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
SO its a '91 FJ with '91 carbs and a fuel pump in line between the fuel tank and the carbs?
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
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.
sorry didnt put before the bike has no fuel pump
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????
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?
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
sorry just to add, i have an in-line clear glass fuel filter which looks like it is always full of fuel
Quote from: amocjim on February 10, 2013, 03:07:08 PM
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
amoc = Aston Martin Owners Club?
Cheers
Harvy
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
Get rid of the filter and see what happens.Should be one in gas tank I think.No fuel pump = no inline filter.
i will certainly give it a go, by far the cheapest option and simple enough for me to do. cheers for your input. jimi
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...
thanks loads for your help. i will check the size of hose and also remove the fuel filter and see what happens,
Quote from: amocjim on February 10, 2013, 04:49:11 PM
thanks loads for your help. i will check the size of hose and also remove the fuel filter and see what happens,
I just re-read you post on the hoses, you most likely have 6 MM, as you have one hose feeding to the center of the carbs. The fitting is 6 MM so putting a 10 MM hose on will not fit nor will it help, the 6 MM fitting is the restriction. As a reminder, I am using carbs set up the same way so they can work.
Just as an extension to this if you decide to go with a fuel pump you don't have to use the FJ pump as they are outrageously priced I remember someone saying you could use a Nissan one I think ??
Welcome !
I would pull the carb's, remove the bowls, change out the inlet needle and seats to gravity feed units, adjust the floats to factory spec's and while the carbs are out blow test the diaphragms. Reinstall. Make sure your tank has a method to get air in it as your fuel is drawn down (air vent). To start with. There's a lot more things to check in the carbs but that is what I would do first. Use a fuel filter that isn't to restrictive.
Good luck. It can be fixed. And you can do it :). Don't get frustrated there is plenty of help here.
George
The float needle jets in your carbs are probably the small ones that require a fuel pump, especially if you don't have enough height (head) between the fuel tap outlet and your carb's fuel inlet.
You can remedy this problem in one of 3 ways:
1. Put a low pressure fuel pump in between the tank and the carbs
2. Change the needle valve jets to the earlier 2.3mm jets
3. Raise the fuel tank.
Arnie
Wow, already a bunch of noise on this thread.
I agree with removing the in-line filter, but also check 2 other easy things before pulling everything apart.
Make sure the tank is venting properly and the vacuum line to the petrcock is in good shape.
Or, try running with the petcock in the PRIME position.
I'm running late model carbs on my '85 (with no fuel pump) and have no problems with fuel delivery.
DavidR.
David, you missed the part were he has a HD type tank, so no vacuum petcock..(Dyna went out on Friday)...
In addition to the larger fuel inlet size Monkey pointed out, the gravity fed carbs also had 2 fuel inlets (between 1/2 and 3/4) not just one inlet, like the fuel pump models.
Send the carbs to Randy@RPM and he will convert them over to gravity carbs for you....
Cheers, don't give up..
Quote from: Pat Conlon on February 10, 2013, 09:58:55 PM
Send the carbs to Randy@RPM and he will convert them over to gravity carbs for you....
Pat....I think jimi is in the UK?
Harvy
thanks for all the in-put i have had in regards to my bike., the site is great and i plan on being a member for some time, yes i am based in th uk...havnt set my profile yet.,
after all the points noted i have checked ebay and found a fuel pump for just £40. today i will try and remove the in-line fuel filter and see if this improves the problem, if it does not i will order the pump from ebay and add.... i hope that this will finally sort the problem and i can just enjoy riding the bike,
again thanks for all your help and hope to speak again in the future.
i will update again hopefully once im all sorted.
cheers jimi
lots of great info already posted, try this first , remove your gas cap and ride it to see if you are having a vacuum lock problem . use a rag that can breath so you don't spill gas all over yourself.
gravity fed fj's do not like in line fuel filters.
thank you for the extra in-put i am up for trying anything so that it works, i today i have ordered an in-line fuel pump and will also remove the filter fingers crossed.
thanks again
Quote from: amocjim on February 11, 2013, 02:52:51 PM
thank you for the extra in-put i am up for trying anything so that it works, i today i have ordered an in-line fuel pump and will also remove the filter fingers crossed.
thanks again
Once the pump is in place the filter should be ok to use. Try it first witout, if all is fine then put it back. If it works well with the filter then keep it, and keep your carbs and engine cleaner.