2wheelover51 wrote: ↑Sat Mar 02, 2019 4:25 pm
Capitano, interesting that you mention the aftermarket pipes. This one (2012 model classic) had a new set of Cobras on, but when the original oxygen sensors were connected it didn't run right. Apparently disconnecting the sensors made the bike run ok but the FI light came on after 15 or so miles. I got them to refit the standard pipes and it's running fine, but I may put the Cobras back on in the future. When you say cold reset do you mean the ECU should automatically adjust itself to suit the pipes? The dealer (Steve) said he'd been told he would have to fit new (different) 02 sensors. I suspected it might need a power commander/remapping to cure the issue. I did notice the decent length cables as well as I will probably be fitting a set of higher 'bars.
Now you are asking me to delve back in time to actually working on at least 5 (maybe 6) VNs, the two 900s I mentioned, at least one each of the 1500 and 1600s and a VN2000. The VN900s were closest to my W800 in what we had to do so I'll try and be as specific if I can and apologise if I get it wrong. The 2000 was pretty specific anyway. It had a power commander when bought used, huge apehangers, and a darkside rear tyre!
Of the two 900s, the most common problem when putting aftermarket pipes on was the popping and banging on the overrun. This was as much to do with the secondary air injection as with the incoming fuel/air mixture. Both bikes had it bypassed in some way. We did one by plugging the hose that goes to the ECU-operated valve from the airbox, leaving it all intact. The second we did by a similar method to my W800 by fitting plates that replaced the reed valves.
I terms of correcting the fuel/air mixture, the stock ECU did a pretty good job with the set of aftermarket pipes on one bike, with just a cold reset (I'll come to that in a bit,) and they may well have been Cobras. Definitely an off-the-shelf popular aftermarket system for the bike, though. The second one had a custom made set of short slashcuts that were so obscenely loud, one of the guys (who normally likes loud pipes) made up a simple set of baffles for them. They were still loud and pretty much straight through.
With the latter one, the stock ECU was on the limits of coping , especially when the bike was cold. It misfired a bit and was still popping and banging excessively on the overrun, and not in a nice-when-it-does-it-occasionally way. A power commender would have been better, but we got hold of a plug-and-play version of the Cobra FI2000 and used that. Brilliant little devices that override the CU adding more fuel at low/mid/high range, set by potentiometers. I ran one (meant for a Harley twin cam softail) on my W when I had some opened up HD mufflers on it, and no O2 sensor.
On the one with the aftermarket system, it ran well with the stock O2 sensors and a cold reset of the stock ECU. This was achieved in the following way:
1. With the engine cold, disconnect the battery, and leave disconnected for at least 30 minutes (the time it takes a Prospect to make tea, and everyone to drink theirs and finish their stories
)
2. Before reconnecting the battery, operate the brakes, horn etc, switch the ignition to on while doing this, then off again. This is to get rid of any capacitive or inductive voltage in the system. It might be snake oil but it works!
3. Reconnect the battery. Start up the bike and leave to tick over until it drops the revs (ie the ECU drops out of cold-start mode). Don't rev it.
4. Take it for a ride and the ECU will start to relearn the characteristics of the new setup. It may take a few rides to get there but it will improve over a short period of time.
(I used the cold rest on my W with a Motad aftermarket system fitted and it works perfectly with the stock ECU and O2 sensor)
On the VN900 with the open pipes, we took off the two O2 sensors and replaced them with eliminator plugs. You could make your own as I have the resistor values for the one I used t do the same on my W and that was a VN900 one originally. That one used more fuel overall than the one with the stock ECU/O2 sensors. hat was what we expected. The pipes that were made for it didn't have the bosses for the sensors anyway, but if you were doing the same with a stock or aftermarket system, a short bolt and copper washer do the trick.
We never used, nor even knew about, fitting different O2 sensors. That's not to say it isn't a valid option.
I hope this helps, because potentially you have a great bike there. I rode Harley Davidsons for 15 years and have no beef with them whatsoever. If I was returning to riding big cruisers though, I'd look no further than a used VN.