Rich after warmup?

Hello everyone,

Having had my bike running again after problems with the starter last summer, starter seals leaked, oil/gunk got in, brushes wore down. NEW (different) one's on now!!

After running it for a while this summer, it's suddenly decided (from what I gather) to run rich once it's warmed up, so rich that the bike stalls (very easily) at low RPM, it can't idle when warm, but it seems to run alright at high RPM when warm. It starts fine, purrs like a kitten.

There was a problem when the seal (diaphragm?) on the petcock was spurting a bit when the pump inside it was cycling, but the 4 screws on the petcock were just loose, that's been fixed.

Anyway, after I tried to start it up this time (last time I had to walk a mile home with it...) after it had decided to quit (so, running for a while, perfectly, gets warm, dies at idle / cannot get to high enough RPM to not die...) I checked a plug, which is what told me it's rich, WAY rich... but the plug was dry after having had it turn over a few times (but not kick at all). I wouldn't say anything major has changed from last summer... New fuel's in the tank, in the fuel line, and in the float bowls (and my carb drain screws were only slightly mashed; I could undo and do them up again!


So, short version:
-Starts and runs fine when cold.
-After warmed up, it loses power at idle, eventually so much that it stops.

From my scatterbrained depiction of the problem, I am sure someone out there knows what the problem(s?) and any solutions are.



Just because I'm a pessimist, I have a hunch that one of / the only answer you're going to say is to disassemble and clean the carbs... Edit: found the clean the carbs link! (http://www.xjbikes.com/Forums/viewtopic/t=2908.html) Do I have to resynch them?... . Edit: found the synch the carbs link!(http://xjbikes.com/Forums/viewtopic/t=2132.html) YICS tool creation? found a link! (http://www.xs11.com/tips/norm/yics.htm). Or if you're in the greater Toronto (Ontario) area and know a good mechanic that knows YICS and will work on XJbikes, that would be helpful too!

-Matt

 

After reading through some of the archived threads, I am suspicious, and suspecting that it could be the floats sticking. Specifically after reading this thread:

http://www.xjbikes.com/Forums/viewtopic ... +idle.html

I should note that there is plenty of flow through the petcock, even though I didn't specifically mention it, it was tested via a beer bottle, almost a beer can as suggested in that thread

Anyway, my question is, how do I check these floats, I should also add now, I don't know how to remove the carbs :S -- yet.

 

you can check the float levels with the carbs on the bike, so long as the drain screws work, connect a short piece of clear pipe to the drain, pointed upwards, release the screw & fuel will flow up the pipe to the same level as inside the bowl, it shoud be about 2mm below the gasket line.

 

There are several good contacts on Toronto who might be able to help you straighten-out the problem you are having.

You ARE going to need to have some Carb work done! The question is:
Do you have the tools, skill and confidence to tackle the job yourself?

You are going to have to Pull the Carbs.
Clean them.
Inspect the Rubber Diaphragms for tear, abrasions and pin-holes.

You'll also have to do a refinishing of the Diaphragm Piston Bores.
This will eliminate the possibility that the Pistons are binding and sticking causing havoc with the Mixtures ... a problem you seem to be having.

 

Dismantling and cleaning your own carbs may seem daunting at first, but if you take your time it is easily accomplished.

Hardest part for me is getting the boots back on when I'm done

 

Thanks Rick. I got a shopping list for the parts to a YICS tool; I am assuming afterwards they have to be re-synchronised? I also have 2 muffin pans out

...But they are still empty


My fingers hurt after removing the carbs from the machine, I am concerned about the engine-side rubber things, they seem alright; I could reconnect them if I want, but they are breaking down slightly. Moreover, can I just use engine cleaner on the outside of the carbs? Or does it have to be carburator cleaner?

I was unable to procure a #6x32 threaded rod today, I will go to a steel-maker tomorrow when it's open to try to get one. YEA! YICS TOOL!!! YEA!

We'll see.

-Matt

 

Hello again.

So, I got the carbs out, and I'm not looking forward to putting them back in. I sprayed the outside with carb cleaner, as it was moderately oily and I got the float bowls off. I took a look in them, and I'd say they look prestine, I have a couple pictures, and the question to enforce or perhaps rediagnose the problem (obviously due to fear of taking apart the top end of the carburators!).

So it looks clean to me, but maybe it's not:



















I dunno, what do you think? Gotta open up the tops? I just want to make sure that it's required, as it could end up with an expensive trip to the mechanic!

-Matt

 

you've done the worst bit, there is more gubbins in the bottom than the top.

 

From the looks of the sediment you have in the bottoms of those Fuel Bowls; I'd say you should keep going and make sure all the Jets, Orifices and Metering Holes are clean and clear.

Pull the Pilot Jet
Pull the Main Jet and washer.
Get the Tops off and push-out the Brass Emulsion Tubes.
Clean it all.

While you have the Diaphragm Assemblies out; refinish the Diaphragm Piston Bores.
Get them free of oxidation and them shine them.

Flush the Pilot AIR Passage
Flush the Main AIR Passage

Get them Operating Room Clean before you reassemble them.

 

AND make sure you put the jets back into the right holes when you reassemble them. It will save you a "practice cleaning round" later down the road (in a couple days).

 

amen

 

UPDATE!

Well, I finally got at it. I meant to do it last week, but I forgot the carb.s at home...

Anyway, I have some pictures, the stuff looks really clean to me. Some of them are a bit blury, but I'll show you, someone can hopefully tell me what they think:



Outside beside the pilot screws, the 'choke' (mainly to look inside, it looks not bad from that POV?)


The plunger from the choke:


The main jet (the pilot jets are similarly coloured):


Other side:


The float hinge pillar (I think that's what it's called):


Other side:


The bottom of the hat:


The inside of the diaphragm(?):


The rubber+brass part of the diaphragm:


The other view of the rubber part:



If you say the word, I'll keep going through, keep cleaning. I have yet to open up the other 3 hats, one has a jammed screw which I will use an impact... screwdriver?? I think that's what you call it, on. So maybe if they are unclean I will keep going automatically.

Thanks (VERY MUCH!) for all your help so far!!

-Matt

 

I see gunk on them there slides!

Between that and the 'sediment' in those earlier float bowl pics, i'd guess you need a good 'all-over' carb cleaning!

 

Refinish the Diaphragm Piston Bores.
Use some Gray ScotchBrite Pad and scrub them until the Aluminum shines bright.

Press-out the Emulsion Tubes.
On the bottom of the carb, whehre to took-off the Main Jet ... there is a Washer to remove, too.
Set the Washer aside.

Now, press or tap out that Brass Tube where the Main Jet screwed into.
It goes out through the top of the Carb.
Its called an Emulsion Tube.
Clean the whole thing inside and outside.
Check EVERY Metering Port along the Outside Diameter.
You should be able too look through the holes on one side and see light through the holes on the other side.

The Emulsion Tubes NEED to be perfectly clean.
While the Emulsion Tubes are out ... shoot Carb Cleaner through the Main AIR Jet on the top of the Carb, below the rubber Diaphragm and look into the Center Hole where the Emulsion Tube was withdrawn to see the Carb Cleaner flowing out.

Emulsion Tube and Main Jet with Washer:

 

I have a similar issue with a bike I just got. However, I went through the carbs and I think my issue is the float levels. I can't get two if the drain screws out on the bowls. I have a way around this until I get some new drain screws. Will having the float levels low by a few millimeters cause the bike to run lean? Or do I have another issue?

 

If the Float Levels are just a hair low ... it's likely that you have some other issue causing the Lean condition.

Now, that everybody's bikes are starting to get close to 25~30 years old ... Manifold Leaks and the condition of the Rubber Diaphragms come into question.

You can probe for the Manifold Leaks with Propane Gas.
The Diaphragms you need to inspect.

Then, it might just be an issue of Mixtures. Getting the Mixtures on-the-nose is a matter of patience. But, with some diligence looking at the Plugs and just the right tweak of the Pilot Mixture Screws ... you can easily get it right.

One other cause might be Diaphragm Pistons Sticking, too. Cleaning the Diaphragm Piston Bores of oxidation will return the Pistons to friction free movement and improve performance greatly.

 

Hey Rick,

Thanks for the information, as always. I removed all the tubes, all of them are like this one, and I can see through all the holes.

The tubes:


The needle (straight enough? Is there "scoring" where the q-tip is? I cannot feel it with my fingernail, but I can see there are lines:



I could not upload that to thumbnail form, sorry!! It wouldn't let me.


Anyway, from the other picture I linked, are you able to tell what type of pilot screws I have? The factory-locked ones, or aftermarket ones, etc.?

Thanks in advance.

-Matt