CBR 1000F "Hurricane" 1987-1996 CBR 1000F

revs slow to drop to tickover

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Old 08-23-2019, 09:48 AM
Lynch's Avatar
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Default revs slow to drop to tickover

My 1988 CBR1000F. has had a full restoration after many years off the road. The engine has had a new cam chain, and alternator tensioner, and a new starter damper.
The carbs were ultrasonically cleaned and balanced with my vacuum gauges . The airbox was replaced with one with good rubbers. However , it runs really well - right up to the red line and is a good starter, although it takes a minute to run on all cylinders , but the idle is not very consistent. It also takes a second or three to drop to idle at a junction or lights.
The idle seems to need adjustment as it warms up. I'm wondering if the coils could cause this effect.
Any advice gratefully received

Painted by my self - looks ok from 2-3 meters !!!
 
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Old 08-23-2019, 01:10 PM
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If it takes that long to drop to idle, I'd probably confirm that the throttle cable is good. If it's sticking it would cause all sorts of bad behavior

I'd also take a second look at the carb boots and make sure that there isn't any gaps or cracks in the boots

It could be a bad or intermittent spark, or even a bad battery. It may also be lean or rich, so if it's convenient it may be worth looking at the spark plugs or looking at the idle drop procedure to make sure they are tuned properly, but I'd start with the easy stuff first

Paint looks really good btw. Nice job bringing her back to life
 
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Old 08-23-2019, 02:14 PM
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Originally Posted by Lynch
Painted by my self - looks ok from 2-3 meters !!!
You paint like me.

I am also thinking maybe a vacuum leak somewhere.
 
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Old 08-23-2019, 02:32 PM
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that was what I was thinking - there was a Scott oiler fitted some time in the past, and they used one vacuum take off from carb 1.
I cut and sealed the vacuum pipe, 2 cm from the carb and sealed it . Maybe that is leaking.
I will check it out.
 
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