new to site and running problems which i hope someone can help me with

[amocjim]

hello all, i am new to the site but have owned my fj1200 for 6months now. during this time i have had nothing but problems and am praying that someone here can help me before i loose my mind. the bike is an fj1200 1991 engine, the bike is a streched out chopper. the bike has an aftermarket hd petrol tank on it with a standard harley fuel tap. the bike quite often runs like it is out of petrol but if you are gental with the throttle it can run ok, try to accelerate and again its like its out of fuel and runs on two to three cylinders. the bike has k&n filters and straight through pipes, i have had the carbs balanced....still no change. could it be simple like you need a vacuum tap? or coil breaking down., i love the bike and always had fj1100 and 1200's and really dont want to lose the love for the bike and part ways with it, i just cant take no more.....just to add i have also already put in new plugs and caps and had the bike profeshionaly re-wired ground up. thanks to anyone who may be able to help me at my time of need. also new to site so hello to all excisiting members

[Harvy]

SO its a '91 FJ with '91 carbs and a fuel pump in line between the fuel tank and the carbs?



Harvy

[amocjim]

i beliece they are late 80's carbs but i changed all the inners to the 1991 ones that came with the new engine i brought, the engine is a 91 plate. thanks for getting back to me. jimi

[FJmonkey]

Welcome to the nut house. If you are running with the 91 carbs then you might have issues if you don't have a fuel pump. however I am running with FP carbs on my gravity feed 86' and only have problems with a low tank at freeway speeds. If your floats are set too low you will not have enough fuel in the bowls. The FJ engine is simple enough and there are enough years of experience to get you sorted out and in the Kookaloo zone.

[amocjim]

sorry didnt put before the bike has no fuel pump

[amocjim]

i am not sure how you would change the height of the floats, is there a trick to it or a good height to change them to, someone mentioned a vacuum tap?

[FJmonkey]

Then low floats will make it worse. How many fuel lines feed the carbs? One to the center between carbs 2 and 3. Or two with a line feeding between 1 and 2 and a second line between 3 and 4. What size are the fule lines, 6 mm or 10 mm?

[amocjim]

standard size fuel hose, one going into the main feed in the centre of the carbs. sorry not to mechanical minded like to ride it.....if i can anyways

[amocjim]

sorry just to add, i have an in-line clear glass fuel filter which looks like it is always full of fuel

[Harvy]

i beliece they are late 80's carbs but i changed all the inners to the 1991 ones that came with the new engine i brought, the engine is a 91 plate. thanks for getting back to me. jimi

Jimi, '91 carbs required a fuel pump as the inlet under the float needle is smaller diameter (ie the hole that the fuel flows through is smaller)...... if you still have the older needle and seat stuff, swap back to that and it may just clear up your problem (or get a fuel pump).

Harvy

[Harvy]

amoc = Aston Martin Owners Club?


Cheers
Harvy

[amocjim]

we have used the original bottom needles etc which i beleive is mid 80's spec, another guy said abot possibly increasing the height of the floats, do you think this may be an option., or i can pick up a 2nd hand fuel pump for £40, do you think the details i put this would cure? amoc is american motorcycle owners club i also own a 1340 evo harley chopper

[Flying Scotsman]

Get rid of the filter and see what happens.Should be one in gas tank I think.No fuel pump = no inline filter.

[amocjim]

i will certainly give it a go, by far the cheapest option and simple enough for me to do. cheers for your input. jimi

[FJmonkey]

Check your petrol tank for a filter, the FJ tanks have a filter screen built into the petcock, your after market HD tank may not. Either way the gravity fed FJ carbs did not come with an in-line filter. Regarding your fuel lines, STANDARD for gravity feed is 10MM, Fuel pump is 6MM, based on the ID of the hose. If you have FP carbs and 6MM hose and a fuel filter then you have three points of restriction. Good luck...