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post #1 of 9 Old 10-05-2019, 5:35 AM Thread Starter
 
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miss-fire

hi folks, my name is Tim, I have a '92 cbr900rrn streetfighter. I have had a misfire on it for over a year now. The Fuel tank had been sprayed and was full of overspray which was slowly peeling off. so, over the last 6 months, a new tank was fitted, fuel pump, lines, relay, rectifier, coils, plugs, filter(s), carbs re-jetted...standard jets, but to no avail. It was suggested that the floats could be worn on the pin, causing them to cockle and stick in corners or quick throttle opening... the times that it misses. Any ideas any one? I cant get new floats from anywhere in the world.. have bought from 4 companies only to be refunded as they are no longer available. any help much appreciated,
Tim
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post #2 of 9 Old 10-05-2019, 7:46 AM
 
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Re: miss-fire

are valve clearances and compression ok?
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post #3 of 9 Old 10-05-2019, 10:24 AM Thread Starter
 
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Re: miss-fire

yes, it runs great most of the time, like a swiss watch, but then plays up as though about to run out of fuel, would normally have you putting tap on reserve. does it when sat at around 5000 rpm misses a beat like fuel starvation....
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post #4 of 9 Old 10-05-2019, 1:52 PM
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Re: miss-fire

What are you running as far as aftermarket stuff, air filter, exhaust etc?

Sounds like a carb problem, either too rich or too lean, sound like it could be running too rich, does it smell of fuel when idling?

1993 CBR900 RR P
1994 CBR900 RR R Urban Tiger Project (now sold)
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post #5 of 9 Old 10-05-2019, 9:12 PM
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Re: miss-fire

Quote:
Originally Posted by tiimfu View Post
hi folks, my name is Tim, I have a '92 cbr900rrn streetfighter. I have had a misfire on it for over a year now. The Fuel tank had been sprayed and was full of overspray which was slowly peeling off. so, over the last 6 months, a new tank was fitted, fuel pump, lines, relay, rectifier, coils, plugs, filter(s), carbs re-jetted...standard jets, but to no avail. It was suggested that the floats could be worn on the pin, causing them to cockle and stick in corners or quick throttle opening... the times that it misses. Any ideas any one? I cant get new floats from anywhere in the world.. have bought from 4 companies only to be refunded as they are no longer available. any help much appreciated,
Tim
Please answer:

Did it happen out of nowhere?

Are you the original owner of it as a streetfighter?

What mods, if any?

Did you do a compression check? What were the numbers?

Is there a rats nest of wires near the airbox snorkels under the tank?

And I don't believe the floats are the issue. They are non adjustable, plastic and unless they have a hole in them they're good to go. Test float them in a container of fuel.
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post #6 of 9 Old 10-06-2019, 10:01 AM Thread Starter
 
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Re: miss-fire

ok, it has done it since I bought it as a Streetfighter, with tank full of overspray as I said. carbs have been off and cleaned 3 times and new jets and needles fitted, then balanced and set up. there are a few wires in front of air intake, but not enough to restrict air flow. original air box, filter and pipes down to collector, then a short stubby can, manufactured by a shop in Sheffield I believe. it particularly does it after full throttle opening, ie overtaking, shut off, open up again and feels and sounds like no fuel to the point it throws you up off the seat, not fun to ride
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post #7 of 9 Old 10-06-2019, 10:03 AM Thread Starter
 
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Re: miss-fire

floats have been tested in a bowl of fuel, no leak, but do feel very sloppy on the hinge pin, possible cockling and sticking??
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post #8 of 9 Old 10-09-2019, 8:19 PM
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Re: miss-fire

Quote:
Originally Posted by tiimfu View Post
yes, it runs great most of the time, like a swiss watch, but then plays up as though about to run out of fuel, would normally have you putting tap on reserve. does it when sat at around 5000 rpm misses a beat like fuel starvation....
I had similar problem '01- 929RR - turned out to be a cracked Throttle Position Switch (TPS) had to buy full set of throttle bodies from ebay as the TPS was not separately available from Honda.
Now my bike is running better than brand new - If not for a full face helmet I would have the proverbial "bugs in the teeth". I am sooo happy
Hope you find your solution.
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post #9 of 9 Old 10-09-2019, 10:15 PM
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Re: miss-fire

Thanks for the pic, and i'll offer you a guess. I'm going to say its a bit lean, based on the short muffler. I would offer you to raise the height of the needle with a washer or 2 if they aren't already adjustable.

Unlikely that the floats will get skewed enough to stick, they are quite sloppy on the rod.

Another thing to consider is a loose connection that vibrates out at a specific RPM.

What are the size of the jets that are in there? Also, does it still have the fuel pump?
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