Is it a carb issue and how to fix it? - Page 2 - 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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  #11  
Old 05-08-2018, 09:15 PM
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Originally Posted by hamlin6 View Post
Gronk is wise, (except his choice of NFL teams),
You had to rub that in lol!!!
 
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  #12  
Old 05-08-2018, 09:18 PM
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:-) I am a Horse Shoe Head fan so I have no room to talk.
 
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  #13  
Old 05-09-2018, 03:36 AM
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Thought I'd give all you guys providing me with technical advice (and some moral support) with an update on where I am - mainly with my thinking. I contacted Seafoam technical support about my temptation to try a first step of running on a 50:50 mix then soaking for 24 hours. They said they would recommend that as it may minimise possible nugatory effort. They also said, if after an initial 24 hour soak there is some, but not enough improvement, another similar soak might solve the problem completely. {I know, I can hear you say ...but they would say that wouldn't they, but I feel I have little to lose with that as a first step.} I even asked Seafoam whether it would be OK to soak the jets etc in neat Seafoam if I am eventually "forced" to remove them and they confirmed that would be OK too. Unfortunately, 'cos I'm in France (not US or UK) Seafoam is not available in local stores hence just getting hold of the Seafoam through www (from Germany!) has taken a week so far - it arrived this morning. Despite planning on an initial Seafoam soak, I've already removed the fuel tank in anticipation of having to anyway. That led me to notice some light rusting inside the tank. So I'm now thinking of a vinegar/salt rust removal process although as it is only light surface rusting and not all over, I'm not sure it's absolutely necessary - what do you think guys? Also, if I do go ahead with the vinegar/salt treatment, do I need to remove the petcock and fuel level sensor, or would it be OK to leave in place to "block those holes" and reduce the chance of any collateral damage when unscrewing things? I've asked a separate question on that elsewhere in the forum. So my first step is now clear, and I'm psychologically prepared for the possible additional step of removing and cleaning the carbs myself. I've already asked a garage over here in France roughly how much they would charge to clean the carbs and it's around €650 - roughly $1000/£600 (crazy but true) - so I'd be thinking pretty hard whether my otherwise gleaming CBR1000F would ever get back on the road if it came to that. Anyway, I'm going to try that Seafoam thing now and I'll update you when it's done. Fingers crossed etc.
 
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  #14  
Old 05-09-2018, 03:52 AM
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If you're going to pull the jets, soak them in carb cleaner, not seafoam. They are brass.

I doubt it will help though - once those idle jets get clogged, you have to physically clear them. The hole in them is beyond tiny.
 
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  #15  
Old 05-09-2018, 05:39 AM
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Seafoam's now in. And now for the 24 hr wait. Rockpool's tip on spraying water onto the exhaust downpipes to identify the problem ones is a great one, but it does need to be done before the engine gets too warm otherwise all the downpipes get pretty much equally hot. In fact, it's cylinders 1 and 2 that seem to be the problem. As they are on different electrical circuits, that probably confirms it's not an electrical issue(?). Just want to clarify that the actual problem is i) can't take off the choke without the engine dying even when warm, AND ii) the engine wants to die when I try to open or just blip the throttle......Could this simply mean that both idle jets and main jets are blocked or would the idle jets only being blocked cause the same symptoms?
Also, Rockpool's point about having to "physically" clean the jets rather than rely on carb cleaner (not Seafoam) is noted. I'll remember that if I eventually find myself at that point.
 
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  #16  
Old 05-09-2018, 01:19 PM
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All your symptoms match mine.

Lumpy idle, won't run without the choke on, poor throttle, bogging down when blipping until it's really warmed up etc.

Those idle jets are the bane of my life - so much so I have the 5 tools needed to do the whole job in a separate drawer in my garage, and I changed all the carb bowl screws to allen bolts so I can use a power screwdriver with pre-set torque to remove and replace them quickly.

I even bought a second set of jets so I can do the swap quicker and get back on the road ;-)
 
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  #17  
Old 05-10-2018, 03:06 AM
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I even bought a second set of jets so I can do the swap quicker and get back on the road

Sounds like you get really shiitty fuel to have that many problems, maybe you should try a secondary fuel filter.
 
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  #18  
Old 05-10-2018, 03:28 AM
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I have no idea - the first 20 years I didn't have to touch them at all. You are right though that a paper cartridge filter wouldn't hurt.
 
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  #19  
Old 05-10-2018, 12:46 PM
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After 24 hours soaking in 50:50 Seafoam, there's been a tiny improvement but nowhere near enough so I've bitten the bullet to start dismounting/cleaning the carbs. Tank is off, and all the pipework/breathers/cables are disconnected and the airbox is disconnected too. HOWEVER, I've now got to the point of trying to actually get the carbs out - and first snag - I can't get them to budge much at all. I've loosened the 4 band clamps (out of 8) on the carb side of the boot connecting them to the engine but the carb block will move only 2mm. After 27 years in the same position I feared this would be an issue. I've wriggled, jiggled, yanked and ?anked the things around, and used various pieces of wood and metal to try and prise the carbs out of the boots (paying due care not to damage linkages etc) but nothing. I've even put a few drops of WD40 in there but that's made no difference either. After 2.5 hours of exercise I've exhausted my own ideas for the day, so has anyone got anything to suggest. Rockpool - I guess when you take them off as often as you do it's not a problem, but is there a particular "technique" that works best? I don't really want to fail at the first hurdle.
 
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  #20  
Old 05-10-2018, 01:36 PM
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lol - you are right, the insides of my bands are lubricated with lithium grease to make it easy.

The trick is to straddle the bike, grab the outside carbs and rotate the whole assembly up and towards the front of the bike. Installation is the same, get the top in, then push down and forwards.

You won't be able to pull the carbs back off the sleeves, you have to rotate them - the sleeve sits in a grove so has to be pushed in (and pulled off) at an angle.

Make sure the carb side of the head sleeves is really loose - you want to leave the sleeves on the head so don't touch that side.

And also take note that the bands fit into indices on the tubes - they are not smooth, they have notches etc to stop the bands from rotating when you're tightening them up.

BTW - you don't need to remove the cables, you can simply rotate the whole assembly while they are still connected - the carb stack will sit nicely upside down on top of the head. You'll find there are a couple of vent pipes which simply sit behind the battery box (and are clipped into a bendable band on the same bolt as the airbox fitting).
 
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