the pilot jets, and the carbis. Put it back together. Same result. I even got the bike shop to do the Pilot jets after I did it, Again same result. The main jets have been cleaned as well. I am wondering if its a sync isue. I was going to pull them apart again and check again but sometimes you just are over it, so I am going to let another  bike shop have a go I think. Its really pissing me off. I absolutely hate people working on my cars/ bikes other than me. I get so frustrated and annoyed if I cant do it myself. The people who did the club permit thought it was an old fuel issue, so what did they do? emptied the tank and filled it ALL the way to the top with new fuel. At some point they must not have heard me  when I said that the fuel is only a week or 2 old. It  Was in the to hard basket for them and they are a bike shop. So Noel I do agree with you, nobody knows how to fix old things and very few people have mechanical knowledge of pre fuel injection era. Now its throw it and replace it. That shits me bigtime.

Sorry about the bum time. You can fix it, trust me. And when you do it will probably be simple (hopefully ).

Diagnostics... Have you run a compression check, what do your plugs look like, hows the ignition wires, plug caps,

Before you put the carbs back in "just because" do a blow test into your carbs to insure the vacuum diaphragms are good. (pet peeve). Not the cause of your running problem but it's just a test to do before you put them back on. Make sure your manifold O rings going into the block, between the intake manifold and engine are good. They are a known spot to leak. Cheap and easy to replace when the carbs are off.

How many turns out are each of your fuel air mixture screws ? When you adjust the screws out your are adding fuel into the system. In is reducing the fuel.
With the choke off and warmed up how doe's it run around 3000 RPM ?

I know its a bit random but I hope that gives you some ideas and things to do. Give us some more data  . Hang in there, it's just a machine. Who is smarter you or it....?
George

[ribbert]

Jeff, if you're still in trouble by the weekend I can probably come down and have a look. Or if it's rideable, you could bring it to my place. I like my own tools. A fresh set of eyes might spot something. I hate seeing you so disheartened over what can't be that big a deal, particularly after some of the bad luck you've had and the time this has been going on.

Let me know

Noel

[FJ_Hooligan]

How many turns out are each of your fuel air mixture screws ? When you adjust the screws out your are adding fuel into the system. In is reducing the fuel.

I don't think that's technically correct.  According to what I've read in the past and studying the diagrams in the files, the mixture screws are varying the amount of a fuel/air mixture.  So it's a little more complicated than out = more fuel and in = less fuel. 

I think that based on the mixture that the pilot circuit is providing (which would be a function of the idle jet size and the air pilot jet size), you could be adding more or less of an idle mixture that is lean or rich.  If the mixture was rich, it would act like you describe.  But if the mixture in the idle circuit was lean, you'd be adding more of a lean mixture.  Would that be better or worse?  I still don't understand this very well.

I was just attempting to call attention to the fact that the mixture screws are NOT fuel screws.

[movenon]

It is my understanding that they meter/control  fuel not air. If they were on the opposite side they would be metering air. I might be off there but that basically my understanding. Might be wrong ? fuel /air or air /fuel ? You might be correct on the direction.... Noel.... ?

By knowing the number of turns out each carb fuel/air screw is when its running the best (I have seen them make no change in idle, which tells me something), might indicate a particular cylinder to look at. Just looking for clues to his problem.

George

[Jeff0308]

seems to run a lot better with choke on than off. However even when its warm it still misses and pops a little which I thought may be a lean fuel mixture. Keep in mind that the bike has virtually done nothing in 12 months other than the odd start up and tank kremed . The bike has only been out for a month in this time. I haven't (PULLED ) the carbis to bits as such. Thought I would try the pilot jets and a tin of carbi cleaner.. stupid me should know better. Was more bothered to the fact if I pull them totally apart I would get in more than a bit of bother. I haven't taken the inlet manifold off at all. So I cant see why the gaskets would be an issue if untouched, however stupid things are known to happen. The guy in the bike shop suggeested the gaskets as well....... Thanks Noel for the offer. Dont know if I can make it this weekend as got a few things on. I havent yet pulled it apart again as to many other things going on. Was going to today but got distracted.

[Jeff0308]

Just had a thought. Better not touch it tomorrow..... Its Friday the 13th.