first off, i would like to say that when it comes to fixing motorcycles i am a complete noob at it. but anyways, i have a 1997 honda cbr f3 and now when i use the choke to start the bike, it turns on fine and the rpms go up to like 2-3 grand. when i turn the choke off, the bike stays at 3 grand instead of coming back down to 1 grand. the bike only has 5200 miles and it has been running fine for the last month. the problem only started yesterday. someone suggested the carbs might need to be clean?? any advice would be appreciated, thanks in advance!

 

First off, where down south do you live and second that is really low miles on a 97. I would say it is the carbs. Know people with the same problem and that cleaning the carbs fixed it.

 

i live in orlando, fl. and i picked up the bike for 2000, the body is perfect. i guess i will need to clean out the carbs.

 

Have you tried adjusting your idle?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by marmaladeboy &raquo;</TD></TR><TR><TD CLASS="quote">Have you tried adjusting your idle?</TD></TR></TABLE>

we tried that, the bike was running perfect until a few days ago. it just feels like that the choke is stuck in the on position even when i turn it off. the idle stays at 3 and when i turn the choke off usually it goes back to 1 grand. also, when i was at a stoplight in first gear the bike just stall out while i had the clutch pressed in. i started the bike up again and it died. so i did it one more time and it was fine.

 

what happens when you blip the throttle? do the rpm's drop? are these stock CV type carbs?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MSchu &raquo;</TD></TR><TR><TD CLASS="quote">what happens when you blip the throttle? do the rpm's drop? are these stock CV type carbs?</TD></TR></TABLE>

the rpms go up when i rev and then sit back down at 3 grand. they are stock CV joints.

 

air/fuel screw... or idle. In addition there maybe an enrichment valve that operates off a diaphragm that may have a tear/split in it. Usually looks like a flat valve with a push/pull arm sticking out of the middle. But I vote air/fuel adjustment first

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MSchu &raquo;</TD></TR><TR><TD CLASS="quote">air/fuel screw... or idle. In addition there maybe an enrichment valve that operates off a diaphragm that may have a tear/split in it. Usually looks like a flat valve with a push/pull arm sticking out of the middle. But I vote air/fuel adjustment first </TD></TR></TABLE>

ok so i just tried to start the bike up without the choke and it wouldn't start. so i turn on the choke and start the bike again. the bike starts and within 5 seconds the rpms jump to 3 grand. i turned the choke off but the bike stays at 3 grand. i turn the idle down to about 1,200 rpms and let it run for 5 minutes. i come back outside and rev the bike a little and the rpms jumps right up at 4 grand. i turn the idle down once again to 1,200 rpms and try to rev it again and the bike just does the same thing by going to 4,000 rpm. im mechanically challenged so any help would be appreciated. ill probably take bike to a local shop and see what they say but i just want to know what u guys think.

 

Sounds like your throttle cable may be stuck. Or return spring.

 

you may also have a loose connection/cracked boot allow air into the charge. I would have to say unless you can physically see that the butterflies are not returning to full close, then a return spring it may not be. really it could be anything related to you butterflies not closing all the way, dirt in the carbs, a bad return spring, air getting into your enrichment circuit. when the bike is running @ 4krpms, can you physically close the butterfly assembly by hand at the carbs? if so then they are sticking open(which in one form or another is happening)and somethig is not allowing them to close to idle settings
Schu

 

don't know much about bike but from my car experience it almost sounds like a vacuum leak

and if the older CBR's are anything like my old yam theres plenty of places for a vacuum leak around the carbs where the carbs connect to the head

like MSchu says
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">a loose connection/cracked boot allow air into the charge.</TD></TR></TABLE>

all four of those boots on my yam were cracked