running rough and exhaust popping

[scarylarry]

I have an '87 fj1200 which was running great, best ever.
now this morning, rough running and exhaust popping.
do you think one of the idle jets clogged?
it's been 2 years since I've had the carbs off.

btw, I just put rpm's voltage regulator on. I don't think that should be the problem.

[movenon]

I have an other members FJ here that was doing the same thing when cold.  After checking for air leaks and a good night sleep I took a close look at the choke cable and choke rod.  Sure enough, a screw had fallen out of the choke piston actuator on the # 4 carb...  Make sure all the plungers are operating correctly.

Just something to check before you pull the carbs if you are headed that way.  Pilot jets do plug up pretty easy.  All boils down to probably a lean mixture in one or more carbs.
George

[scarylarry]

thanks, i'll check for that.

I might also just try running some carb cleaner thru it first if your suggestion is not the problem.
I should probably take them apart and clean them, tho.

[movenon]

thanks, i'll check for that.

I might also just try running some carb cleaner thru it first if your suggestion is not the problem.
I should probably take them apart and clean them, tho.

While you are at it check the intake manifold boots.  Make sure they are snug and not leaking.  Hate to see anyone dig in to deep just to find out it was something simple later. 
George

[Bminder]

I don't think the idle/pilot jets would cause the symptoms you're describing. They mostly affect idle quality and RPMs under 2000 or so.

[movenon]

I don't think the idle/pilot jets would cause the symptoms you're describing. They mostly affect idle quality and RPMs under 2000 or so.

It is challenging to troubleshoot a problem via the internet.  As Larry stated the problem we don't have all the facts so we have to start with the basic things first.  A 2000 RPM number is nice but when it comes to the carbs it doesn't tell much other than it runs.  I can hit above 2000 RPM and be under 1/4 throttle easily.  0 - 1/4 throttle position the fuel/air screws and pilot jets have the most effect.  Some would be surprised how much of time you spend in that range.  Take some tape or chalk and mark the 1/4 throttle points on your grip.

When evaluating a running problem related to the carbs, the throttle position and conditions (choke on/off, cold, hot) tell me more than RPM as far as where to look for a carb problem.  That's basically how I look at a carb problem. But I am no "carb" guru either.
George



 

[scarylarry]

as i stated before, the bike was running great and when i started it this morning, it started ok, but idled rough and the exhaust was popping.
took the choke off as normal, and it still was rough and popping exhaust.  throttled up, same results.  actually started getting worse
as it warmed up. ran it up and down the street same results.

well, I took the carbs apart, everything looked clean.  cleaned out jets, orifices, etc. with carb cleaner and blew air thru everything.
put everything back together and still the same problem, but this time there was gas coming out one of the drain hoses.
took that carb apart again and it looks like the diaphragm was worn thru where it sits in the channel it
nests. i patched it with plasti-dip spray.  hopefully that was the problem.

[Pat Conlon]

Which carb was flooding, which hose? Take that carb's float needle seat out and replace the o ring.

If this solves the problem (I think it will) plan on doing this to the other 3 carbs.

Between stuck floats or debris in the needle seat.....bad float needle seat o rings are very high on the list as to the reason why your carb floods.

I don't think your slide diaphragm is the reason you're flooding.

[scarylarry]

thanks Pat!
I will do that when I get the chance.  it was just frustrating that the night before it was running great and the
next morning it was running like crap

ps  would you happen to know the size if the o ring for the needle seat?

ppss  nevermind...I found it.   search is your friend 

[movenon]

thanks Pat!
I will do that when I get the chance.  it was just frustrating that the night before it was running great and the
next morning it was running like crap

ps  would you happen to know the size if the o ring for the needle seat?

ppss  nevermind...I found it.   search is your friend 

Needle and seat is 7mm ID by 1.5mm X-section, but I use a slightly larger 7.1mm ID by 1.6mm X-section Viton.  I got mine from Oringsandmore.com out of Richmond, Va but you have to buy a bag of them (25). They are inexpensive. 

But it might be better to get a O ring kit from Randy at RPM and then you would have a complete set.  There are 4 small ones in the fuel air screws also and if you have the carbs off how about the larger o rings between the head and intake manifold ?  I think they come in the kit plus the o rings that go on the carb connectors and tee's.

When you cleaned the jets did you remove the pilot jets and take out the fuel air screws ? 
George

[scarylarry]

Needle and seat is 7mm ID by 1.5mm X-section, but I use a slightly larger 7.1mm ID by 1.6mm X-section Viton.  I got mine from Oringsandmore.com out of Richmond, Va but you have to buy a bag of them (25). They are inexpensive.  

But it might be better to get a O ring kit from Randy at RPM and then you would have a complete set.  There are 4 small ones in the fuel air screws also and if you have the carbs off how about the larger o rings between the head and intake manifold ?  I think they come in the kit plus the o rings that go on the carb connectors and tee's.

When you cleaned the jets did you remove the pilot jets and take out the fuel air screws ?  
George



[/quote]

just ordered some from McMaster Carr.  I got rpm's kit 2 years ago.

yes, I did remove pilot jets and fuel/air screws   cleaned 'em up real good

[movenon]

Needle and seat is 7mm ID by 1.5mm X-section, but I use a slightly larger 7.1mm ID by 1.6mm X-section Viton.  I got mine from Oringsandmore.com out of Richmond, Va but you have to buy a bag of them (25). They are inexpensive.  

But it might be better to get a O ring kit from Randy at RPM and then you would have a complete set.  There are 4 small ones in the fuel air screws also and if you have the carbs off how about the larger o rings between the head and intake manifold ?  I think they come in the kit plus the o rings that go on the carb connectors and tee's.

When you cleaned the jets did you remove the pilot jets and take out the fuel air screws ?  
George

just ordered some from McMaster Carr.  I got rpm's kit 2 years ago.

yes, I did remove pilot jets and fuel/air screws   cleaned 'em up real good
[/quote]

OK on the o rings.  Please forgive my question on the jets, via the internet it is hard to tell sometimes how much experience or ability a person has. 
If I say that "I rebuilt my carbs",  to you that might mean a lot of things. You would have to ask me some questions to get "zeroed" in on what I consider "rebuilding"   

As a note the last time I had my carbs off I adjusted the float levels and made a minor mod.  When I reinstalled them, low and behold one of then leaked.... I tapped the bowl and it stopped.  That was 4 months ago and no leak yet.  Maybe the float was slightly bound or a little off center, I don't know but it went away.
George

[scarylarry]

 no offense taken George,  you don't know me from adam or my abilities.

I'm just glad you were able to give me some suggestions so I'm not chasing my tail!

I was hoping it was just a stuck float, but when I got it apart, it moved freely.  I did give a few raps with
a screwdriver handle before taking the carbs back off, but no luck.
I'm just gonna replace the O-rings when they come in and go from there.

Thanks again,
Larry

[scarylarry]

just a follow up...

replaced all 4 float needle seat O-rings,  cleaned up spark plugs, found my petcock was stuck open and fixed that.
aaaannnndddd........success!    bike runs like it did before all the problems.

thanks for all the help guys!   

Larry

[Pat Conlon]

Good deal Larry...Kudos for sticking with it