Need carb tuning advice

Hi all, just registered. I am an owner of an 81 Maxim XJ550. Unfortunately I have neglected the old girl and left her sitting idle with gas in the tank for over 5 years!! I know...I do not deserve her. I finally found myself in a financial position to start enjoying her company again....so I dusted her off, cleaned out her carbs and she fired right up...not exactly purring like a kittken...but not bad considering I had not rebuilt the carbs...just cleaned them. So, I got out the carbtune and colortune....and began to tweak her to the best of my ability. By the time I was done things were much better....however not as good as it could be. The funny thing was when I was color-tuning #1, there was NO blue flame...no white...no nothing. At first I thought the colortunre was all clogged up, but I checked the glass and it was clean. So, in the end I ended up backing out the mixture screw on #1 way out....and low and behold I started to see some intermittent blue flame on...but certainly not steady like the others. This is where I need help. The carbs are synced pretty well (considering) and all of the other cylinders look good.
Symptoms: If I adjust the mixture screw down, cylinder stops firing at 1100 RPMs (my carb tuning RPM). If I start backing the mixture screw out, it will eventually start firing intermittent blue on colortune....but I can definitely hear the bike missing at idle. If I rev the engine....colortune on #1 goes more solid blue...but never turns yellow like other cylinders. Bike feels underpowered when riding.
When I originally cleaned the carbs I thoroughly soaked them for 24 hours and maually cleaned out all of the jets and anywhere I could get carb cleaner or air.
So, all you car tuning gurus out there? Is there a particular jet or place in the #1 carb I need to try to clean more? Should I purchase a rebuild kit for all of the carbs (the rest seem to be running great) since it was sitting so long? Should I try the old 50% SeaFoam trick?
Thanks is advance for your help. It's good to be back in the XJ world again.
Regards,

Curt

 

Check fuel level in bowl #1, check diaphragms for holes & generally for air leaks.

 

There are 2 paths ahead of you:
One you are guaranteed success, but it's expensive and time consuming.
You ruined your throttle shaft seals, need to completely clean DISMANTLED carbs, check or set your valve adjustment, check float levels, and many other things detailed in a few long articles on this site.

The other path is chasing 1 symptom at a time, and it's expensive and time consuming.

Welcome to the site !!

 

Here's the Good News.
There are Replacement Diaphragm Rubbers available that are designed to fit without a Securing Bushing.
And, ... they are not at all as expensive as a Replacement Diaphragm Piston Assy or the old fashioned re-bonding treatment.
They're like 20-Bucks a pop.
Well worth the dough.
Investigate.

Bite a Bullet and Overhaul the Carbs.
Do them in Stages so you don't get overwhelmed.
Even if you bought a spare set off a running bike; chances are they are going to need to be re-habed too.

There's no dodging the need to Overhaul those Carbs if you soaked them in Dip.

Even if you soaked them in a safe cleaner; 30 years is a long time.

 

And I would almost guarantee that the enrichment curcuit in the float bowl is still plugged. Time to pull the carbs, and do them right.

Ghost

 

OK, I left off some important details, that I believe made you assume this is my first carb cleaning rodeo....I'm not saying I am a guru, but I am certainly no moron either .
:
1. I dismantled the carbs, removed all rubber, including diaphragms before soaking. I DID NOT just soak the carbs assembled as a whole.
2. My first carb tuning step was to check the float levels.....all set good.
3. When I had the carbs apart I looked at the diaphragms and they seemed to be in good condition...no obvious tears or cracking. Is there anyway to test them?
4. No obvious wear on the mixture screws or float needle seat......although that is not always obvious by eyeballing.

I am thinking something is still partially clogged as well on carb #1. I fully intend on attempting to clean #1 again......but I was hoping for some advice based on my symptoms on where to look deeper.

Can someone elaborate on this a little more? : "And I would almost guarantee that the enrichment circuit in the float bowl is still plugged."

Now that you know things are not as bad as you first assumed....any other advice?

Thanks for your time and advice,

Curt

 

In the float bowl. There is a tiny passage that supplies fuel to the enrichment/pilot curcuit. These passages are a royal PITA to get clean. With 5 years of dried fuel I would almost bet that they are still plugged.

You can get a special long drill bit from XJ4ever to help clean these pasages.

The clue that you had to keep turning out the pilot screw was what shows it to still be plugged.

Ghost

 

This will explain it with much better detail

HOW TO: Clean the Enrichment Circuit Well

Ghost

 

The enrichment well orifice only comes into play if the choke lever is moved. He needs to concentrate on the pilot circuit and pilot jets.

MN

 

Remember-all the time spent on tuning the carbs will be worthless if the valves are not in spec. Did you check/adjust the valves before starting in with carb tuning? Good luck.

 

You say you removed all the rubber components before soaking, did you fit NEW throttle shaft seals ?

 

Don't cheap out and be sure and replace your float needle valves otherwise you might ruin 2 oil changes with gas. Don't ask me how I know.