Fast Idle set to 25% or won't idle

[torpedo51]

Hi,

Not too long ago, I acquired a 1991 907ie. The bike starts and runs great with one exception: the fast idle lever is required to be set at 25% when the bike is fully warm, or the bike won't hold idle. The 25% setting keeps the rpm at 1000.

The previous owner decided that the problem didn't merit repair. I felt the same, except now that I'm trying to sell the bike, the potential buyers don't agree. The bike consistently gets 42mpg. I live in Southern California where the climate is consistently nice.

I read all the articles about cables getting pinched and procedures to clean the electrical contacts and adjust the components of the IE system. I was wondering if there is something even easier that could be the problem. The bike runs too good, other than this mild annoyance, to merit a trip to the $$$ shop. The only other symptom is that it seems a bit underpowered climbing from 1000 rpm to 2000 when accelerating from a full stop (my old 750 Paso seemed just a bit more peppy).

??

[blazing928]

sounds like the throttle butterflys aren't set correctly. I think you do this with a multimeter.
The bike should idle with the cable disconnected.
Sell it cheaper and get the new buyer to sort it out by getting it correctly set up at a knowlegeable repairer.
There are quite a few adjustments to be done to bring it to a basic setting. That needs to be done before one plays!
Tell the buyer to get a FBF stage one chip, the bike and rider will both enjoy.

[higgy]

details on setting it up can be found here

http://www.bikeboy.org/ducati2vthrottleb.html

[Laddie]

potential buyers are always right...if they don't agree they won't pay.

at 42 MPG and the lack of "go" at low revs it's not running "right"; most likely lean AND the TPS not adjusted correctly.
the bikeboy tuning guide is the way to go to do it correctly; assuming no other mechanical/electrical faults it will run like a charm. By the sound of things you haven't ever had it tuned and the last guy didn't get it done right either - so adding gas with the fast idle is just helping to compensate to make it turn over.

option 1
a "quick fix" would be to jam some Blu-tac in the "choke" (fast idle lever) to prevent it returning closed.
caveat emptor; vendor emptor.
It would be wise to buy a security system and guard dogs so the new owner doesn't club you to death in your sleep.
You can afford these with all the dollars you save by not doing it properly.

option 2
lift the tank and screw up the idle manually.
it's a pretty easy task - despite the 1/2 hour disassembly; the screw and lock nuts are almost impossible to get at unless you remove the lot.
all the fast idle does is open the butterflys and move the TPS.

reality: all this is doing is masking a sick or poorly tuned bike.

Think twice about selling it with a patch-up repair; be fair...we here at the Paso forum will likely get to meet the new owner at some time...and he might be cranky if he finds the Blu-tak.

[torpedo51]

Wonderful tech article. Im reasonably adept at mechanical procedures, but the complexity here seems intimidating: particularly the bits about sampling voltage to throttle position, mercury tube synching and CO2 sniffers. I'd love to hand this procedure off to one of the three shops here in L.A., but they've proven to lack integrity.

Anyone have a shop recommendation in L.A. for me, or perhaps someone willing to train me?

[higgy]

Tried Bevel Heaven ?

Bevel Heaven ~ PO Box 340, Concord, California 94522-0340 USA ~ Tele: 01-925-798-BEVL (2385)
Open [generally]: M-F 10 - 5 [pst] ~ Closed: Sat/Sun ~ eMail: Shop<at>BevelHeaven<dawt>com

There is a listing in the 750 FAQ on making your own manometer. you can even make your own taps out of a small piece of 3/16 brake line and a 5x0.8 die. I recently had to get a set of rotors for my wifes xterra, the guys at Advance Auto gave me a piece for nuttin honey Course I did spend some bucks on rotors and pads

[Laddie]

despite the fact the bike seems to run well at least check compression first; if the compression is OK that is probably the best selling point to a prospective buyer in the market for a 907; it will also prevent wasting time tuning if the bike is failing a compression test.

if it really does run well except at idle than there isn't much point balancing the throttle bodies (unless you want to); just check the TPS setting when the throttle is closed and the fast idle is off.
This is relatively simple to connect a multimeter direct to the TPS or at the pins on the ECU.

The TPS can be faulty; I have replaced one that would not "zero"; it wouldn't go below 150 mV...but the bike still ran OK and idled like a charm. The TPS test is quite simple and then you can work out if the throttle bodies are closed fully and re-set at idle at the same time.

[torpedo51]

Approximately what MPG would indicate a healthy bike? 45? 50? Don't bother giving me the disclaimer about how I drive - I drive like a grandma.

I think you're suggesting that I can check the TPS without fussing with any of the other adjustments? If so, I'll start with that.

I won't be using any blu-tak, non-stock chips, building any manometers, taking any shortcuts, or selling a bike dishonestly. I'm a purist.

Assuming the "throttle adjustment" is a standard procedure at any Ducati shop, do any of you have a ballpark price range? The shops here quote me at 3 hours for a total of $330. I would simply have it done, if it weren't for the lack of integrity abound. That shop in Concord is about a 380 miles away from here.

[Laddie]

a healthy "standard" bike would be around 38 - 40 MPG with normal cruise; fanging it might drop it to low 30's.
if it has a FBF or after-market chip it could be as much as 10% lower (add fuel = more horsepower theory)

yes, you can check the TPS without all the other stuff.
I still strongly recommend the compression check first (which can be done very easily, too).
You can partially test the TPS performance at the ECU (see below) without taking all the fairing and tank off
You can connect the meter and test what you get with the fast idle lever at 0, 25%, 50% and 100%.
I'll go out on a limb and guess that at 25% you have 140mV and at 0% you have < 100mV.

This is an extract from a service bulletin issued by the factory in Oct 1992.
You can either follow the procedure or start at the end (where your TPS should be set)

Model 907 & Cagiva Elefant 900 IE & GT models

remove the filterbox cover and the air filter; unscrew the anti-sticking screws i) and starter adjust ii). Screw up to the moment that the throttle is totally closed. Check this position by touching the filter side and having the throttle operated many times. (open the throttle a little and snap it closed ounce or twice)

Connect a digital voltmeter (accuracy=1mV) to the pin no 11 (-) and no 17 (+) of the central box terminal board iii) Then check that the voltage reading (switchboard On) to be 150 mV ± 15mV. Otherwise loosen the potentiometer iv) fastening screws setting their angular position up the the mentioned voltage figures are got. During this operation horizontal cylinder throttle must be forced to stay closed. (be careful what they say about being forced, what they actually mean is do not allow the turning of the potentiometer to open the throttle body butterflies)

Using the anti-sticking screw i) of the vertical cylinder (master) adjust the throttle opening up to a voltage reading of 300mV ± 15mV. In the same way adjust the anti-sticking screw of the horizontal cylinder up to the contact with its support, or when the voltage figure previously stated starts to increase. At this point the air flow rate of the throttle at idle rpm ratio is in condition to allow a positive and negative adjustment (rpm increase or decrease) using the by-pass screws.

Adjust the by-pass screws at one opening turn and after the usual preparation, arrange engine starting; under these conditions (20°C approximately for air, & oil temp.) rpm range must be stabilised at 900-1300 rpm approx. On the contrary, ( if this is inconsistent) check again with anti locking screws loosened, that throttles are resting on the duct indeed. (throttle body butterflies properly closed)
Go on with the usual procedure of adjustment (see our service bulletin No. 149 dated 20/06/90) specially paying attention to the mixture strength balance of the two cylinders (CO equal figure 3-6%) As a final practical test, alternatively disconnect the two ignition spark plugs, noting (using and auxiliary digital rev counter) that the engine rpm ratio decrease is repeated at the same figure.
Adjust the start opening screw ii) in a way to get an rpm rate of 3000± 500 n/1 with hot engine and starter totally turned on.

the main starting point is to see if the voltage is around 135mV (lowest) 150mV (preferred) 165mV (high) when the stop screws are backed right off.

If you are worried about doing the work yourself ...to reduce the shop time and cost why don't you take it in stripped of the fairing (on a trailer)
they will have added 1 hour either end for strip and re-assembly.

[torpedo51]

Thanks for the additional info.

I don't think you're appreciating my dilemma with the local shops here in L.A. I can afford a $300 service. I'm asking what the hours/rate is so that the shop doesn't screw me for additional work that I don't need.

I had a perfectly tuned 1988 750 Paso with no leaks or drips. Soon after I bought it, I took it to a reputable [non-Ducati] shop to give me diagnostic printouts for compression, leakdown, CO; I also asked for vacuum, specific gravity of the battery, brake disc thickness, tire tread, chain stretch, etc. I watched them do the work. It got a near-perfect score. I then took the bike to three dealerships in L.A. and asked each for a $50 pre-purchase inspection. I did this to establish a shop that I could use in the event of real problem. Here's what I got:

Dealer A: "Needs fuel injectors, coolant flush, chain and sprocket". No kidding. I verified the work order myself, and got my $50 back.
Dealer B: "Has cracked head, low compression - needs total rebuild for $1800"
Dealer C: "Dripping oil, needs new head gaskets, needs valve job and carb tuning, and brake system flush for $1100"

These are the three losers I have to work with for doing a throttle adjustment procedure on my 907.

[Laddie]

torpedo, Mate - yes I can appreciate your problem...

when I acquired my 907 it had a hesitation/miss at 4,000 RPM...it had just been "tuned" (according to the previous owner and receipts)
I called the shop that did the work - they said the 907 was "too complex" for them - but had charged him $800 for the effort.
I took it to the local Ducati shop - specifically for the engine hesitation; they repacked the head stem bearings as part of the work - and wanted me to pay for it...despite the bike still running like crap; then I got the story of needing to see the bike a few times because they're all different...

the shop rates are all different but if the bike is stripped this throttle re-set should only take 1 hour max. if they have the right gear.

[higgy]

any shop can't handle such a simple service and can't muster the required tools should be avoided.
Its just not that difficult and tools required are minimal. You can buy them yourself retail for about 20usd

[blazing928]

crikey we must be lucky in Melbourne, not only supposedly one of the best cities in the world to live in, but we also have the likes of Brad the bike Boy, about 15 mins from me and Mr Desmo, Bob Brown, Melbourne Desmo Centre, now semi retired about 1 hr away.
A few other main shops also get good wraps.

[torpedo51]

Update:

Turns out that the horizontal cylinder had a 0% leakdown reading. Once this was resolved with a basic valve adjustment, the idle was restored. We confirmed by performing a synch with a manometer.

All good now. Thanks for all the input - was very helpful to have all the information before making decisions on how to proceed