FJ1200 running problems - ongoing saga!

[BristolFJ12Russ]

When I bought it I took it for a few short rides - no issues. One day it really didnt want to run and was only runing on a few cylinders. I thought it was dirt in the carbs so cleaned them out - pilot jets werent great so took the opportunity to replace. No change. It seemed like it could be ignition issues so i replaced the coils - no change - I then found that one of the plugs was faulty, so replaced all and it then idled well but would bog down/had no power.

To me it seems like its got to be the carbs, I just cant tell what difference it is making when i pull it apart and rebuild it. Everytime it purrs after the build and im grinning like an idiot for about 3 miles before the issues start.. The issues are that it will idle pretty happily but opening the throttle past 3k will result in the engine 'hunting' and dying out. Adding choke just makes things worse.


The bike is factory engine wise other than a free flow exhaust.

So far I have:
Changed coils, spark plugs
changed the fuel
new fuel filter
replaced carb gaskets, float needles, idle jets, main jets,
new battery

Diagnositics
Tried running with petrol cap open and shut (no difference)
Checked pump operation
Checked float levels
checked diaphram for damage
reset mixture setting to factory (+plus 1 turn to take into account the exhaust)
Inspected fuel bowls (clean)

the most recent item was the float needles - i though perhaps it was getting over fuelled. After I rebuilt it all - again, runs perfectly for 3 miles and then i have the issues.


any ideas?

[ryanschoebel]

What year is it? It seems to me that if those sort of things are happenings,you are running out of something once the bike gets nice and hot. I would check petcock, maybe something is getting clogged or gummed? I would also look at air filters, and make sure that they are passing enough air. Many on here know more than me though

[FJ_Hooligan]

Plug wires or caps?

Try bypassing the pump.  Check ground lead to the engine case.

Stock ignition or aftermarket?

[red]

When I bought it I took it for a few short rides - no issues.  After I rebuilt it all - again, runs perfectly for 3 miles and then i have the issues.  any ideas?

BristolFJ12Russ,

It sounds about like your in-tank fuel screen (or the fuel filter, if you have one) is getting clogged.  After the bike sits a while, the bike may run again if enough dirt floats away from the screen or filter element.

If you have a fuel filter, remove it and try to blow air through the filter, in the direction that gasoline flows.  If there is more resistance to air flow than in a new filter, then install the new filter.

Use a long hose, large enough for a marble to pass through, and siphon out a gallon or three of gasoline from the tank, at the bottom of the tank around the gas filter screen.  Look at what siphons into your catch tank, and if you get much foreign matter, shake the bike vigorously and repeat the process, until the gasoline comes out without any particles in it.  You can let the gasoline in the catch tank settle for a while, and then pour most of the gasoline back into vehicles, all but the dirty last cupful or so.  You may want to remove the fuel petcock to inspect the in-tank screen, if you find that dirt in the gasoline is the problem.

Do all of this work outdoors, so no gasoline fumes can accumulate inside any structure.  Keep us posted.

[andyoutandabout]

Russ, fuel filters vary by year, so hence the year ask. What's the inside of the tank like? I recently bought a uk bike and the tank had enough to warrant a clean and under tank filter replacement. These are easily available and I think they cost about 7 quid each. I ended up buying three just because.
Anyway, the carb experts abound here, so you're in the right place.
Are you in Bristol England? I went to Uni in Bath, so know Bristol well. Good times.

[Old Rider]

It sounds like your fuelline is getting kinked check that its routed exatly as on the picture on the airfilterbox and that its not to long .If its kinked a little you can ride about 2-3 kilometers and then it losing power and gets chooked.When you wait a while the carbs slowly fills up again and you can ride for 2-3kilometers.
And i forgot to say if its one of the early models without fuelpump you can not have inline fuelfilter i think

[T Legg]

I've had my fuel lines kink and run out of fuel several times.good call.

[BristolFJ12Russ]

Just as an update - i checked the fuel line for kinks and its fine.  I used a petrol can as a temporary fuel tank - direct to the fuel pump - by passing the fuel filter (fuel filter is transparent and looks clean)

starts up easily and idles, sounds healthy - no popping, even idle - all cylinders but at 3k rpm hunts and dies out again.

[krusty]

Fuel cap not venting? Whe it starts playing up try releasing the fuel cap and see if anything changes.

[BristolFJ12Russ]

Just as an update - i checked the fuel line for kinks and its fine.  I used a petrol can as a temporary fuel tank - direct to the fuel pump - by passing the fuel filter (fuel filter is transparent and looks clean)

starts up easily and idles, sounds healthy - no popping, even idle - all cylinders but at 3k rpm hunts and dies out again.

[Millietant]

Just as an update - i checked the fuel line for kinks and its fine.  I used a petrol can as a temporary fuel tank - direct to the fuel pump - by passing the fuel filter (fuel filter is transparent and looks clean)

starts up easily and idles, sounds healthy - no popping, even idle - all cylinders but at 3k rpm hunts and dies out again.

Where are you from Russ - Bristol UK, Bristol UK, Bristol AUS, Bristol CAN ?

[BristolFJ12Russ]

So these jets were new, only had a few miles on them (see pic)

I have a theory which is useful to share....

The previous owner had the tank sealed after pinholes had appeared.  And had no issues.   Neither did I until I added some redex carb cleaner to the tank.  It was very soon after this that i started having problems.

Now the gunk that was all over the jets has a glueish type quality.  My guess is that the addititive I put in has affected the sealant causinng it to disolve...

Anyway.  Whilst I had the tank reversed on the seat i managed to knock it off causing a good sized dent.   Since its full of random gunk anyway, I think it is time for a good clean second hand tank - if anyone has one please pm me!

I have taken the carb apart completely now, everything off needle valves, mixture screws the lot and will run compressed air through it...

ill post an update when I get a new tank on it!

[BristolFJ12Russ]

Just as an update - i checked the fuel line for kinks and its fine.  I used a petrol can as a temporary fuel tank - direct to the fuel pump - by passing the fuel filter (fuel filter is transparent and looks clean)

starts up easily and idles, sounds healthy - no popping, even idle - all cylinders but at 3k rpm hunts and dies out again.

Where are you from Russ - Bristol UK, Bristol UK, Bristol AUS, Bristol CAN ?

7

Bristol UK

[ryanschoebel]

There's the ticket! You can look in the parts available / for sale section here on the forum, or there are some models available on Ebay and the like if you are willing to search around!

[red]

So these jets were new, only had a few miles on them (see pic)  I have a theory which is useful to share....  The previous owner had the tank sealed after pinholes had appeared.  And had no issues.   Neither did I until I added some redex carb cleaner to the tank.  It was very soon after this that i started having problems.  Now the gunk that was all over the jets has a glueish type quality.  My guess is that the addititive I put in has affected the sealant causinng it to disolve...

Russ,

I would expect that you are right, and maybe the fuel filter has been clogged completely and "blown out" inside.  Anyway, by the look of your jet, I would expect the fuel tubing from the tank to the carbs to be fouled as well.  I would replace all of the fuel lines and the fuel filter, at this time.  If you need to make bends in the new fuel lines, I would use larger (than the OEM) fuel tubing, with properly bent metal tubing at every bend, and strong metal Tee fittings for any Tee connections, with tiny hose clamps at every connection.  I suggest that you do not use any parts for the fuel lines that are smaller (inside diameter) than the OEM fuel tubing.
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