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Discussion Starter #1
We're tuning my 900SS using the DesmoTimes manual and a few threads from here as guides.

First thing was to test the TPS.

My computer version is 1.5.

I'm supposed to get a reading of 150 mv at the sensor with the bike not running but with ignition on. When we first tested it, it read something like 430. So I adjusted the TPS and got it to read 155, that's as close as I could get it.

So then we went over to the throttle stop screw (allen head) and adjusted it to where getting a reading 420 - 460 mv. We achieved a reading of right around 440 mv.

Then we checked my TBs, all is good. The front cylinder is less than a half a cm off when using the sync tool. It's supposed to be within 2 cm. Good there.

We bottomed out the air bypass screws on both TBs per the DesmoTimes manual instructions.

Only one problem, in doing so we messed up the mixture, and in order to set it right, we have to have the CDSTS or Mathus tester along with an EGA.

So we borrowed an EGA.

I was thinking along the lines that if we could stick the EGA tube in the exhaust pipe (remove the bungs that are in place from the factory on each header pipe) and try and get a reading there, adjusting the air bypass screws to try and reach a level that is even on both pipes, that it might be better than nothing.


We need to get the bike up to temperature, so we started it.

At idle, the front cylinder is popping like crazy (how it would normally pop with these bikes from 3500-4500 rpm).

We had to adjust the throttle stop screw out so far to acchieve the reading we needed that now the idle adjustment screw doesn't reach to do it's job. Essentially, the TSS is doing the job of the idle adjustment screw.

And, we can't get the vertical cylinder exhaust pipe bung out at all. I got it to back out a bit, but then it stuck, couldn't go backwards or forwards with it. Won't budge. Sprayed some PB Blaster to try and penetrate and see if it would work, nothing.

*sigh*

So now....anyone have any ideas?
 

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Chilehead
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When you set the TPS did you first back off on everything and make sure the butterflies were fully closed? You have to totally back off the stops to do this, if not everything else you've done is meaningless!

This was just on the other list:

For all the Ducati injected models you should start the balancing process with the air bleed screws fully closed. The air bleeds are only for use in balancing out the vacuum readings at tickover speed and may not need to be open at all. The initial TPS voltage reading is set with the butterflies snapped fully shut. (i.e. the throttle closed and the throttle stop screw backed right off.) This is the important reading as it sets a datum for the fuel maps that the CPU to works from. Make all the adjustments and set the tickover to the rquired rpm with the stop screw when you have finished. The voltage at tickover speed is not a fixed figure so don't try to set it to a voltage. The FIM site has a good write up of the correct sequence: http://www.fuelinmoto.com.au/fimfaq.html#q17
Read the Q.7 and then all of Q.11 for the sequence. It sounds a bit long winded but it does work.
Tom
 

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Discussion Starter #3
st2lemans said:
When you set the TPS did you first back off on everything and make sure the butterflies were fully closed? You have to totally back off the stops to do this, if not everything else you've done is meaningless!
Yes, we did.
 

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I can't recall specifics right now but I think you initially set th TB balance with the air bleeds fully closed and then fine tune CO with airbleeds. Did you do that.

Seems that the poping cylinder is extremely lean. Best to start over.

I recall the F.I.M and the sigma performance web sites give a very good write up on the TPS and TB balance procedure.

kind regards,
 

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Discussion Starter #5
yes, you start with the air bleed screws completely closed.

JDuc said:
We bottomed out the air bypass screws on both TBs per the DesmoTimes manual instructions.
 

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"We had to adjust the throttle stop screw out so far to acchieve the reading we needed that now the idle adjustment screw doesn't reach to do it's job. Essentially, the TSS is doing the job of the idle adjustment screw."

Not sure that i follow this part. The only screws I can think of are - The idle or throttle stop (one on each TB) - the air bleed -(one on each TB) the throttle linkage adjuster (for synching the TB only one of these) and on the right hand TB the adjuster for the fast idle control. What was it that you adjusted that is holding the throttle such that the idle adjuster doesn't reach?
 

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Discussion Starter #7
as it's referred to in the DesmoTimes manual it's called the throttle stop screw (as you called it The idle or throttle stop (one on each TB))
 

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Ok - I doubt I'm going to be much use - but the 430 initial reading seems very wrong, as I understood (and I await correction) the TPS, even out of adjustment is not likely to be as high as 430Ma, with that reading I would suspect that one of the throttle stops was still egaged.
Best advice was given above : redo everything - doesn't take long.
 

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Discussion Starter #9
we're planning on redoing it all tonight.

Pulling everything back appart.

I'm beginning to think that the front cylinder popping has more to do with a valve being out of adjustment. There's no way the popping (backfiring) that we're hearing could happen unless the intake valve were still open when compustion were taking place...
 

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Make sure that the butterflies on both TBs are fully shut. In other words, there is no throttle-stop-screw(s) or cable/linkage limiting the motion. The plates are as fully closed as they can go, mechanically. Don't forget, that this is an abnormal condition (meaning the bike never runs down here), but this is where the 150mV setting is meant to be referrenced at this point.

(NOTE: I've never done this adjustment yet, so somebody chime in here to say that this is indeed right or wrong. But I've read thru the steps, and this is what I believe is true.)

From your write-up, it sounds like you "found the setting at 430mV", and that sounds like a setting more typical of the TB's when they're held open by the idle set screw.
 

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Discussion Starter #11
Stick said:
Make sure that the butterflies on both TBs are fully shut. In other words, there is no throttle-stop-screw(s) or cable/linkage limiting the motion. The plates are as fully closed as they can go, mechanically. Don't forget, that this is an abnormal condition (meaning the bike never runs down here), but this is where the 150mV setting is meant to be referrenced at this point.
correct. We backed out the throttle stop screw all the way, to where it didn't touch when we closed the TBs

From your write-up, it sounds like you "found the setting at 430mV", and that sounds like a setting more typical of the TB's when they're held open by the idle set screw.
no, the initial setting, before chaning anything, was at 430, we adjusted it back down to 150 on the sensor, then went over to the set screw and adjusted it to 440 there.
 

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You are going to have to go all the way back and start over.
Something is wrong with the way you took your initial reading.
If the TPS was at 430mv completely closed [which I honestly would find amazing] The bike would have really run like crap, if at all.

14-15 mv's off either way I can believe...but 280 is ridiculous.

I think you have to go through the whole process again. back off the screws [main and balance] and visually check that the butterflies snap fully closed, then check your voltage reading

then after adjusting, snap them open once or twice to see the voltage spike and return to 150 [+- 2mv's]

sorry, but it's the only way.
 

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Discussion Starter #13
I know - I'm planning on it...but I can't stop and do it now...;)

I've already been told to do it again, and already planned on doing it again

:D
 

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1. Disconnect the throttle cable from the TB.
2. Disconnect the "other" TB from the one with the TPS on it (Horizontal TB has the TPS, on the SBK) - by pulling the clip on the back of the linkage rod behind the white plastic sync adjuster thumb-screw.
3. Screw the idle/master stop screw all the way out to allow the TB valve to fully shut in the TB. Snap the throttle open and closed and check the plate is fully closing inside the TB.
4. NOW, measure and adjust your TPS to 150mV.
5. Reattach the link rod, the throttle cable and screw the idle/master stop screw in until the TPS reads the appropriate idle mV
6. Screw in the TB bleed screws, and hook up the vacuum gauges
7. Sync the TBs to each other, and fine-tune with the bleed bypass, as necessary.
8. Check your CO/mixtures and adjust your ECU trim as appropriate.
 

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Discussion Starter #15
yes OldBaldy - I'm fully aware, thanks for reinterating what has already been stated a few times and I already knew....

lol

;)
 

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Jeez....having a bad day? Sorry I wasted YOUR time....
 

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Discussion Starter #17
sorry, it just gets old when you have 10 people just repeat each other...;)
 

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No problem....I'll try to avoid your posts for help in future. I'm sure you'll get all the help you'll need from those other 9 that you say repeated themselves :)
 

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Discussion Starter #19
welp, I'm glad you took it so personal!

have a nice day!
 
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