Author Topic: 73 CB350F, failed emissions; CO2 only (Read 6837 times)

rboe · « **on:** June 20, 2012, 05:07:57 PM »

Just did the emissions test here in Phx; Hydrocarbons read out 1202 (standard is 1800) but CO2 was 8.05, need to hit 5.5.

Carbs had new stock jets installed (but the needles were not touched); have no idea what size stock is. Everything else is stock.

Have not touched the plugs or points or checked the timing.

Fresh 91oct gas with maybe a 1/4cup of sea foam to a gallon of gas. Seems to run pretty good, idles fine, starts fine (need to pull the plugs and look at them again but they had the light brown coating last time I checked).

Probably need to check the floats as I didn't touch them when they were out.

Everything points to taking the carb cluster out again (inset whiny noises here

) and I'm squirming like mad to avoid that.

Any hints?

Greggo · « **Reply #1 on:** June 20, 2012, 05:09:17 PM »

You have to smog that???

LesterPiglet · « **Reply #2 on:** June 20, 2012, 05:13:06 PM »

Maybe the Seafoam is the culprit.

HondaMan · « **Reply #3 on:** June 20, 2012, 05:18:22 PM »

Try turning the air screws inward a little, like 1/8 to 1/4 turn or so. It will make it cold-blooded, but it should idle OK once warmed up.

rboe · « **Reply #4 on:** June 20, 2012, 05:41:29 PM »

Woot! Thank you sir. I get one free do-over.

Yes, in Phoenix we have to have them tested. Waiting for the epa to give us the exception. Testing is cheap, and in cases like mine, discover problems that are a bit subtle to pick up on otherwise. I really thought it was good to go. No fumes that I could detect, ran fine (although a bit gutless but that seems to be the nature of the beast, no threat of your arms being stretched with this little beast).

But we never had emissions back in Minnesota so I have no skill set what so ever with carbs and emissions. With modern cars it's pretty much a pass if no red light on the dash. On board computers handle everything. If not, you wiggle your nose (aka pull out the plastic) to have it fixed.

Gordon · « **Reply #5 on:** June 20, 2012, 05:48:42 PM »

Take a look at these two threads:

http://forums.sohc4.net/index.php?topic=102903.0

http://forums.sohc4.net/index.php?topic=104420.0;all

camelman · « **Reply #6 on:** June 20, 2012, 06:00:44 PM »

You probably shot yourself in the foot with the high octane gas. Your engine will run best and create the most power with the lowest octane possible. Higher octane than necessary will slow down your burn speed which will result in less than optimal cylinder pressures. Combined with potentially weak or poorly timed spark the emissions will be off. Also, sea foam is a heavier oil than gasoline, do it will emit a higher mass fraction of carbon.

Try this. Fresh tank of 87 without sea foam. Check your timing and point gaps and verify your plugs and plug caps are good. Adjust your cam chain, and possibly your valves. Then try it again.

rboe · « **Reply #7 on:** June 20, 2012, 06:22:26 PM »

More good stuff! Thanks folks!

rboe · « **Reply #8 on:** June 20, 2012, 06:29:43 PM »

My air screws are about one turn out. Twisted them in about 1/8th turn. Need to check the floats now.

Bankerdanny · « **Reply #9 on:** June 20, 2012, 06:58:33 PM »

Really? How can they possibly justify testing a vehicle that was never subject to any emissions laws?

tomkimberly · « **Reply #10 on:** June 20, 2012, 07:13:26 PM »

That sucks.

http://www.azdeq.gov/environ/air/vei/motor.html

Tom

Retro Rocket · « **Reply #11 on:** June 20, 2012, 07:15:19 PM »

Quote from: Bankerdanny on June 20, 2012, 06:58:33 PM

Really? How can they possibly justify testing a vehicle that was never subject to any emissions laws?

Yeah, thats a joke...

rboe · « **Reply #12 on:** June 20, 2012, 08:28:00 PM »

It is what it is. At some point common sense will prevail. In the mean time one must persevere.

scottly · « **Reply #13 on:** June 20, 2012, 08:38:08 PM »

In CA, in the early '70s, they passed a retro-active smog law, that affected cars back into the mid-fifty's, if I recall correctly. It involved preventing vacuum timing advance from operating until the motor was fully warmed up. There were great debates about how it wasn't fair to require a costly retro-fit, so there was a stipulation that less expensive options be available. The expensive kits had a thermostatic valve spliced into the upper radiator hose, and the cheap kits consisted of a plug for the vacuum source port, and a decal plastered to the speedometer face that warned that driving for extended periods above 55 MPH may result in engine damage. It was a joke, and was repealed after one or two years, but it caused more harm than good.
Speaking of which, has anyone been in PHX long enough to remember the "smog dogs"? They were road-side "sniffers" that were supposed to sample tail-pipe emissions of cars driving by. The ADOT ditched them when it came out that the gasoline fueled generators that powered them were spewing more pollutants than the cars.

rboe · « **Reply #14 on:** June 20, 2012, 09:06:49 PM »

Have not seen the smog dogs in a while.

HondaMan · « **Reply #15 on:** June 20, 2012, 10:54:31 PM »

According to the Honda Shop Manual of the 350f/400F combined variety...the air screw on the 350F should be at 7/8 turn, +/-3/8 turn. This is comparable to others like it: if you go inward from the 7/8 setting, up to 3/8 turn, it leans out the mix until it reaches about 1/2 turn inward: then it start cutting off the air, too, and the mix can get clumpy and "look" rich in a smog test (too much CO). When the screw is turned outward from the 7/8 setting, up to 3/8 turn, it gets richer until you reach about 1/2 turn out, then it stops lifting fuel and it gets thin and uneven, fouling plugs and again causing too much CO. It's all a little confusing, I know...but suffice to say, stay within the 4/8 to 1-2/8 turn range, or you'll get real mixed up (so to speak

).

This small adjustment range (on all of these types of carbs) is due to the short nature of the vacuum pulse at low engine speeds. The useable range of the screw is limited due to the dynamics of the moving fluid column that is the tiny emulsifier tube of the idle jet. This is why these bikes are all to 'touchy' about the size of the idle jets, with a single-digit number change causing real headaches sometimes!

So, if the mix is still too rich (too much CO) it may be possible to drop down on the idle jet size one step (this is usually a 2 number), to lean it out within the same 7/8 +/-3/8 range. This will also lower CO.

rboe · « **Reply #16 on:** June 21, 2012, 04:14:29 PM »

Thank you Sir! Life has interrupted me so I may not be able to get back to the testing until next week. I'll keep you posted though.

JamesM · « **Reply #17 on:** June 21, 2012, 05:08:41 PM »

My girlfriend and I are moving to the Phoenix area this winter, this is not news I wanted to hear.

scottly · « **Reply #18 on:** June 21, 2012, 07:29:36 PM »

Quote from: rboe on June 21, 2012, 04:14:29 PM

Thank you Sir! Life has interrupted me so I may not be able to get back to the testing until next week. I'll keep you posted though.

In the meantime, you may want to run the tank of Sea-foam mix through the bike, or at least siphon it out and replace it with fresh gas before the test; who knows how Sea-foam affects sniffer readings? (In my part of AZ, we don't have to suffer with the indignity of having probes inserted into our tail-pipes..

)

rboe · « **Reply #19 on:** June 21, 2012, 07:38:59 PM »

Gas has been drained and put in the car.

New Regular gas put in the bike and run down the street. I need to run her a bit more to clear the floats out of the old stuff just to be safe. I might be able to run her through testing tomorrow. Puppy has to go the vet, kinda depends on how long that takes.

James; lot's of old bikes running down here with plates. If your bike is in good running order it should not be a problem. Who knows, maybe by then you won't have to. I would not hold your breath though.

burgundysquare · « **Reply #20 on:** June 22, 2012, 10:26:41 AM »

We dont even have to smog them in California, thats strange you would have to elsewhere.

rboe · « **Reply #21 on:** June 22, 2012, 01:38:05 PM »

I had a few minutes before the vet visit so I ran her through testing again. Did worse this time. 9.02 vs 8.05. Maybe I should have backed the air screw OUT a wee bit?

Going to run by the honda dealer to see if they have a tester or this will get expensive, making tweaks, testing, failing - repeat.

Thought I was on the right track as she seemed to need more choke on start up.

I keep telling myself that old bikes are more fun.......

rboe · « **Reply #22 on:** June 22, 2012, 03:41:42 PM »

Stopped by the dealer and they will let me use their sniffer free of charge but they won't work on the bike (for some reason that was a relief).

Once I pull the carbs and set the floats (may be able to do that while they are in the bike, we shall see) I'll be in a better position to take them up on the offer.

lucky · « **Reply #23 on:** June 22, 2012, 03:57:06 PM »

To pass the emissions test just change the oil right before you go and the plugs.
The test measures the burning oil. If the oil is clean you will pass.

Its that simple.

rboe · « **Reply #24 on:** June 22, 2012, 04:02:31 PM »

Oil is new, plugs are not. I was under the impression that this was not an ignition issue but an air ratio problem and that plugs would help (unless they showed signs of excessive carbon etc.

In that case I should consider changing the points too.

News:

Author Topic: 73 CB350F, failed emissions; CO2 only (Read 6837 times)