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Jack's Mod and a Cobra 2000

5 posts from 4 voices
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  1. KjBigerBoj

    Anybody running a jack's mod with a corba FMS? If so, what settings are you running on the FMS. I tried to search this but could not find any specific threads so I apologize if this has been asked/answered before. Had it set to about 3-6-3 but gas mileage terrible but did run good. Set it back today to 0-4-0 and still ran OK (did not test the upper end) for 30 miles and no idea on gas mileage. Some FMS only threads suggested 2.5-3-3 so I will try that. Any other suggestions would be appreciated.

  2. Driwetapisnezz

    Many have struggled to find the "right" settings for their bike. Things like gas are different state to state, people are running different blends of modified or aftermarket intakes and exhaust. I know several guys who run 2.4.2 (or close to that).
    With the breathing opened up I don't think you gain a lot by bumping the settings up beyond that. I would of course defer to Morg, Shane SS Custom Cycle and the other forum Guru's.

  3. Jibby87

    I am running mine at the Cobra recommended 1/3/1....and it is performing great. I know some on here are experiencing good results with higher settings.
    I talked to a tech at Cobra who told me 1/3/1 is their recommendation for the 1300 with my pipes, and that I wouldn't need to go higher if the bike was running good at those settings.
    I WAS getting mid to upper 40 mpg before installing the pipes and FMS, but was also getting the hesitation in lower gear. On my last two tanks I only got 40 mph. It seems to me that adjusting the pots richer would only retard my mileage further.

  4. MorkKW

    Hey KBB.

    I've been running with the Cobra FMS a long time, also with Jack's O2 Mod since right after he first introduced it.
    NOTE: thzg O2 Mod will work "only" with a "Closed Loop" FMS. If you have an "Open Loop" unit, get rid of the O2 Mod as it can do you not an iota of good.

    My bike is "dialed in" right on the money "for me," meaning it's set up perfectly for my specific mods and how I prefer my bike to run considering how and where I mostly ride.

    Even when all things appear equal, they aren't necessarily so....referring as an example to muliple bikes that have oyal-star-tour-deluxe\" class=\"ymln\">the same FMS unit and the same exact mods. With the pots set the same, not necessarily with the bikes perform the same way, nor might the rider prefer whatever results are found. Riders and they likes & dislikes vary just as bike will vary. There are many variables involved.

    Starting with your settings, I'm a little confused considering your settings, but it sound as if you also do have Jack's Mod. (We'll save most of the O2 Mod coversation for a later day.) Your bike is the very first I know of using settings of 3-6-3. That will normally produce results that you won't like or enjoy under most circumstances. Secondly, moving them to 0-4-0 won't accomplish anything good and won't make you a happy camper, or your bike a happy Yamaha. Adjusting pots to "0" moves the fuel mixture back to its factory settings in those specific areas otherwise controlled by those pots. and your most recently discovered settings of 2.5-3-3....well, it may be "better" than your earlier exaggerated settings of 3-6-3, but it's very doubful that they will be very efficient.

    I'm only presuming here that, due to your high settings with your 1st pot, you must be using an "Open Loop" FMS. Is this correct? Otherwise, with a "Closed Loop" unit PLUS Jack's O2 Mod, you would want to set Pot #1 at either 1 or 1.5. Jack's Mod, alone, will automatically be raising the fuel supply beyond what's generally called for by the bike's ECU as it relates to the fuel supply contolled by pot #1.

    I apologize because I can't make any other suggestions...yet. I'm unable to effectively prescribe any proper medication since I've not yet seen the blood results or xrays. In other words...
    1. What mods have you added to your bike?
    2. In what type of conditions and at what altitude do you ride.
    3. Are you primarily peferring performance, economy, or both.
    3-a. If both, is your preference for the results to leaning more heavily towards the performance side, or the side that would provide better economy?

    These question may all sound a little silly, even to the point of them almost being overkill. But know that you do have a choice in the matter when setting up your FMS. It really depends upon your own individual preferences. You actually can control the outcome, at least to some extent.

    Next, rather than to take up lots of space here in the forum, which I've already done and without accomplishing much at all, if you're interested, you're more than welcome to send me an email and we can discuss all of this much more in depth....but again, only if you wish. In one moment, I'll be sending you a private message with my email address.

    Be well - and safe.

  5. KjBigerBoj

    Appreciate the response. only mod is a drilled stock exhaust. I do have the closed loop unit. I cut the #1 dashpot back to 0 on the premise that the Jack's mod was indeed dumping in more gas. In the limited driving I have done since changing, I can tell no difference. I cut the #2 dashpot back to 4 to try to improve gas mileage. I cut the #3 dashpot back to 0 because I rarely ever run full throttle and I understand that #3 only kicks in under heavy throttle. Full throttle always seems to be OK anyway. I know it takes playing around with to reach optimum but I was just hoping for a shortcut. Jibby87, I will try the 1-3-1 if it ever quits raining here and see how that works. I just hope to get to a place where the bike runs without all the jerkiness and still gets reasonable gas mileage (+/-40 mpg). Thanks again for the input.


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