Hi all, bike refuses to rev, have changed coils, ignitor box, coil pick up, checked for dodgy wires ect ect, only thing i havn done is take the carbs out , would float height blocked jets ect cause this, using air pods and 4 into one system, have also done the relay coil mod and had the advance 5deg plate on , was playing up before the mods , any ideas anybody ?
carbs.
Use to own an 86 vulcan and it did the exact same thing, got carbs freshly rebuilt and rode like a champ
Thanks, at least im not the only one, ill tear the carbs out again and check float levels , im hoping she,s just starved of fuel, as it starts fine and idles when warm
check the carb diaphrams for tears.
check the main jets and emulsion tubes for blockage..... those little holes are easy to get clogged up
KOokaloo! (i hope you get yours back soon)
diaphrams are like new, changed when i found holes before, jets are clear, hmmm emulsion tubes u say didnt even bother checking them just b4 , dam dam ***k , will pop the carbs again , thankr mate :). . would a plug cap cause the problem ?, have multi metered them seem ok .
the small holes in the emulsion tubes function right at the point where the engine goes into high RPMs so i would bet thats where the problem is.
Kookaloo!
Quote from: fj11.5 on June 27, 2011, 01:04:26 AM
diaphrams are like new, changed when i found holes before, jets are clear, hmmm emulsion tubes u say didnt even bother checking them just b4 , dam dam ***k , will pop the carbs again , thankr mate :). . would a plug cap cause the problem ?, have multi metered them seem ok .
They'd have to be really, really plugged though.
Clean em and see, can't hurt to have more things clean within the carbs, it's another thing to check off the list!
Ok, on a roll, checked 2 before bed and both tubes had a few holes blocked , will sort out the other 2 today, thanks guys ,will report back to HQ when she lives again
Hi again, checked the other 2 emulsion tubes all clear, , maybe ive done the float levels wrong ? seems like its hitting a rev limiter with huge back firing, flamer out the pipe ect, on the plus side she starts and idles great haha
Quote from: fj11.5 on June 27, 2011, 09:09:09 PM
Hi again, checked the other 2 emulsion tubes all clear, , maybe ive done the float levels wrong ? seems like its hitting a rev limiter with huge back firing, flamer out the pipe ect, on the plus side she starts and idles great haha
Mate, that sounds quite familiar, but in my case it was at 6000rpm. After replacing plugs and leads to no avail, I bit the bullet and bought a Dyna2000 ignition........all better now!
Harvy
Hey harvey, thanks mate, i may just have to end up doing something like that,
Hmmmm...'84 FJ ignitor uses a vacuum advance...so,
1) Is the vacuum hose hooked up to the igniter box? (off #3 carb)
2) If so, disconnect the line at the carb, stick it in your mouth and suck, does it hold a vacuum?
Not sure that's the reason, Even with the vacuum line disconnected the bike should rev past 4k....It's gotta be gas related...
3) Check your fuel line routing....follow oem, critical on early gravity feed bikes... This is a very common problem, pinched fuel line which causes all kinds of weird symptoms.
4) and make sure your carbs fuel bowl vent lines are open and not pinched or blocked. The bowls need to be vented to atmospheric pressure or the will not fill correctly
Finally, if the above 1 thru 4 is of no help...sigh, pull the carbs off and
5) Check your float heights. It sounds like your floats *could* be set too low.
A low fuel level in the float bowls will cause them to dry out at upper revs and the bike will go lean stutter and backfire....
Report back....Let us know what you find. Cheers! Pat
Wait, quick reset time: Did you get this thing recently and it has never worked properly, or did the bike used to work correctly and since awhile ago cease to do so?
Hey again, tripple checked float heights , double checked all hoses and lines, vacume advance is on #2 carb as per manual can swap for 3 if thats any help ? , unless the problem happens again i may have fixed it ?? re,routed coil wires ,seems it was arking out on fuel tank, , tank off ran perfect , tank fitted problem came back, sort and heatshrink wires , all good ? have had her for at least 7yrs , ,not used much lately dam it , thanks to all for the help , hope ive got it sortet
Quote from: Pat Conlon on June 28, 2011, 12:39:09 AM
... stick it in your mouth and suck, does it hold a vacuum?
Let's keep it PG here Colon!
Dan
Quote from: Dan Filetti on June 28, 2011, 11:16:14 AM
Let's keep it PG here Colon!
Dan
Ha...the Colon, yes... the organ that keeps your shit together.... :sarcastic:
Quote from: Pat Conlon on June 28, 2011, 12:12:28 PM
Quote from: Dan Filetti on June 28, 2011, 11:16:14 AM
Let's keep it PG here Colon!
Dan
Ha...the Colon, yes... the organ that keeps your shit together.... :sarcastic:
Ha!, I did not notice that. one little 'n' changes the meaning pretty dramatically!
hI, i RECENTLY HAD EXACTLY THE SAME ISSUE WITH MY 1100. tHE YAMAHA STORE, HAD THE BIKE FOR THREE WEEKS, THEY CHANGED ALL THE THINGS YOU SAID YOU CHANGED AS WELL AND IT NEVER ALTERED THE PROBLEM ONE BIT. uNTIL THE GUYS DICONNECTED THE WIRE THAT GOES FROM THE DASH TO THE CDI BOX. tHIS WIRE IS TELLING THE CDI TO SHUT THE SPARK TO CYL. 1 & 4, BECAUSE IT THINKS THE BIKE IS OVER REVVING. sOMEHOW THE TACHO IS SENDING A FAULTY SIGNAL TO THE CDI. oNCE THE GUYS CUT THIS WIRE, THE BIKE HAS BEHAVED PERFECTLY NOW FOR FOUR MONTHS. cHEERS FROM bENDER
Quote from: fj11.5 on June 28, 2011, 02:54:13 AM
Hey again, tripple checked float heights , double checked all hoses and lines, vacume advance is on #2 carb as per manual can swap for 3 if thats any help ? , unless the problem happens again i may have fixed it ?? re,routed coil wires ,seems it was arking out on fuel tank, , tank off ran perfect , tank fitted problem came back, sort and heatshrink wires , all good ? have had her for at least 7yrs , ,not used much lately dam it , thanks to all for the help , hope ive got it sortet
I've noted that if I'm not careful when putting the tank on, the fuel line can be pinched, reducing fuel flow. So what I do is lower it slowly while I'm on it's left side, (shifter side), using a screwdriver I locate the vacuum advance line and fuel line so they are not pinched, as sometimes, on my bike, they pinch each other off on the upper carb rack bracket. I've also shortened the two lines going down from the Y connector so the fuel line sits closer to the air box, which seems to help reduce the potential of further pinching. Of course your mileage may vary. The bottom line is to adjust fuel line lengths/positions to ensure they never get pinched.
Good Luck!
And...
Happy Holidays!
FJ Forever! :drinks:
JoBrCo
Mine does this but only when i try to break 100mph.
Probably cause im on stock jets.
I'd wager Pat is right on this one, fuel line is probably your culprit.
You can only rev as much fuel as you burn.
Quote from: theLeopard on January 03, 2015, 01:58:12 PM
Mine does this but only when i try to break 100mph.
Probably cause im on stock jets.
I'd wager Pat is right on this one, fuel line is probably your culprit.
You can only rev as much fuel as you burn.
Whoa Leopard , you should be able to hit 100mph easy with a stock jetted fj.
You may have a blocked fuel cap vent . There is a flapper valve in there that will cause fuel starvation after time. The fix is to take the fuel cap apart and remove the rubber flap.
Also if you use a magnetic tank bag it can block the gas cap vent and starve the carbs as well.
I'll put it on the list.
Is the flap valve replaceable? Ive really grown to love the singing.
Also, i occasionally use a magnetic tankbag, thanks for the tip. :hi: