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Discussion Starter #1
I've searched the forums but I haven't found a definitive answer.
I have a 2001 fi Bird that's running really rough low down and it's running incredibly rich with lots of black soot on the outlet of the cans, it also did about 45 miles to a tank of fuel, I've ordered an fpr and waiting for it to be delivered but I'm not convinced that's the problem as there seems to be no fuel in the vacuum hose when I remove it. The original exhaust system was in bad shape so I've replaced the entire system with oem downpipes including later model cans that have the cats in the link pipes, I've blocked the hole for the o2 sensor with the correct size bolt, after a run the exhausts are glowing red, is it possible that it's running so badly due to the cats in the pipes?
 

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I’m not a fuel injection operator. Interesting problem. The high fuel use/ poor mileage suggest a rich condition. The high exhaust temp suggest a lean condition, typically. The FPR if giving up lower fuel pressure would cause poor fuel atomization and a richer condition. One other item might be the wax unit which enables a rich mixture for easy start up. If it fails to close off the warm up circuit it might cause the bad mileage/rich mixture condition. Is there a aftermarket programmer in the mix, like a Dyno Jet PC-V?

The cats in the exhaust might might add some back pressure perhaps.

T.
 

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Someone had this problem before! The cats inthe pipes were causing obstruction and getting very hot!
I think he managed to get rid of the cats by some foul means and solved the problem.
Might not be the full cause of the OTT fuel consumption but can't help!
A search might find the origional post. I think it started by a worry about discoloration of the inlet pipes!
 

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If the bike is running rich then the cats will react by burning off the extra fuel and actually create the condition your stating. They typically run them leaner for this reason and why there were 02 sensors in the pipes to keep it lean but not going to lean. Your going to need to knock out the cat section or find some non cat cans.
 

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Steel rod and a lot of patience. You have to knock out the honeycomb matrix in the cat area. Or just get a set of non cat stock cans
 

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Another option . . . pick up an earlier set of OEM cans that were used w/o converters (prior to O2 sensors). Drill out the internal plugs (2 as I recall, that force exhaust through the multiple chambers within each can) with a 7/8" or 1" bit, thereby allowing a straight-through exhaust path. The resultant change in exhaust tone is subtle, slightly deeper and more mellow, yet still somewhat muffled; however, full throttle acceleration is another matter and tends to leave you prone to grinning. Another significant benefit is that the enhanced-flow cans run much cooler. True, there is actually little weight reduction, only a token amount; but efficiency has been arguably enhanced. And of course, the XX still appears to be completely stock. It just runs noticeably cooler, and sounds a bit better, IMHO. :cool:
 

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I've searched the forums but I haven't found a definitive answer.
I have a 2001 fi Bird that's running really rough low down and it's running incredibly rich with lots of black soot on the outlet of the cans, it also did about 45 miles to a tank of fuel, I've ordered an fpr and waiting for it to be delivered but I'm not convinced that's the problem as there seems to be no fuel in the vacuum hose when I remove it. The original exhaust system was in bad shape so I've replaced the entire system with oem downpipes including later model cans that have the cats in the link pipes, I've blocked the hole for the o2 sensor with the correct size bolt, after a run the exhausts are glowing red, is it possible that it's running so badly due to the cats in the pipes?
Yes- get rid of cat pipes
 

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Discussion Starter #11
Thank you for the replies so far, sorry but I didn't do an introduction, this is my third blackbird, I've had fireblades, zx10r ninjas, gsxr's, sv1000, xjr1300 but nothing beats the blackbird (when it's working properly). Better introduction to follow.
Bit of an update. Fitted new fpr and put on an old pair of battered venom pipes that I had lying around, they look shit but would do for testing purposes, problem still exists, did about 15 miles to £10 worth of fuel, it stumbles and hesitates low down the rev range and there's loads of black soot on the pipes. My next thought is testing the coolant temperature sensor to make sure the ecm is getting the correct signal to adjust the fueling, is this a possibility or am I way off?
 

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Chances are if it had a o2 sensor in it you'll need to put one back in and see how it reacts. Sounds like the system is looking for the 02 input to trim out excess fuel and without that it's running rich. The only other option would be to install a Power Commander and trim out fuel. Also pull the plugs and see if all or just one or 2 cylinders are running rich. If you have a IR temp gun you could shoot the primaries and see if there is a big temp difference as well. That low one is your rich running cylinder.
 

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Discussion Starter #13
It doesn't have the plug for an o2 sensor, all 4 plugs are black with soot. I measured the resistance of the temp sensor and it read 2.4k ohm at cold, my bike is a 2001 fi with an analogue dash, so should the temp sensor resistance be about 47k ohm, if so could that be an issue?
 

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Try orig fpr if you've got the latest fitted as newer is higher pressure. Also if your temp sensor is not reading correctly, could cause issue as may not see the bike is reaching temp and keep it in cold start mode. Ignore wax unit- it only gives higher tick over for when cold, worst it will cause is too low revs when cold or too high when hot.
 

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If it's wrong to what the manual states for your current ambient then yes. I'm not sure without looking which way it reads. IE cold = high resistance or low. See what the shop manual states. If it is off then yes it will raise cabin with the fueling. The BB's use a speed density program. And temp is a very important part of the algorithm used to calculate pulse duration.
 

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Discussion Starter #16
Thank you for the replies. Update, I put a 16k ohm resistor in line on the pink ecu feed wire and it runs much better, difficult to start cold though. I've ordered a replacement temp sensor with the higher resistance, I'll remove the resistor and see how it is with the new sensor fitted.
 
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