Vibration and running lean

[Sparti]

I've recently uploaded TB Tune 20273, which is for NON SAI and aftermarket exhaust. Prior to this i had TB Tune 20214, which is for the arrow low mount.

My bike has a BMC filter & Zard.

The 20214 is a pretty good tune and the bike starts quickly with this tune. This tune does run a bit rich but with my BMC it cuts that back a bit. BTW I gauge the richness of the bike based on the carbon buildup on the exhaust pipe.

I loaded the 20273 on recommendation from Bad Santa. I believe this tune is for twin high mount exhausts and am not sure running this tune with a 3 -1 low mount causes the bike to run leaner. Anyway, first things i noticed was the the bike takes quite few more cranks to start and the note of the exhaust sounded deeper. To check out the richness/leanness of the tune, i gave the end of the can a good clean and then went for a ride.

The tune does seem to give a bit more grunt but, and this is the reason for the title, I’m getting vibration through the handlebars and pegs that i didn’t get using the 20214 tune. I know the bike is running leaner as the end of my can is as clean as anything with no carbon build to speak of.

FYI, i recently made a change to my velocity stacks that caused my bike to run leaner and this also caused the bike to vibrate at constant revs. I ended up stopping halfway on a 200k ride, pulling the items off my bike to see if they were the actual cause of the vibration. And they were. With this and the lean running 20273 tune I came to the conclusion that lean running engine = vibration.

Am I right, does running an engine lean cause engine vibrations or is it something else?

[Bad Santa 1050]

Couple thoughts/questions...

- Any noticeable difference fuel economy/mileage?

- Did you try the altered Velocity Stack setup with the 20214 map/tune as well? If so was there any vibration for the same circumstances?

- Where in the rev range, gear (approx speed) and how much engine load was there when your vibration occurred?

- Might be an idea to compare the Ignition advance values at the rev/TP range where the vibration is happening in both 20273 and 20214. Let know if there is a noticeable difference in the advance values.

- Perhaps add 2-5% in the fuel trim in the rev range/load or throttle position where the vibration occurs? Then retry and see if it eliminates/reduces the vibration. Repeat as required?

My thought (unproven theory) is that motor is happiest (makes best power) at a given air fuel ratio and ignition advance setting. Leaner than ideal will be less produce less power, as will excessively rich. Depending which of those tunes is closer to ideal (for your particular setup) that one will give you better power whether it is more rich or lean.

The vibration - sounds a touch concerning. Is it just vibration? or is it pinging as well? When it occurs, is the motor labouring at all? I've had pinging before whilst experimenting, but did not get vibration at the same time. You have my curiosity perplexed... (use of the word "aroused" is probably not a good idea around here... bit too much man-love for comfort...)

[Brrapp]

Wouldnt have thought so without pinging, lack of power and run hot yes, unless the timing is too far retarded (to reduce ping) but that would just create more heat, so no.

Dunno, unless one cylinder had an air leak, but then there'd be pinging.

I could talk you in circles for hours, better ask someone else.

[Sparti]

I should clarify what i did to the velocity stacks. This was about a month ago ( whilst running 20214 tune), I installed some Vortec Cyclones, check the site out if you dont know what they are Vortec Cyclone - Save Gas, Boost Horsepower

They are suppose to mix the air and fuel more evenly to produce a better, cleaner burn.

Anyway I had bought these things a few years ago, put them in and ran them for a while. Everything was fine but I ended up pulling them out a while back when I had idling issues (not related) and never put them back in. Since then I've changed my exhaust to a Zard and my tune to 20214.

So as I was saying I ended up putting them back in a month ago and went for a long ride. Within 1 hour my hands and feet were numb from vibration in the bars and pegs. and power was down in the upper rev range. As the only thing I had changed on the bike were these cyclon items i decided to rip the air box open while we stopped for lunch and pull them out. Well it was them that caused the vibration as the rest of the day was silky smooth. I couldn't work out why they caused the bike to vibrate and all I could come up with was it was running lean or played around with the A/F of the tune or something like that.

Now after uploading the 20273 tune as mentioned I'm getting similar vibration - now my bike has never vibrated so you notice when it does. It's not a rough vibration , more I high frequency vibration and only at 4k and above.

Im getting a custom tune done in a few weeks time so this will be a moot subject by then (I hope). Im just curious as to what can cause the vibration.

[antisocial]

Custom tune sounds like a good idea.

[Joe Houle]

All the cyclone units will do is restrict airflow. Speedy does not make max power at the "ideal" A/F ratio. I have seen this with my own eyes during tuning. Some places it wants to be rich, some places it does not. If you tune to A/F you will get a twitchy, lumpy, bitchy bike.


You know what I suggest. DEF use it as your starting point on your custom tune, I think it will save you time($$$) on the dyno..

[Joe Houle]

Also, just for my own curiosity, can you put the cyclones back in #1 and #3 and test ride to see if the buzz is still there? I know #2 likes to breathe a little more

[Bad Santa 1050]

I agree with Joe regarding the A/F ratio - for the purposes of brevity I simplified my theory/understanding down to of the two factory maps being referred to, one is closer to the ideal conditions for speedy to make best power. Those conditions being, the combinations of a/f ratio, amount of fuel, amount of ignition advance etc, not just the a/f ratio.
I've seen first hand, where the motor was tuned to a flat a/f ratio of 13.2:1 because that is what a certain tuning company/religion claim is best for power... It was better than standard, but there was still room for improvement. The fact that richening the target a/f ratio alone improved feel and performance, proved that "13.2:1" is not the ultimate a/f ratio for best performance after all. Let alone the fact that adjustments to the other variables will result in further improvements, which will again require further fine tuning with the fueling.

[Bad Santa 1050]

With the vortex generators you got - I am intrigued. When you get your custom map done next month, perhaps get it mapped with them fitted aswell, to see if there really is a gain. I won't argue that they don't restrict the intake, however reducing/restricting the intake MAY increase the velocity of air going into the motor.
Basic example: run a garden hose with no nozzle fitted, with tap fully on, water flows out, but without that much pressure. Then cover most of the end of the hose with your thumb, and the water coming out of the hose thru the small gap created by your thumb produces a stream of water with sufficient pressure and velocity actually hose leaves or sand off a patio, where as without your thumb there, you would just wet/flood the same patio, with leaves moving due to them floating away rather than blasted by the jet of water.

My guess is, if the there is almost no load on the motor when these vibrations occur, and they are caused by insufficient fuel to match the increased flow of air into the motor, the combustion process is probably less than ideal, and perhaps the reduced ignition advance is preventing pinging. I suspect BRRAPPP is possibly in the correct ballpark...

[Joe Houle]

they are not increasing the velocity. they are just an obstruction that is disturbing the flow. That is why he feels it falling off on the top end. Not sure of the dynamics involved that are producing his buzz, but these things are bad. Just get real velocity stacks and toss these in the trash..



*forgot to mention, Speedy is very sensitive to running lean, and it clearly shows in the operating temps. The TOD is fairly rich, and most people have commented that they see a 1-2 bar drop in temp..so if she is up a bar, there ya go