Running rough below 4K

[mznyc]

Hi Guys,

Did a first home tune-up,tourqed heads,adjusted valves to euro spec,changed ,gapped spark plugs,balanced Tb's,adjusted TPS.Bike running pretty well but below 4k she will back-fire(more of a burble) and be a little rough on off-throttle.Checked TB's balance and TPS today and were spot-on.Where should I concentrate on as a possible fix.I know a PC 3 may help but feel I should get it closer without.

Thanks,

Michael

02 Scura with MG Ti + ECU

[Greg Field]

SMall exhaust leak?

[mznyc]

Hi Greg,

Checked all exhaust and TB boots and everything was snug.

Figured I would try TPS and TB balance and I cant seem to get correct readings for TPS.On my DMM,I have it set to mV setting but get 3 digits a decimal point and another digit.When I move the TPS with the TB's disconnected,right hand idle screw backed out,Fast idle cable disconnected,key on,not running,the numbers change but dont get in the 150 range.they go from . something to 50. something mVs.I would think I would see 150.0 mV.Am I mis-reading,mis-setting the DMM?

Thanks,

Do you still have Mistral X overs?

[GuzziMoto]

And I would double check your valve clearences. Doesn't take long and can screw with the way it runs if they're too tight or too loose. When you make a change and the bike doesn't run right after, I go back over the changes I made. If it ran well before, there's no reason it should need a pc to run well now.

[luhbo]

...

The Ti Race ECU usually comes set at "0" for the idle trim. I'd recommend increasing in increments of 3 until it runs okay. Going as high as 15 will be too rich at an elevation of ~4,000' MSL and rideability problems will ensue.

...

 

Now that's one interesting post. Are you sure about that? If so, then it's a good point for TuneBoy owners. How do we adjust the idle trim??

 

Hubert

[docc]

Hi Greg,

Checked all exhaust and TB boots and everything was snug.

Figured I would try TPS and TB balance and I cant seem to get correct readings for TPS.On my DMM,I have it set to mV setting but get 3 digits a decimal point and another digit.When I move the TPS with the TB's disconnected,right hand idle screw backed out,Fast idle cable disconnected,key on,not running,the numbers change but dont get in the 150 range.they go from . something to 50. something mVs.I would think I would see 150.0 mV.Am I mis-reading,mis-setting the DMM?

Thanks,

Do you still have Mistral X overs?

GuzziMoto makes a good point about the valve adjustment. This is step one in the tune-up. 0.006/0.008 is good medicine; especially in the hot weather.

 

With your DMM set to the 2 vDC range, you are looking for a closed throttle reading of 0.150 +/- 15.

 

After 10 tune-ups, I've found my Sport runs better at 0.165 (165 mV);especially in the hot weather.

[dlaing]

Hi Greg,

Checked all exhaust and TB boots and everything was snug.

Figured I would try TPS and TB balance and I cant seem to get correct readings for TPS.On my DMM,I have it set to mV setting but get 3 digits a decimal point and another digit.When I move the TPS with the TB's disconnected,right hand idle screw backed out,Fast idle cable disconnected,key on,not running,the numbers change but dont get in the 150 range.they go from . something to 50. something mVs.I would think I would see 150.0 mV.Am I mis-reading,mis-setting the DMM?

Thanks,

Do you still have Mistral X overs?

I know you did not ask me, but when have I been one to be muted.

Something is wrong.

Bad meter? bad reading? bad TPS?

Test the TPS by reading it while turning the throttle. It should go smoothly from about 525mv at idle to just under 5000mv at WOT (wide open throttle) Mine is about 4850 at WOT, but exact number for WOT is not critical.

which wires are you probing?

 

 

Now that's one interesting post. Are you sure about that? If so, then it's a good point for TuneBoy owners. How do we adjust the idle trim??

 

Hubert

I don't think Wayne ever finished the TuneBoy diagnostic software that would control the idle trim.

We should pester him about it.

Otherwise we need AxeOne, TR's VDSTS, or TR's MBDSTS. (hope I spelled those right)

[luhbo]

If you don't get reasonable readings, then you have probably mesured between the wrong points. Put minus to a solid ground on the bike or battery minus, then check the outer cables (1 or 3). One should give a constant (+-) 5V reading, the other cable is the signal, going from about zero (or 400 or 500 mV) up to nearly 5 at WOT. This must work, or the bike wouldn't run at all.

 

Kevin, if you're sure and it seems that you do so, then the TuneBoy software in its actual state is probably not state of the art

 

One other very good moment to mention of how happy I am with the My15M

 

Hubert

[BrianG]

Minne was starting to run poorly below 3000 RPM along with the occasional tip-in or light throttle back-fire. Notably worse when hot. I didn't tune it this last winter, I guess because I got distracted with the clutch replacement and the transmission reseal projects.

 

Anyway, the long and the short of this story is.......

 

I pulled the valve covers today and gaged the valve clearances... both exhausts were very tight 0.002" and the intakes were 0.003 (lt) and 0.004 (rt).

 

I wonder why it ran the craps at low RPM???

[mznyc]

I did the valve adjust a couple of hundred miles ago and checked them a couple of times and they were spot on for euro spec,I'm not home but I believe that was .15,.20.Which I read here that would give me more mid-range,which i always felt was lacking with the bike.I'll try to take a look at them again this week.

What valve setting are you guys using for a Ti/ECU set-up(stock other than that) that works

 

I was able to get a good reading on the TPS in the key on/not running setting of 150mv,but when I tried to get an idle setting was running into the same problem as before,geting readings off the chart.Must not be making good contact with the probe.Using paper clips on the two outside wires.

 

Also,do most of you,disconnect TBs,back out RH idle screw,key on/not running method to get the 150mv reading?If so i would assume we would have to re-balance Tbs everytime we did this as we're changing a good idle setting.I did re-balance after doing this and bike is running better with less back firing and a little smoother below 4k,I'll continue to tinker but may have a Mistral X-over,and Todd PC3 in my future.

 

 

I did the valve adjust a couple of hundred miles ago and checked them a couple of times and they were spot on for euro spec,I'm not home but I believe that was .15,.20.Which I read here that would give me more mid-range,which i always felt was lacking with the bike.I'll try to take a look at them again this week.

What valve setting are you guys using for a Ti/ECU set-up(stock other than that) that works

 

I was able to get a good reading on the TPS in the key on/not running setting of 150mv,but when I tried to get an idle setting was running into the same problem as before,geting readings off the chart.Must not be making good contact with the probe.Using paper clips on the two outside wires.

 

Also,do most of you,disconnect TBs,back out RH idle screw,key on/not running method to get the 150mv reading?If so i would assume we would have to re-balance Tbs everytime we did this as we're changing a good idle setting.I did re-balance after doing this and bike is running better with less back firing and a little smoother below 4k,I'll continue to tinker but may have a Mistral X-over,and Todd PC3 in my future.

[Mr. Bean]

My Ballabio is stock and the only way I ever found to get it to run right was a method told to me by Micha at Moto International. It is somewhat basakwards from the manual and the normal procedures I've found on this and other sites but it sure does work.

 

Step 1) Set valves to world specs.

2) Open bleed screws 1 turn out

3) Synch TB's at just off idle. Approx 1800 to 2000 rpm

4) Set idle to 1100 +/- 50 rpm using the set screws

5) NOW, and only now, set the TPS to 3.6 degrees (485 mv)

6) Set fuel trim to 0

 

My bike has never run better. I have a PCIII but I have a zero map loaded on it right now. I'm still going to get a dyno map built someday just to see, but I tell you those guys at MI know their stuff.

 

 

Randy

[mznyc]

Randy,After you sync the TB's,you back off both set screws,say a 1/4 turn,one at a time to get correct idle,and not worry about balance?I would think not matter how careful you were they wouldn't be balanced dead on.

How do you set fuel trim?

Thanks,

Michael

[Mr. Bean]

Michael,

 

The balance of the TB's is directly related to the synch rod between the TB's. You'll notice that the throttle only directly controls the left TB. The right TB is driven by the synch rod so all the synchronization between the TB's is controlled only by this. Once you set the bypass screws to 1 turn out (the ones beneath the TB that use a flat blade screwdriver) leave them alone.

 

Then I back the right set screw off a bit since it really does nothing on my bike once the synch rod is set right. I move the left set screw to get an idle around 1000 or so enough to keep the engine running is all...doesn't matter since it is not related at all to TB balance. Then using the throttle, I rev the engine up and hold it around 1800 to 2000 and see where my balance is on my TwinMax. I adjust the white knob until the TB's are balanced. I don't do it any higher than that. Micha told me that at higher revs you are not accomplishing anything by trying to get a balance with the TB's adjustment rod.

 

At this point I simply use the left set screw to bump my idle to where I want it. 1100 +/- 50 RPM. The right set screw is not touching the throttle plate at all. If you want, you can use the right screw to try and get perfect at-idle balance since the moment you touch the throttle it is lifting off of both set screws anyway. Just don't touch the left one anymore OR the white knob! Then when I have the idle speed right, I loosen the TPS and set it to 3.6 degrees...or roughly 485mv.

 

The idle mixture is adjusted via the computer. I use the VDST software from TechnoResearch to do that.

 

 

Hope this helps.

 

Randy

[luhbo]

....

At this point I simply use the left set screw to bump my idle to where I want it. 1100 +/- 50 RPM. The right set screw is not touching the throttle plate at all. If you want, you can use the right screw to try and get perfect at-idle balance ....

 

At this point the procedure is worth to be discussed. As you cannot be sure whether 1 turn open for the left screw means the same as one turn open on the right one (tolerances, wear, debris ...) you would better balance the flaps with both screws closed. Closed is closed.

After having reached a good balance at 2000 or more, turning the white knob, you can open both screws the same amount (you prefer 1 turn) and adjust the left set screw to get an acceptable idle.

 

At this point you will probably notice a remarkable misbalance between left and right body, if you have your TwinMax still attached. This misbalance should not be adjusted with the right set screw, use the bypass screws to achieve a good balance. That's what they're meant for.

 

At such small opening angles the influence of tolerances of the duct or flap diameter, sharp or damaged flap edges etc. is remarkable. It's the bypass screws that help to compensate these effects.

 

Hubert

[Mr. Bean]

Hubert,

 

By opening the bypass screws BEFORE balancing the TB's you are taking any mismatch into account. If you open them up afterward now your balance can be off as you mentioned. As I have understood, and found in my own tuning, using the bypass screws AND the TB synch knob to get a balance can result in chasing one's tail to get it balanced across various RPM's. If one uses the bypass screws only for the purpose of allowing a fixed amount of air past at idle to match a given mixture setting on the CPU to get a given A/F ratio...then one can eliminate them from the TB balance equation. By only using the TB balance knob to control balance it makes it easier to separate each issue. Again, I admit it is different from some procedures but it sure worked on my bike. YMMV

 

Randy