Engine problems - irregular engine speed

Higgins

I am answering to myself.....
Today i visited a verry experienced mechanic. He was a Ducati dealer in the eighties and nineties. He received the first imported to France 851 from the factory at that time. So he knows verry well all the storry of the Desmoquattro. He is until now preparing alll kind of racing bikes.
He says that my bike is running normaly and the "roughness" at 3000-4000 RPM is perfectly normal for the 851 in his original setting.
Regards
Laurent

brad black

i'd replace the closing springs.

Higgins

Hi Brad,
According to your previous answer, I have ordered the 916 springs last month but one side is on back order in Germany (unknown delivery time).
So that is still on my wishlist and will do the swap as soon as possible. ;-)
Will keep you advised if any improvement.
Regards

stiglarsenDK

Check coils !

My brothers 888 w 996 had similar issues, after various route cause checks, he found one of the coils had x2 resistance .. after replacement no issues ,, worth a check !

Higgins

-35 chip Bin file

Hy folks as said two years ago in this same thread my 1989 851 S3 is still rough in the range 3000-4500 at very slight throttle.
After playing 35 years with a big fan over my head i am retired now and it is time to get down to business 😉
Job done on the 851 : New TPS closely adjusted, synchro, replacement of all sensors, valve adjusted at Brad specs, new fuel pump and regulator, new coils new spark plugs, new fuel filter and complete injector cleaning the Lady is still hesitating at low throttle (work perfectly at other range with a very good idle when hot).
I think I will start to play with Eprom. Actualy my chip is -009
I have read in Brad publication that a much leaner -35 chip has replaced the original -009 on later P7 851.
It would be very nice if I could get the -35 complete bin file here ? I cannot read XDF but only Bin.
If yes i will try to burn a copy on a new 27C64 Many thanks in advance.
Laurent

hindsight

Hi Laurent -

035 bin file attached

Regards,
Mike

035.zip

4.42KB

Higgins

Thanks Mike

Hi Mike, many thanks for your quick anwer, i appreciate very much 😄

First test ride with Innovate AFR sensor original -009 chip just to confirm starting point.
Verdict confirmed AFR 11,8 way too rich but only at low throttle.
At Idle and more opened throttle the AFR is correct.

To be continued 😉

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