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Discussion Starter · #1 ·
Not like "HOLY COW THAT IS SMOKING!" but more like... "Did you just blow a tad bit of dust off the ground?" kinda smoke.

Only when she's cold and only when you twist the throttle to crack her a bit. To tell you the truth it's barely noticeable at all - but after a few minutes when she's warm - no more.

Not at idle.
Not when cracking at idle.
Not under a load.

I didn't notice this until after I had my bike tuned on a Dyno. I was running extremely lean on the low-end (16/15:1) - but now I'm sitting at 14:1 while under the power-band and 13:1 while in the power band.

So technically at idle I'm at 14:1. Now... could this just be carbon build-up? A friend of mine told me to throw some STABIL or Sea Foam into my next tank to help clean everything out - or just run it hard on the expressway. He says he had the same issue with his (V-Rod) when he had work done to it and tuned - he said it went away after a few hundred miles.

Carbon build up? Can't be burning oil - it would smoke all the time - especially when hot and under a load - and more noticeable than just "i can barely see it".

I have no performance issues with the bike whatsoever... she runs fine. A little "pop" every now and again on trailing throttle after WOT to high R's but that is A-OK - doesn't happen as often as it used to now that I had it tuned. Thoughts?
 

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I assume what you're seeing is burned oil (white/blue) and not a rich fuel mixture (black/brown) or carbon (usually black but can be brown)...if it's on initial startup the worst scenario can be some oil leaking past the valve guides while sitting overnight...pull the left plugs and look for oil (wet black) or carbon (dry brown/black) fouling, and check the muffler outlets for the same...my plugs are white on the very tip, and brown the rest of the way down, and running a finger around the muffler outlet when cool yields absolutely nothing...look into the plug holes with a light with the piston at TDC...is it covered with crud or mostly clean metal with slight tan carbon streaks (normal).

Gassing her just after startup when she's still running rich can cause unburned fuel to get by the cats before they start cooking, and it's normal.

The big question and concern is does it do it after it's warmed up, particularly after a closed throttle deceleration followed by rapid throttle application...if it puffs white/blue after doing what I described, then that can mean oil is being pulled past the valve guides or most likely the piston rings by high cylinder vacuum...wear, improper break-in or thin oil can be the cause...turn one mirror down to observe.

Most likely what you're seeing is some normal oil vapor escaping the oil tank and engine when you shut down, travelling up the breather tubes into the airbox, and getting burned when the engine is restarted...unless your plugs, piston, or exhaust outlet looked fouled...water vapor from a cold running engine can also look like burned oil (white).

Gary in Fairbanks
 

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Here's a reply to Ninja-Matic that others may wish to add to or comment on:

"Hi Ninja-Matic, despite your concerns, these bikes are fun to experiment with, and it's good to see you're doing just that...but just consider this, you're now the builder.

From your description, your plugs and pistons appear normal.

The bike will run with a rich mixture for a minute or two until the idle slows down to normal, so some black smoke with throttle application then is normal given the setting of your pot#1 (6).

The factory pipe and fueling setup was normal, and showed as such, then you added the fuel controller, and changed the air filter and pipes w/o cats...new rules now apply.

Cobra is EPA crazy in recommending a 1 setting on pot #1 with an O2 model controller, and setting correctly per F/A probes on the dyno as you did will control after run closed throttle popping on deceleration...popping through the intake is a sign of a lean fuel air ratio that ignites the next incoming batch, because the slow burning lean mixture is still flaming away in the combustion chamber when the intake valve opens for the next batch.

Black smoke at idle just after start is due to your 14:1 F/A ratio plus the bike's adding of extra fuel like a choke to get things going on a cold engine...the O2 sensor operates only in a narrow range (maybe 13-15:1) and is probably not warmed up enough by it's electric heater to function properly right away at startup = some initial black smoke.

One thing about the Cobra unit is that the #1 pot affects F/A ratios well into the engine's rpm range...to get a nice idle mixture means that you may be running a bit rich in the middle range at steady part throttle and certain rpms ...opening the throttle brings pot #2 into play (based upon the change in position of the TPSensor/rate of voltage output increase), and at WFO she goes to pot #3.

That's the reason some go to the Vance& Hines (better) or Powercommander (best so far)...they offer many more "load boxes" in their F/A map to add or remove fuel...load boxes are determined by % throttle opening versus rpms in a matrix box stored in the PCIII and adjustable by you with a laptop connected to the PCIII's serial port...you have only three adjustments that cross many load boxes with the Cobra unit (the rest are fixed), while the PCIII has one user adjustable every 250 rpm and about every 10% (I think) of throttle opening.

I recommend you get a PCIII if you really want to be happy in the long run.

One last thing...clean your plugs, and run at whatever constant speed and throttle setting you usually do for several miles...being careful of other traffic kill the engine with the red switch, pull the clutch, stop, and pull a plug or two and read the color...that's the only way to really tell if the controller is giving you the right mixture at the most used op mode...tan is good, all white or black not.

Gary in Fairbanks (I'll post this as a reply as well if it's ok?)"

Edit: Spelling
 

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Discussion Starter · #5 ·
Gary - Tan is more like the color of the plugs - although - with the lighting in my garage at night (lol) I'll call it "gray".

Everything appears normal otherwise. Perhaps i'll start using some Seafoam every 500 miles in a fresh tank to keep things clean.

Most of the fuel stations around my house have the single hose with your choice - no telling who put 87 octane in their car before I got to the pump and how much of it is still left in the hose.
 

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The additive would be a good thing, especially if the quality of your fuel is poor, or has ben compromised by trucks that also haul heaver fuel...the thing about 90 or better octane is that is is best for our high compression engines, and those that ran with a single plug due to the coil wire issue may have developed some combustion chamber deposits from incomplete combustion, this is because the 90 octane is relatively slow burning without the second plug to ignite the mixture sooner and make more cylinder pressure before the exhaust valve opens...that's why fuel mileage and power is down and emissions likely up on affected bikes ...stuff like Seafoam or spray-in 2-cycle engine tuner from OMC will help decrease it in my experience.

I've de-carboned all my 2 and 4-cycle engines without cat convertors annually with the Marine tuner due our poor quality of fuel, and use stuff like Seafoam on the rest to keep the fuel injection and combustion chambers clean...due to a recent change in formulation of the slow-acting engine tuner, I'm changing over to Seafoam this year.

Back in the 60's we used to pour a can of carbon cleaner into the carbs until the engine stalled, let it sit overnight, and with a big white cloud of smoke and carbon run it out the next morning on the way to work...can't do that now and Methyl Cellulose (the cleaning agent/think the name is close) is effective but bad stuff to breathe.

Gary in Fairbanks
 

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Well Gary, let me be the second after Ninja to Thank You. Very interesting reading, I was going to go with the Cobra swepts or the Morton's (the blueing issue has me leaning toward the Cobra's), if Vance and Hines didn't produce the 2 into 2 Big Radius. I also was leaning toward the PCIII, even though cobra recommends their fuel pak. Just wanted to thank you for a interesting and informative read. I've always checked the plugs like that to see how its running, but never went into the why's and why not's. Thanks again.
 

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One thing that puzzles me, and I have no way of knowing short of calling Cobra, is why they offer both an O2-sensor equipped and regular fuel controller...perhaps it's to compete with the PCIIIex that Dynojet offers, and the Vance & Hines unit with an O2 input.

CARB regulations may require it for use in California, but having an O2 sensor fighting, albeit over a narrow F/A ratio range, a richer setting the tuner or owner desires would seem counterproductive...and the ECU has to be electronically fooled into thinking there's an O2 sensor still attached so it doesn't throw an error code on the non-O2 model.

Of course, short of the improved sound we all enjoy, adding an after market exhaust and intake really does little to improve an already excellent running bike, and may violate all manner of State and Federal emission and noise abatement laws (Bad Boyz).

One experiment I'd like to try is to remove the control cables and lock the EXUP valve in a fixed open position on the stock bike and run it on a dyno...Yamaha claims it adds torque, and it might, but if you listen closely, or remove the EXUP cover and drive, you'll see the valve open and exhaust sound improve during acceleration...I believe it's also there to tone down exhaust volume and help meet sound certification requirements...any, and how much, torque improvement would be interesting to really document.

Gary in Fairbanks
 
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