A question on CO adjustment with PCV installed, stock CO #?

I picked up an 08' that came with a PCV installed. The CO setting was at "1". None of the original documents or instructions for the PCV were included in the purchase, and I'm having a lot of trouble trying to find out if the CO should be set to something else (with a programmer installed.) I've tried playing around with it to smooth out the "on/off" throttle, but can't feel the difference. It also seems to run hotter (on the header pipe) with a "richer" CO setting. When I put it at zero, the bike runs cooler and I swear the throttle roll on is smoother. This seems to contradict the general consensus which claims to see and improvement on throttle with a bigger number on the CO. If someone could point me in the right direction to a PCV install document I would be very appreciative. It's tough to try and sort out something out when you aren't even sure if it's set up the right way initially. Oh the joys of used vehicles

P.s. I emailed dynojet and received a dummy's guide to using google.... pretty much a bunch of links to the dynojet support page and a reminder that the program has a help menu. Neither of these things are install instructions...

Thanks!

sean

There has been a lot of conjecture and guesses as to what the CO number actually is, but I think it is a tuning tool for Yamaha's multi-cylinder bikes. It refers to the cylinder number (C1, C2, etc.). Since we have a single, it only comes up with C1. Sort of like balancing carbs, but it is used to balance the throttle bodies and injectors.

It also seems that each bike is different. It may be a calibration tool for the FI system to balance the cylinders, or to tune the engine from the factory. The consensus is that it only affects idle and just off-idle. I've played with mine a little and found it does seem like it affects throttle response a little (I have FMF tuner also). I would recommend you find the setting that "feels" best for your bike and don't worry about what everyone else is using.

Also, your PCV I think has the ability to affect fueling at idle and just off idle (FMF does not), so maybe it is set differently which makes your CO number different.

Here is the install manual:
http://www.revzilla.com/assets/0001/2445/power_commander_vfor_yamaha_wr250_xr.pdf

There are also a couple of youtube vids if you search.

Thanks for that link, dmmcd. Unfortunately there wasn't any information regarding changes (or lack of) to the factory settings. I can assume my unit was installed correctly as it works quite well.. And as far as the number being a matter of debate or uncertainty, DARN! I was hoping there would be some factory CO number I could at least start with as a baseline.

The CO does bring up the idle or drop it depending on the number used, and I think it's this raising of the idle that masks some of the on/off feeling the throttle has due to the stock TPS setting. I also seem to gain some seat of the pants power when the number is more into the rich zone, say 4 compared to 0

I am building up the courage to tackle the TPS sensor to clear up the ON/OFF throttle feature that our bikes seem to come with, at which point I probably wont feel the need to mess with the CO anymore

Cheers

I think you need to hook up the PCV to a computer to see what map is loaded. I have very little experience using a PCIII about 15 years ago. Once you connect it to a computer, you can load a pre-made map based on mods or what others have made from dyno tuning, or completely customize the fuel and spark map over the entire RPM range.

You can also unplug the PCV and put it back to stock...

There is no recommended CO setting for use with a PCV that I am aware of.  There are a number of things you can do with a PCV which will affect throttle response.  First you need to install the PCV software on a laptop.  You can download it here, there are also a bunch of maps, install instructions, and user manual(s) etc. all free:

http://www.powercommander.com/powercommander/powercommander_maps_installs_product_buy_options.aspx?mdlyrid=22-016&make=28&model=96&make-n=Yamaha&model-n=WR250X/R&year=2008&mk=28&mdl=96&yr=2008

You'll need a micro USB type cable to talk to the PCV.  Once you get that set up, as others have said, identify your map and make sure it is appropriate for your mods.  One thing I found useful was the to enable the accel pump utility, aids in throttle roll-on.  Mimics an accel pump from a carb. It's under the dynojet tools pull down menu (I think) and has a number of user parameter settings.  Also a throttle calibration, which if off can affect throttle behavior.

I wouldn't worry about the CO for now.  Get the PCV software up and running, familiarize yourself with it.  There are a number of things you can do to the maps like edit fuel at the 0% throttle column and so forth that will affect response.  

FWIW my CO was set off the charts by the previous owner, like 17 or something ridiculous.  I have it at 3 now IIRC.