Is it a carb issue and how to fix it? - Page 4 - CBR Forum - Enthusiast forums for Honda CBR Owners

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

Is it a carb issue and how to fix it?

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  #31  
Old 05-16-2018, 05:35 AM
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On the 600F2, the floats are not adjustable...if there's a problem, they get replaced. Is that not the case with the 1000F?
 
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  #32  
Old 05-16-2018, 11:46 AM
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No, I don't think that's the case for the CBR1000FM as there's one of those metal tabs that sits onto the needle which can be slightly bent up/down which makes the float height adjustable - I think.
 
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  #33  
Old 05-18-2018, 01:58 AM
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For those of you who have been following/contributing to this thread (thanks) - and for everyone else - I've now tested my CBR1000FM out on the road a couple of times. It runs. In fact, if I roll open the throttle relatively slowly and close it equally slowly it runs very well. Really pleased with that, but, if I try to accelerate a bit harder or snap the throttle closed, sometimes (but not always) there's a significant hesitation followed by a backfire. In the past few days I took the carbs off and cleaned them (WITH THE EXCEPTION OF TWO OF THE PLUNGERS 'cos I simply couldn't undo the tops to access the diaphragms and withdraw the plungers). My question now is whether the current symptoms could be explained by my "incomplete carb clean". Could sticky plungers (for example) or any other carb component cause these symptoms? I know there are a few threads about similar problems on the forum but this is now a quite specific situation. Also, I'm conscious there are a few screws that could make it very difficult to get them off again (hence my original partial clean) so I'm looking for a little "guidance" before diving into something that could create a bigger problem rather than solve an intermittent hesitation I could probably live with if forced into it. If I do open up the carbs again, there's the unresolved issue of what is the correct setting for the float height - anyone have an answer to that too, please?
 
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  #34  
Old 05-18-2018, 02:31 AM
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Hi ,float height should be 9.5mm, slow jet 35, and main jet 120 , sizes changed on the 1992 bike
 
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  #35  
Old 05-18-2018, 03:40 AM
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Caberet - thanks very much for that info. I'm right the float height is taken simply by measuring it from the "lip" of the float bowl to the high point of the float? And just to check we are talking about a CBR1000FM. Thanks again.
 
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  #36  
Old 05-18-2018, 05:17 AM
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Yes thats right, info straight from Workshop manual , and crossed referenced with Autodata Technical Manual
 
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  #37  
Old 05-18-2018, 08:14 AM
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CaBeRet - thanks for the confirmation. Much appreciated.
 
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  #38  
Old 06-02-2018, 01:02 AM
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I've been out on the road a few times since last posting (and prior to re-opening the carbs) in order to try and "run the thing in". In fact, the intermittent hesitation/backfiring I was experiencing seems to have cleared itself as I've had nothing the past couple of times I've been out. I'm guessing there could have been a bit of crud stuck somewhere which has now been cleared out of the system. Maybe it shows that to have a little patience with carb related issues before diving in is not a bad thing.
 
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  #39  
Old 06-05-2018, 06:03 AM
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Default Loss of power+backfire when passing over a bump/hole

Latest "bug" in this thread.... There's no hesitation, misfiring, lack of power or anything else when running smooth and level at all speeds BUT, sometimes when I ride over a bump/hole in the road (especially at slow speed) there is a split-second total loss of power followed by a backfire and then the engine picks up again. It's as if something is "sticking" and the jolt from the bump releases it - or the jolt causes something to stick momentarily. I know the description sounds a little strange but that's how it is. I've been wondering whether a sticky plunger in one or more of the carbs could be the culprit. It's probably something I could live with if I absolutely had to, but I'm trying to decide whether I should take the carbs off (again) and before deciding, I'm looking for a bit of "collaboration" from the forum. Anyone experienced something similar?
 
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  #40  
Old 06-05-2018, 12:41 PM
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From what you describe, I wonder if it might be a loose wire or some other electrical

I'd make sure the battery terminals are tight, then move up the ignition circuit confirming there's good connections/continuity. Maybe check out the fuel pump (if so equipped)
 
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