Ducati Monster Forum

Moto Board => Tech => Topic started by: speedknot on December 17, 2010, 07:27:06 PM



Title: Choke or Fuel Enrichment Circuit?
Post by: speedknot on December 17, 2010, 07:27:06 PM
Does anyone know if my 01 M750 has a mechanical choke or a fuel enrichment circuit?  When I choke it I don't see the gate through the intake.


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: Howie on December 17, 2010, 07:37:09 PM
Most of us (including me) and Ducati call it a choke.  So do the Brit car people with SU CV carbs.  We are wrong.  It is indeed a fuel enrichment circuit.


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: speedknot on December 18, 2010, 07:13:55 AM
I'm not a big fan this set up.  A few of my other bikes had this and it just didnt work as well as a standard mechanical choke.  I had a hard time starting the Duc yesterday and I'm almost positive it was due to the carbs not getting enough fuel before ignition.  Other mechanics have expressed this notion as well.


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: Howie on December 18, 2010, 08:46:10 AM
Enrichment devices work just fine.  My bike starts in much colder weather than we are having without problem.  So did our 66 Volvo with SU carbs.  In cold weather, "full choke" is needed.  Check the cable adjustment.  Also make sure you have good spark plugs and good spark. 


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: koko64 on December 18, 2010, 02:39:00 PM
I'm guessing it gets very cold where you live as in snowing.

The enrichment circuit on the stock carbs is one of it's best features. My stock carbs fired the bike into life immediately in  zero deg C (as cold as it gets here which is rare). You have to have a good routine to start your bike that easily with FCRs in cold weather.

Give that carb a good clean and check for other reasons why you have hard starting. Like fouled plugs, old ignition cables, jetting not suited to your mods, weak fuel delivery, etc.

When it's very cold, do you have carb freezing also?


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: speedknot on December 18, 2010, 06:45:42 PM
My new garage doesn't have heat yet but it seldom gets below 40*.  It's insulated and attached to the house.  The carbs shouldn't be freezing.  I have a feeling the hard starting is due to it sitting a few weeks at a time.  I also had this issue with my XT225 until I changed the carb to a Mikuni TM33 pumper.  I checked the plugs on the Duc and its getting plenty of spark.  Weak fuel delivery seems like an issue.  
This is one of those mystery issues that I would spent hundreds for a mechanic to troubleshoot and never have it resolved.  I'll just chalk it up to a "temperamental european machine".  


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: ducpainter on December 19, 2010, 04:25:09 AM
My new garage doesn't have heat yet but it seldom gets below 40*.  It's insulated and attached to the house.  The carbs shouldn't be freezing.  I have a feeling the hard starting is due to it sitting a few weeks at a time.  I also had this issue with my XT225 until I changed the carb to a Mikuni TM33 pumper.  I checked the plugs on the Duc and its getting plenty of spark.  Weak fuel delivery seems like an issue.  
This is one of those mystery issues that I would spent hundreds for a mechanic to troubleshoot and never have it resolved.  I'll just chalk it up to a "temperamental european machine".  
Have you checked to make sure the cable is adjusted so it actually lifts the plungers and that the passages in the carbs are clear to allow fuel through the enrichment circuit?

My 900 starts at 32 if the battery is up to it at the time.


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: OT on December 24, 2010, 09:01:27 AM
FWIW - my 2004 M1000 (EFI with manual fuel enrichment) starts fine at sub-freezing temps.  Also stored in a ~40F garage with battery tender all winter....


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: ducpainter on December 26, 2010, 01:13:20 PM
FWIW - my 2004 M1000 (EFI with manual fuel enrichment) starts fine at sub-freezing temps.  Also stored in a ~40F garage with battery tender all winter....

The cold start lever on an efi bike only raises the idle.


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: speedknot on December 26, 2010, 06:29:24 PM
The cold start lever on an efi bike only raises the idle.
Smarty pants! ;D


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: OT on December 27, 2010, 11:34:08 AM
The cold start lever on an efi bike only raises the idle.
So, that's why it's called the "Fast-Idle Lever"..... :P

Frankly, I prefer having some semblance of manual control over this, rather than relying on sensors....


Title: Re: Choke or Fuel Enrichment Circuit?
Post by: ducpainter on December 27, 2010, 12:34:04 PM
So, that's why it's called the "Fast-Idle Lever"..... :P

Frankly, I prefer having some semblance of manual control over this, rather than relying on sensors....
Your bike starts at sub freezing temps.

Why screw it up?  ;D


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