87 CBR 600 emissions confusion
#1
11-30-2012, 07:18 PM
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87 CBR 600 emissions confusion
So originally i ran my bike through emissions with HC being at about 2300, After cleaning and bench syncing the carbs i came in at about 2600. took carbs apart again and found my air cut-off valves to be pretty much destroyed. Replaced them and adjusted my air/fuel mixture screws to 1.5 turns out to try and lean it out a bit. It jumped up to about 3300 for HC and down to .25 for CO. Turned the fuel mix screws out to about 2.5 turns and it got worse at about 3400. What im trying to figure out is what the hell should i do next.... I replaced my spark plugs, oil, air cuts, cleaned the carbs. Only next thing i can think of is check the valve lash.... any ideas would be very appreciated. Thanks guys in advance
#2
12-01-2012, 10:41 AM
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How does the bike run in general? High HC's are a result of incomplete combustion typically from worn/malfunctioning ignition system components, over advanced timing, or major engine mechanical issues such as low compression.
If your CO is under .5% it's definitely not being caused by an excessively rich condition.
It's hard to diagnose something like this over the net, but just looking at the info here I would be looking for a misfire assuming the engine compression is good across all 4 cyl's. Also might want to check the timing to make sure someone hasn't put a big ignition advance sprocket in there. Valve lash is also a possible contributor and should be checked as well.
Is the engine getting up to the correct operating temperature?
If your CO is under .5% it's definitely not being caused by an excessively rich condition.
It's hard to diagnose something like this over the net, but just looking at the info here I would be looking for a misfire assuming the engine compression is good across all 4 cyl's. Also might want to check the timing to make sure someone hasn't put a big ignition advance sprocket in there. Valve lash is also a possible contributor and should be checked as well.
Is the engine getting up to the correct operating temperature?
#3
12-01-2012, 10:50 AM
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yeah its a good 20 minute ride at about 50 to the emissions center. i havent checked the compression yet but i was concerned with the timing too since just about everytime i blip the throttle i get the chain rattle pretty bad. But thats the thing is it rides great i mean it hauls like it should so im kinda stumped.... ill pull the covers and check the "timing chain" also. And can i adjust the valves on it without the adjuster tool called for in the manual and just use a good ole ratchet. thanks for the reply
#4
12-01-2012, 08:16 PM
Where do you live that requires an emissions test on a 25 year old motorcycle? California didn't even have the stricter emissions standards on bikes until 1988 I thought. Also, at least in the states I have lived, motorcycles go exempt after a certain age, usually 20 years old. The current state i live in doesn't have emissions testing anywhere except in the Salt Lake valley. The other 90% of the state does not have to deal with it.
Found the main post on it from the EPA:
Since you have a 1987 it does not have to meet the 1988 or later emissions levels. Also:
from http://dmv.ca.gov/vr/smogfaq.htm#BM2536
Found the main post on it from the EPA:
2. Regulation by the California Air Resources Board Motorcycle emission standards in California were originally identical to the federal standards that applied to the 1978 through 1981 model years. The definitions of motorcycle classes used by California continue to be identical to the federal definitions. However, California has revised their standards several times to bring them to their current levels. In 1982 the standards were modified to reduce the HC standard from 5.0 g/km to 1.0 or 1.4 g/km, depending upon engine displacement. California adopted an evaporative emission standard of 2.0 g/test for 1983 and later model year motorcycles. In 1984 California amended the regulations for 1988 and later model year motorcycles to further lower emission standards and provide additional compliance flexibility to manufacturers. The 1988 and later standards could be met on a corporate-average basis, and the larger (Class III) bikes (280 cc and above) were split into two separate categories: 280 cc to 699 cc and 700 cc and greater. These are the standards being met in California today. Like the federal standards, there are no currently applicable NOX standards for highway motorcycles in California. Under the corporate-averaging scheme, no individual engine family is allowed to exceed a cap of 2.5 g/km. Like the federal program, California also prohibits crankcase emissions.
Table IV-3.--Current California Highway Motorcycle Exhaust Emission Standards ------------------------------------------------------------------------
Engine size (cc) HC (g/km) CO (g/km)
------------------------------------------------------------------------
280-699........................................ 1.0 12.0
Table IV-3.--Current California Highway Motorcycle Exhaust Emission Standards ------------------------------------------------------------------------
Engine size (cc) HC (g/km) CO (g/km)
------------------------------------------------------------------------
280-699........................................ 1.0 12.0
Does my vehicle qualify for a smog exemption?
Smog inspections are required unless your vehicle is:
Hybrid
Gasoline powered 1975 year model or older
Diesel powered 1997 year model and older or with a Gross Vehicle Weight rating (GVWR) of more than 14,000 lbs
Electric
Natural gas powered with a GVWR rating of more than 14,000 lbs.
Motorcycle
Trailer
Smog inspections are required unless your vehicle is:
Hybrid
Gasoline powered 1975 year model or older
Diesel powered 1997 year model and older or with a Gross Vehicle Weight rating (GVWR) of more than 14,000 lbs
Electric
Natural gas powered with a GVWR rating of more than 14,000 lbs.
Motorcycle
Trailer
Last edited by drakito; 12-01-2012 at 08:29 PM.
#5
12-03-2012, 08:31 PM
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yeah its a good 20 minute ride at about 50 to the emissions center. i havent checked the compression yet but i was concerned with the timing too since just about everytime i blip the throttle i get the chain rattle pretty bad. But thats the thing is it rides great i mean it hauls like it should so im kinda stumped.... ill pull the covers and check the "timing chain" also. And can i adjust the valves on it without the adjuster tool called for in the manual and just use a good ole ratchet. thanks for the reply
It could have a vacuum leak which would cause a lean misfire (high hc's) at idle, but wouldn't really be noticeable under acceleration. What were the other % numbers for CO on the other tests?
edit: Have the carbs been synced since they were last taken out & repaired?
Last edited by TahoeRider; 12-03-2012 at 08:55 PM.
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12-03-2012, 08:37 PM
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#7
12-13-2012, 08:09 PM
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Hey the last test i went and did my CO number was .25. That was after replacing my aircut valves with the air/fuel mixtures set at about 3 turns out. I havent had it tested since but i have gone through and adjust my valves. Set my intakes to about .017mm and my exhausts to about .021mm if i remember right. One thing i did notice though as i was going through them with the manual i downloaded from the link on here is that my intake timing gear was off about a tooth. It says in the manual that the marks on the sprockets are supposed to be level with the deck of the head but my intake sprocket was about a tooth above like i said. I corrected that and was putting my valve cover back on and when i wasputting my ratchet on the last bolt i barely turned it and snap it went. So now i have to get that stud out and get a new bolt than throw it all back together and try to fire it up after correcting the sprocket.
Anyone think that the one tooth on the intake could cause the high HC. I mean when i think about it if the intake is off than that could cause the exhaust to have excessive fuel depending on which part of the cycle it was on. Idk though let me know what you guys think.
Anyone think that the one tooth on the intake could cause the high HC. I mean when i think about it if the intake is off than that could cause the exhaust to have excessive fuel depending on which part of the cycle it was on. Idk though let me know what you guys think.
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