running problems

[badams]

Hello gentlemen,

Fj1100 started to run very mildly choppy at about 1/4 to 1/2 throttle. I figured that I would take this time to install 40 pilots and smaller main's(have been running way to big).

Cleaned out the pilot and float systems with carb cleaner and compressed air. reinstalled and ran much worse than before.

So far I have pulled the carbs 4 times, dismantled and cleaned them. Check float height, fuel level, pressure tested float system and even tried a clean second carb bank. No luck!

Since then I have replaced the battery, spark plugs, plug caps, second set of ignition coils No change.

Just pulled the new plugs and they are wet/sooty.

Any Ideas?

Thank you

Brad

[Pat Conlon]

Sounds fat: Start with some fresh o rings on your float needle seats.

Double check your choke linkage. Make sure your choke circuits are off.

Our gravity fed FJ's have no fuel filter, just a screen on the petcock, so make sure your tank is clean, clean, clean.

Clean carbs are futile with a contaminated tank.

On the electrical side, clean and grease the contacts in your run/stop switch. This 12v circuit powers your igniter.

[badams]

done, done, clean. will try cleaning the switch.

Also lack of power Idle to full throttle.

It does seem like it is running fat. Getting tired of pulling carbs.

Any other ideas?

Thanks

[Pat Conlon]

....Just pulled the new plugs and they are wet/sooty.

Are all the plugs the same?

[badams]

yes

[Pat Conlon]

Think globally.
What would cause all cylinders to run fat all at once?

If an individual cylinder got rich, yea, its the carb or a bad plug, plug boot or plug wire.
If #1 and #4 got fat or #2 and #3, it's probably coil related. 1&4, 2&3 share the same coil
If all 4 cylinders got fat at the same time, and your choke linkage is ok, then it's ignition related. Something's causing a weak spark to all 4 cylinders.
A weak power supply to your ignition could cause this.

Clean your run/stop switch, check the wiring harness plug connections, see if that helps.

[badams]

ok, thanks. will start checking.

Getting bad flashbacks to the BMW R90

[Flynt]

done, done, clean. will try cleaning the switch.

Also lack of power Idle to full throttle.

It does seem like it is running fat. Getting tired of pulling carbs.

Any other ideas?

Thanks

So you changed pilots to 40 and mains to ?  What jets did you remove?  Do you have adjustable needles and what slot are they on if so?  Are the other bits in the carbs fresh?

Lastly...  what makes you think it is fat?  I've spent hundreds of hours (and dollars) making an AFR assumption without any data and then chasing my tail.  Turns out when a bike is way lean, you have to wind the throttle open so much it can actually sound and feel fat.  Look up the Factory Pro Mikuni CV tuning procedure and go through it top to bottom.  Repeat as necessary to get it right and you'll be a happy camper.  Once dialed, your FJ will remain a stable toy with minimal maintenance. 

The mods will kill you though.

Frank

[Flynt]

Getting tired of pulling carbs.

Oh.. and you're just getting started pulling carbs.  Get over it...  :big grin:

Frank

[badams]

Cleaned kill switch- no change.

since all 4 spark plugs look the same I pulled the carbs again and went back to the 37.5 pilots and 114 DJ mains that were originally in the bike when it was running good. Now the bike will start for a second or 2 and die. Choke makes no difference.

Could any other switches or relays cause a problem like the neutral or side stand sensors. I have swapped out both coils, TCI box and new s.p. caps, new battery with no change.

My new rear avon storm 3D max tire needs to be tested out.

[movenon]

Here is a cross conversion of main jet sizes. I can't testify as to accuracy but it looks like your DJ 114 is equivalent to a Mikuni 106.9.

http://www.triumphrat.net/hinckley-classic-triples/121732-good-chart-on-keihin-vs-mikuni-jet-sizes.html

That's half the story, what needle are you using ?  My carbs had a DJ "kit" in it.  I converted it all back to stock Mikuni parts including the diaphragm springs. Much happier now. I have something I can adjust as required.

Hope it helps. IMO don't mix DJ with Mikuni parts. At 0-1/4 throttle you are mostly on the pilots and fuel air screws, around 1/4 throttle you are coming on to the needle/jet combo around 3/4 throttle you are coming onto mainly just the jet size.

Randy at RPM has jets and just as nice ,adjustable needles.

As I brought the subject up here is a picture of the Mikuni spring vs the DJ spring for future information.



George

[Pat Conlon]

By pass the side stand kill switch.
Follow the wires up and find the plug on the left side. Unplug. Take 2 female spade connectors and make a wire jumper. Plug the females on the male prongs of the plug. The circuit must be closed for the bike to run.
Easily reversible if you find that the side stand switch is not the culprit.

[racerrad8]

Here is a cross conversion of main jet sizes. I can't testify as to accuracy but it looks like your DJ 114 is equivalent to a Mikuni 106.9.

George

That is a terrible chart for jet size comparison. Mikuni only make jets in flow rates not by hole size. So, all Mikuni jets are incrementally divided, i.e: 110, 112.5, 115, 117.5, 120...

Now, looking at the chart, they don't even have the actual Mikuni jet sizes listed, but have come up some other comparison number, like 106.9...

By the chart I have, the 114DJ jet is equal to a 107.5 Mikuni jet which is one size smaller than stock. But like George said, the needle and slide spring play a roll in the mid-range of the carb but once it is wide open, that is all main jet.

So, the bike ran before but poorly, and now it just starts & dies?

Randy - RPM

[badams]

sorry for the break in the thread. Had do deal with strokes/turret's(kidding) from this problem.

Bypassed kick stand-no change
Changed side stand relay-no change
Cleaned kill switch 2X-no change
Cleaned ignition switch-no change
Swapped both coils-no change
new plug caps-no change
new battery-no change

Carb setup is:
Stock mikuni  parts(40 pilots), and 110 DJ mains- I had DJ 114's in when it was running decent but rich.

I have seriously cleaned and checked the carbs 6X now. tried changing pilot and mains- not the problem.

Played with air mix screws which didn't seem to improve situation. Carbs synchronized.

All 4 new spark plugs are now dry fouled.

When I can get it running is backfires through all cylinders.

No confidence with electrical testing which is why I have been swapping parts with my parts bike.

[Pat Conlon]

When you say that your plugs are now "dry fouled" do you mean wet with gas?

Ohm check the resistance to your pick up coils. Unplug at the ignition box and check the circuit from there.

You should read 149-182 ohms at 68*F for each pick up coil.

I don't think this is it, if one pickup coil went bad, you would still be getting spark on the other 2 cylinders

I'm running out of ideas, unless the TCI ignition module is at fault.

Did you check to see that you are getting full voltage at your ignition TCI box? There is a 14 pin block wire connector between the run/stop switch and your ignition TCI box, did you check/clean that big plug?

You have an 1100 so that means you have a vacuum operated petcock on your tank. Perhaps that petcock is loosing vacuum and closing? You have 2 settings on the petcock lever 1) On and 2) Prime (P)
Move your petcock over to P which will open the flow of gas to your engine with no vacuum signal.
See if that makes a difference. This is only done for diagnostic purposes only. Do not leave the petcock in the Prime setting or you can free flow fuel, cause a (big) fire or fill up your crankcase with fuel.