Can't contain my curiosity any more. I've been hearing for a long time about Magneti Marelli systems being garbage so I'm asking for people to chime in and tell us exactly what is the problem with MM fuel injection systems???

 

It`s not that they are garbage
The problem is parts are getting hard to find and people conversant with repairs are even more rare

 

I have a RK Classic with MM, it starts easily and runs great.
The only part I know of that is difficult to find is the ECM… there are always several available on eBay ($350-$500) from folks that have converted to carb.

You can buy one, change it out (so you know it works), and have a spare as insurance.

 

Doesn't someone make an aftermarket ECM?

 

Agree with eighteight and would add the finding tuners that are familiar with the MM system are also hard to find. As long as the bike stays stock and the system holds up owners never experience these problems. However, if performance upgrades are planned, most going that route will convert to carb or Thundermax.

 

I have had no problems with the MM system. To be prepared a bit, I have purchased some replacement sensors to hedge against the day that one of my sensors might malfunction.
In my opinion, the MM got a bad rap because it was not something that the average shade tree mechanic could not work on. After that, the bad rap has remained as urban legend.

 

This, and it came out about the same time that everyone was screaming that robots where going to take their Jobs, hence evil technology.

Simply put, take the time to learn it/ how to wrench on it, and its not a problem. And trust me, little lucas fuel treatment in the fuel from time to time to keep the fuel system clean, and it will not be like a carb that your pulling apart every 4 years to rebuild (or at least clean) instead.

 

[QUOTE=GOGOBECK;21858499]I have a RK Classic with MM, it starts easily and runs great.
The only part I know of that is difficult to find is the ECM… there are always several available on eBay ($350-$500) from folks that have converted to carb.


Anyone have ideas about these two springs? I finally got my idle corrected, fuel leak repaired, and fired it up. Runs like a dream. Go to take it out, now the throttle sticks. The small spring on the bottom has been gone for as long as i know, but the big cam lever spring might be going. Runs great up to 2nd gear, then craps out.

 

If I understand how ECM are programmed you would need to obtain a used ECM that was programmed to the bike's state of tune.
My bike is a Screamin' Eagle II so I would need to obtain a used ECM that came from a bike that originally had the Screamin' Eagle II tune installed. A bike that had a Screamin' Eagle I tune needs to have an ECM that was programmed for that level of tune. If a bike was just stock tuned it would need the ECM for the stock setup.
This requirement of a pre-programmed ECM is necessary because you can no longer get the H-D MM program card for the different levels of tune. The cards were a one-time use.
If I am wrong, please chime in.

 

The 97 & 98 ecm's are programmable, 96 is fixed. A stage 2 SE is only the rev limiter being raised by a flash cartridge, fuel addition is coming from red injectors plus SE3 cam using the same map, so don't look too deeply into this. If you need another ECM wanting the rpm's raised for a little more fuel a Power Commader is simple to use once getting past stage fright.

Your SE tuners on the newer bikes lock into the ecm and mated for a 1 time use, that M&M is a prehistoric spray but simplicity has it's place in the real world.