93 cbr1000f hard start wont idle
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From: Lincoln, NE
93 cbr1000f hard start wont idle
just got everything back together (carbs, plugs, etc) and for the first time since i bought this bike it finally fired. will only start on choke, and with a little acceleration only then can i turn choke off, but no matter what i do it will not stay running. starts really hard. please tell me seafoam....please lol
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From: Northern Michigan
Seafoam...
but seriously, seafoam will probably not be the answer. From the sounds of it, you may just not have the idle set high enough. Im not sure on that model, but there should be a either a screw on the rack that prevents the carbs from closing all the way, or there is cable with a thumbscrew on the side of the bike that attaches to the rack. If the idle is set too low, it will not idle and will require a little bit of throttle to stay running.
However, it could be something more than just that. But thats the first thing I would check. You could have a vacuum leak at the carb base. You could have the carbs so out of sync it won't run in the lower rpms. It sounds like you may not know the history of the bike very well, so it could be any number of things.
But, you can keep posting back the things you have tried and surely someone here will offer other things to check.
but seriously, seafoam will probably not be the answer. From the sounds of it, you may just not have the idle set high enough. Im not sure on that model, but there should be a either a screw on the rack that prevents the carbs from closing all the way, or there is cable with a thumbscrew on the side of the bike that attaches to the rack. If the idle is set too low, it will not idle and will require a little bit of throttle to stay running.
However, it could be something more than just that. But thats the first thing I would check. You could have a vacuum leak at the carb base. You could have the carbs so out of sync it won't run in the lower rpms. It sounds like you may not know the history of the bike very well, so it could be any number of things.
But, you can keep posting back the things you have tried and surely someone here will offer other things to check.
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From: Lincoln, NE
thumbscrew yes. was afraid to tinker with it so soon before getting some input. i imagine clockwise is to raise? i will try that first. carbs may have never been sync'd as far as i know. bike sat for damn near a year i have been told and dumped on left side. by the amount of rust i found in the fuel tank i wouldnt be surprised if it sat longer. float bowls all looked fairly clean, spark plugs looked brand new still, but i was too nervous to take apart the diaphrams on the carbs to inspect. however.....it started...finally....will post upon it running idle, then may tackle syncing if im not satisfied. just want to ride the damn thing. first ever bike. got it for $500.00. oh but to hear it fire and rev........oh my.....
thumb screw had no effect as far as i could tell, no matter which way it was turned. upon inspection it appeared to be closed all the way, or screwed in completely. with one hand on the throttle keeping it from dying, i slowly rotated thumbscrew with no success. bike still goes kaput after letting go of throttle. if it were a vacuum leak, would a hissing sound be obvious? and help me understand why it will only start in the choke position? im learning as i go so bear with me....ugh..i know...new guys...lol
thumb screw had no effect as far as i could tell, no matter which way it was turned. upon inspection it appeared to be closed all the way, or screwed in completely. with one hand on the throttle keeping it from dying, i slowly rotated thumbscrew with no success. bike still goes kaput after letting go of throttle. if it were a vacuum leak, would a hissing sound be obvious? and help me understand why it will only start in the choke position? im learning as i go so bear with me....ugh..i know...new guys...lol
Last edited by Sprock; Jul 17, 2011 at 02:55 PM.
Administrator, MVN / ROTM NOV 2012
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From: Republic of Boon Island
Are all the rubber caps on the carb sync ports ?
AND hell yeah you want to run SeaFoam through it if it's been sitting on it's azz for a year
If you are seeing rust it may be a good idea to go and install an inline filter as it may save
repetitive carb cleanings !
Moved into Hurricane Section for a little more focused exposure , ideas and answers
AND hell yeah you want to run SeaFoam through it if it's been sitting on it's azz for a year
If you are seeing rust it may be a good idea to go and install an inline filter as it may save
repetitive carb cleanings !
Moved into Hurricane Section for a little more focused exposure , ideas and answers
Last edited by Sprock; Jul 17, 2011 at 03:00 PM.
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From: Lincoln, NE
thx for moving btw.
as a complete newbee at motorcycle repair, well cycles in general, ill have to look up what u mean by rubber caps cause im not sure what u are referring to, sry. when i had the carbs off, i had a mechanic look at the carb and all he said was dont do anything else to it after cleaning the bowls....just put it back in and fire her up. as far as the jets are concerned, i did not remove them, but looking back now i should have just to be safe. suppose ur going to tell me i should have lol.
as far as the rust...the tank was indeed pitiful. with the cunning use of bb's and some nuts and bolts i was able to remove most of the corrosion, then hit it with a good warm soapy hpressure wash, followed by a good drying with a compressor. an inline filter is a good idea, so thx for that.
crap...now the petcock is leaking fuel at the rivoted flange. just a drip every now and then but still....ugh!
as a complete newbee at motorcycle repair, well cycles in general, ill have to look up what u mean by rubber caps cause im not sure what u are referring to, sry. when i had the carbs off, i had a mechanic look at the carb and all he said was dont do anything else to it after cleaning the bowls....just put it back in and fire her up. as far as the jets are concerned, i did not remove them, but looking back now i should have just to be safe. suppose ur going to tell me i should have lol.
as far as the rust...the tank was indeed pitiful. with the cunning use of bb's and some nuts and bolts i was able to remove most of the corrosion, then hit it with a good warm soapy hpressure wash, followed by a good drying with a compressor. an inline filter is a good idea, so thx for that.
crap...now the petcock is leaking fuel at the rivoted flange. just a drip every now and then but still....ugh!
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From: Lincoln, NE
on my carb there is only one rubber cap that i can see. its rather obvious. on top. anyway...i took out the carb again (got it down to 7 minutes!) and will clean bowls and jets thoroughly, inspect diaphragms, reinstall and try again.
if anyone....and i mean anyone....has further advice.....
if anyone....and i mean anyone....has further advice.....
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Joined: Oct 2006
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From: Queensland, Australia
Check the fuel flow at the carbies. Take the main fuel line off at the carbs. There's a thin rubber line running from the vacuum operated petcock. Disconnect the other end and suck on it to supply the vacuum. You should hear a small 'click'. If no fuel comes out of the main fuel line, then you've got crap in the petcock stopping it opening.
+1 on the inline filter, but if the tank was that bad, then I'd say the petcock could get crap in it for a while.
It really sounds like fuel starvation to me mate so try to see if you've got a good flow.
The other really basic thing that can cause grief with a bike left for a while is the tank vent. When it's about to cut out, open the tank and listen for a whoosh of air rushing in.
Give these couple of simple (and free!) things a burl and get back to us.
+1 on the inline filter, but if the tank was that bad, then I'd say the petcock could get crap in it for a while.
It really sounds like fuel starvation to me mate so try to see if you've got a good flow.
The other really basic thing that can cause grief with a bike left for a while is the tank vent. When it's about to cut out, open the tank and listen for a whoosh of air rushing in.
Give these couple of simple (and free!) things a burl and get back to us.
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From: Lincoln, NE
petcock seems to be functioning normally as far as i can tell. was able to prime fuel line with little resistance. heard clicking sound as u referred to as well. i cant really test for air starvation at the moment since i have the carb off but vent tube on tank is clear (1200lb pressure wash made sure of that!lol)
Since it would only start in the choke position what else could that mean? guess ill have more info after cleaning again and reinstalling. may have to replace petcock anyway since its leaking fuel at the diaphragm. has anyone ever drilled out the rivots to repair? thx for all info so far.....
Since it would only start in the choke position what else could that mean? guess ill have more info after cleaning again and reinstalling. may have to replace petcock anyway since its leaking fuel at the diaphragm. has anyone ever drilled out the rivots to repair? thx for all info so far.....
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Joined: Oct 2006
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From: Queensland, Australia
From cold, mine needs full choke to start then I can turn it completely off pretty soon.
When it runs, once the choke is off, does it run evenly and cleanly even if it's not for very long? How long does it run for?
Sorry for all the questions to your question mate, but we need more clues. Press on with it and somebody will come up with the solution soon enough. When it's sorted, you'll be well rewarded with a great bike!
Can't picture the rivets and just off to bed. I didn't have to re-build the actual tap part, just the vacuum valve. I got a kit from a Honda dealer for not much $.
If it runs cleanly then my money's still on fuel starvation. If it stutters and farts, barely running, then I'd be thinking carbs well out of balance, incorrect valve timing etc. Pull the plugs and have a look to see if they're all the same. Put a bit of spit on your finger and (very quickly!!) touch the headers one at a time to make sure all four are firing.
Hopefully it's just something daft.
When it runs, once the choke is off, does it run evenly and cleanly even if it's not for very long? How long does it run for?
Sorry for all the questions to your question mate, but we need more clues. Press on with it and somebody will come up with the solution soon enough. When it's sorted, you'll be well rewarded with a great bike!
Can't picture the rivets and just off to bed. I didn't have to re-build the actual tap part, just the vacuum valve. I got a kit from a Honda dealer for not much $.
If it runs cleanly then my money's still on fuel starvation. If it stutters and farts, barely running, then I'd be thinking carbs well out of balance, incorrect valve timing etc. Pull the plugs and have a look to see if they're all the same. Put a bit of spit on your finger and (very quickly!!) touch the headers one at a time to make sure all four are firing.
Hopefully it's just something daft.
