David Platt short exhaust 2004

Paul Bryant said:

Allan, how can the O2 sensor access outside air at any throttle position ?
The DP system is an add-on after the stock header, the O2 sensor is situated in the tail end of the Stock header.

Click to expand...

As I think I mentioned to you in an earlier email, I have been getting help for my MAP from @Ulf Penner. He sent me a fantastic map for my setup that changed the way my bike ran completely- It was like fire had been breathed into it. To perfect it and get it ready for your exhaust system, we decided that I would put a PCV and AT on. I did the install really easily and used his map as the underlying map. We started the PCV with a zero map as the stock PCV ones weren't close enough to my setup and let the AT do its work. After a ride where the bike ran fantastically well I came back and checked the tables. I accepted the trims (a lot of which were very high 15-20) and rode again. This time there was spluttering and lumpiness at lower throttle settings. I came back , accepted the trim(high again- which should have warned me) . Next time I rode the bike was un-rideable. Stalling on pull off and black smoke and backfiring when It didn't stall- and beautiful at higher RPM and throttle settings. I sent the trims and tables to Ulf and after checking there were no leaks in the exhaust we zero'd everything and started over with a slightly modified base map and a zero PCV map- target table remained the same. Bike flew like a homesick angel.
I attached my laptop and ran the motor. Looking at the live PCV fueling reading on the right side, under Ulf's direction I blocked the right hand exhaust with a towel and watched the reading. It changed bigly; as soon as I removed the towel from the right exhaust it went back to where it was. That let us know that there was a change in the reading at the sensor when you prevented it from "seeing" the air that was sucked back into this very open system. We set the fuel table and trim table to zero then set all cells below 40% in the throttle opening columns on the target tables, forcing the AT to ignore readings at lower throttle settings and to rely solely on the map in the ECU. Have ridden about 1000km since and the bike runs really beautifully. The trims in the higher throttle settings are relatively modest and so I haven't accepted them yet. The plan is to get a good read over time at the higher throttle settings from the AT and then to extrapolate those trims back to the lower throttle settings at which time I may remove the PCV and AT.

Ulf Penner has been an invaluable help in getting my bike to run the way it does. I "swapped " bikes recently with another Rocket owner here for a few miles and he couldnt believe it was the same bike as hi. The difference is remarkable considering he has TORS and Ramair but no Penner map or PCV.

Right now I'm happy with how its running and a little disappointed in the AT performance but its not the sensor that is at fault. Power Commander help desk agreed with Ulfs assessment and suggested that perhaps moving the AT O2 sensor closer to the motor from where it is (although it doesn't look like it would fit easily) would probably help. I was thinking that probably around the bend in the middle of the DP crossover would be a good spot that would keep it out of the way and away from the opening of the right exhaust enough to make a difference and allow it to do its work properly.

What are your thoughts?

It's great that @Ulf Penner has been so helpful Allan, Ulf is the sort of person (along with a few others here) that we need.

What I couldn't understand was the O2 sensor have access to outside air, as you say it is that the air is being sucked back in due to a very short system. (Personally I have always thought that those DP systems were way to short)

In the end you got there, you've gain some great power and a little knowledge along the way.
All very interesting reading.

It is defintly a problem, that the wideband-sensor is reading too much oxygen at lower revs and throttle opening.
As there is a pressure pulsation in the exhaust, it always breathes outside air. The more open and the shorter the exhaust is, the worse it gets.
And it mainly happens at low revs and loads.
Suggesting that the gaskets are tight and the O2 sensor works correctly, that is my only explanation.
But I never had a case as bad as this one even with shorter exhausts.
Any input is welcome.

Penner said:

It is defintly a problem, that the wideband-sensor is reading too much oxygen at lower revs and throttle opening.
As there is a pressure pulsation in the exhaust, it always breathes outside air. The more open and the shorter the exhaust is, the worse it gets.
And it mainly happens at low revs and loads.
Suggesting that the gaskets are tight and the O2 sensor works correctly, that is my only explanation.
But I never had a case as bad as this one even with shorter exhausts.
Any input is welcome.

Click to expand...

Hi Paul sent me this link via email (haven't been on too much recently). I deal a lot with hydraulics for work and we use a lot of venturi systems.

Consider this.

There is not only gas wave, but a pressure wave in the pipe (exhaust). The pressure wave will be travelling at the speed of sound, the gas somewhat slower. If you have twin short exhausts and they are pretty much open pipes. Flow always takes the easiest path. It may be that the pressure wave is travelling down either pipe randomly and "directing" the following gas flow creating a venturi on the other pipe, it may be constant, or may be changing, but air will be being sucked into the other pipe and if the O2 sensor is close it will pick it up causing the lean reading.

I had an old magazine somewhere on vintage race bikes and how they sized the length and diameter of the megaphone exhausts and they were concerned with both the pressure and gas wave as the pressure wave was used for scavenging the cylinder? or something like that.

I found it important not to accept too many trims on the PCV AT as it eventually leans out the motor down low due to the additional fuel shot from the ECU when you twist the throttle. Think you advised me of this. Since I've reset its been beautiful. Have been playing with adding and removing fuel with the POD-300 recently and monitoring the AFR. Seems a little more fuel in the mid range has improved the bike. I am nervous to adjust the timing though.

Thedogsbollocks said:

Thanks again for getting into this Guys as there is a bit of misrepresentation by DP when marketing these pipes ( ie 12 min tune and good to go...yeah right!)

So , I’ve ordered the PCV. Going to order Ramair ( or H&N...what best?). I’ve searched google and cannot find this intake kit?
So this will leave me : DPs / Ramair / PCV. Now the 500th question ()...Can anyone send me a great tune for this set up?
Seems like this will catch me up with some of you Guys that are really happy with this set up once you found the right tune.

I have the ‘ new tors tune’ ( the tune for V&H the dealers now use as a replacement as the Tors not available). Can I simple load a map into the PCV and off I go once air fitted. Or do I need to somehow reload the original map the bike came with ie the standard non tors map. Hoping I can just install air and PCV ( now I’ve bought it) with the right map and put the whole ting behind me.
Thanks again everyone...Cherrs!

Sorry , one last thing...any merit or advantage adding the auto tune...if yes might as well jump in all the way?

Click to expand...

Hi as per my other comment on this post I have been off line a lot recently but Paul sent me this link.

Ramair or K&N both are good just personal preference. If you order the PCV you need to get the AT for it as well otherwise its not much use. If your budget allows the POD-300 is gold as you can monitor and adjust the AFR on the fly.

For the PCV you should really have a good ECU tune first IMO as the PCV is only a piggyback interrupting the injector pulses, it does not affect the F/L switch, sec throttles or (most importantly) ignition timing. (There is a PCV ignition module but it costs more than the PCV).

The "new tors tune" I would be dubious if that would have fixed your issues as its still pretty close to stock.

If you PM me I will send you the K&N part numbers if that's the way you want to go.

I've not had any experience working on a bike with Dave Platt systems but the "12 min tune and good to go" is a joke. The 12 min tune is only for idle as the O2 sensor is a narrow band it will never adjust the bike for over run when you com off the throttle suddenly. If you PM me let me know your bike year on VIN no I'll see if I have anything that may help.

Penner said:

It is defintly a problem, that the wideband-sensor is reading too much oxygen at lower revs and throttle opening.
As there is a pressure pulsation in the exhaust, it always breathes outside air. The more open and the shorter the exhaust is, the worse it gets.
And it mainly happens at low revs and loads.
Suggesting that the gaskets are tight and the O2 sensor works correctly, that is my only explanation.
But I never had a case as bad as this one even with shorter exhausts.
Any input is welcome.

Click to expand...

The 12 minute tune thing annoys me.....

Hi Sleeves,
Would you have a ECU tune that would help with a 2004 and the DP shorties? anything better than the Tor tune. might also look at a Ramair intake if that helps?
Cheers

sleeves said:

The 12 minute tune thing annoys me.....

Click to expand...

And me too !

There's Guys out there that change the Exhaust and do the "12 minute tune" then say it's great, quite honestly, they wouldn't have a clue!
As for some one selling a system and saying that a 12 minute tune is all that is required ...... !

Which DP shorty system are you speaking of? Just to be clear for all...
The outlaws that just come out from under the frame, or the shorties that come back to the shock bolt?

WyldCFH said:

Which DP shorty system are you speaking of? Just to be clear for all...
The outlaws that just come out from under the frame, or the shorties that come back to the shock bolt?

Click to expand...

Mine go past the shock bolt not outlaws