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Cleaned carb problems

Started by Mark V, July 06, 2023, 11:08:38 AM

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Mark V

I cleaned out the carbs after my newly acquired 1984 FJ 1100 sat for 25 years.  Needless to say it was a hot mess.  I did get it to run for about 10 minutes, but the pilot air/fuel screws were completely turned out then stalled.  I went back in and cleaned the pilot jets again but it wont start with the screws 2.5 turns out.  I reused all of the existing parts and I do have a cheap rebuild kit coming.

My questions are: Can I test off of a temp fuel tank with the vacuum line to the tank blocked off and the air box disconnected?

The other issue is: With the air screws set at factory fuel is coming out above the air screws.  Maybe the floats are stuck?  I'm not sure.

FJmonkey

You can use an AUX tank and plug the vacuum line. Keep a fan blowing directly on the header pipes and engine block (no moving air, no cooling). One or more floats and or needle seats seems to be an issue. Carbs are too complex to me to use low cost kits. Having to buy another kit or parts and then removing and servicing the carbs again is real pain. Good luck, tell us how it works out. As a last resort, send them to RPM for a professional rebuild. Many report great results from RPM.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

Waiex191

You really have to take them all the way apart to clean them - ask me how I know!
Bryan
1989 FJ1200
1981 Suzuki GN400
Poplar Grove, IL
 

Old Rider

Quote from: Waiex191 on July 06, 2023, 01:12:25 PM
You really have to take them all the way apart to clean them - ask me how I know!
I can add you may need to do that 2 or 3 times to get them clean dont ask  :biggrin:

Mark V  i think maybe the floats are set wrong and / or the small orings on the end of idle jet screws is missing or broken since you can see fuel around them

Motofun

A trick for the tiny little openings is to take the red straw that comes with the carb cleaner and sand one end into a sharp point.  Shove that point into the openings and squirt away.  Wear eye protection!   :Facepalm:
'75 Honda CB400F
'85 Yamaha RZ350
'85 Yamaha FJ1100
'89 Yamaha FJ1200
'09 Yamaha 125 Zuma
'09 Kawasaki KZ110 (grand kids)
'13 Suzuki GSXR 750 (track)
'14 Yamaha FZ-09
'23 Yamaha Tenere 7
SOLD: CBX,RZ500,Ninja 650,CB400F,V45 Sabre,CB700SC,R1,GSXR1000R

Mark V

Quote from: Old Rider on July 06, 2023, 03:25:58 PM
Quote from: Waiex191 on July 06, 2023, 01:12:25 PM
You really have to take them all the way apart to clean them - ask me how I know!
I can add you may need to do that 2 or 3 times to get them clean dont ask  :biggrin:

Mark V  i think maybe the floats are set wrong and / or the small orings on the end of idle jet screws is missing or broken since you can see fuel around them

I took removed all the parts and cooked them in the ultrasonic bath several times, but didn't disassemble the linkages and dropped the whole assembly in the tank.  The float pins were glued in and took quite a bit of work to get out.  I bent one of the pins during removal and tried to straighten it out but its probably sticking.  I did get the washers and old o-rings out of the air jet and replaced with new o rings.  I have rebuilt single carb on my KLR and it turned out great but but not a quad set.  I want to use the basic parts from the cheap kit and if I need to go further I will buy japanese.  Thanks

Waiex191

Did you set the float height?  Remove and clean the emulsion tubes?  How is the passage from the float bowl to the enriching circuit? 
Bryan
1989 FJ1200
1981 Suzuki GN400
Poplar Grove, IL
 

balky1

And to go back to your first post - it won't run right with airbox disconnected.


FJ 1100, 1985, sold
FJR 1300, 2009

Pat Conlon

Quote from: balky1 on July 12, 2023, 05:28:19 AM
And to go back to your first post - it won't run right with airbox disconnected.

Not true. The bike should run fine with the air box disconnected. Many of us no longer have our air boxes.
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

balky1

Quote from: Pat Conlon on July 12, 2023, 09:00:27 AM
Quote from: balky1 on July 12, 2023, 05:28:19 AM
And to go back to your first post - it won't run right with airbox disconnected.

Not true. The bike should run fine with the air box disconnected. Many of us no longer have our air boxes.

Yes, but you've changed the jetting to accompany that, right? I tried what he's saying.


FJ 1100, 1985, sold
FJR 1300, 2009

Mark V



Yes, but you've changed the jetting to accompany that, right? I tried what he's saying.
[/quote]

I rebuilt the carbs with new needle valves, pilot jets, main jets, air screws and adjusted the float heights. But the air screws need to be turned out 4.5 turns out to idle.  Maybe the pilot jets size needs to increased?

Pat Conlon

Depending on your import region, regulations dictated different pilot jet sizes depending on smog rules. For example USA FJ's used a lean #37.5 pilot and the same model imported to Australia used a richer #42.5 pilot.
So, my question to you is....what size pilot jet did you install?
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

tymewyse

Hopefully not to dumb of a question. I have rebuilt my carbs and want to know what people have used for jetting. I ordered the rebuild kits from RPM and since the bike came with a Vance and Hines exhaust and K&N pods I just was curious, I do have the stock airbox available. I kept the same jetting in that came with the bike since I assumed (we all know what that means though) it was correct but when it is throttles right off idle is pops and sputters and will backfire now. I'm in NW Oregon at about 1000 ft. Just trying to get some basic direction.

Pat Conlon

What do you have in there now?
1) Free Owners Manual download: https://tinyurl.com/fmsz7hk9
2) Don't store your FJ with E10 fuel https://tinyurl.com/3cjrfct5
3) Replace your old stock rubber brake lines.
4) Important items for the '84-87 FJ's:
Safety wire: https://tinyurl.com/99zp8ufh
Fuel line: https://tinyurl.com/bdff9bf3

RPM - Robert

Sounds like the carbs are still dirty TBH.

But as far as jetting 1100/1200, shrouded/unshrouded, flat bottom/curved bottom slides, jet sizes, main jet needle number/overall length (1100 is shorter than the 1200) settings if adjustable/someone shimmed?