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Discussion Starter · #1 ·
For search purposes. Hope this sheds some light for Dobeck users who have no Dyno resources.


OK if you can tune a carb you won’t have a problem with a Dobeck. I’m going to explain this while using carb logic.

First pot (like air screw/pilot jet): This one is the easiest. Start your quad and get it to operating temperature. While in neutral take it to somewhere between 1/8th and ¼ throttle. Start turning the dial richer (toward the bigger #s) until it starts blubbering and running rich. Now start bringing it back leaner. When it starts to clean up and run smooth stop. This is you’re setting for the first pot. Stab the throttle , if it boggs or pauses you might have went a little to lean…if it is slow to rev and puffs smoke you might be a little rich. Make sure you’re not judging the ¼ to ½ throttle area.

Second pot (like needle): This one you’re going to have to ride to tune. Start with the ballpark setting provided by Dobeck or one you got from one of the members. Again operating temp. Find a nice spot and take it to half throttle and hold it there for as long as the terrain will allow, if that’s miles then 10 to 15 seconds , at that time turn the motor off using the kill switch while holding it at half throttle. Check the plug color. Should be light tan. Darker richer, lighter leaner. Some time can be hard depending on your fuel (winter mix). I’ve found it harder to do as the years go on …I’m told it’s because of fuel refinement over time. If you care about details you can Google for plug color charts and fuel topics.

Third pot (Like main jet): Same process as the second pot but this time you have to hold it pinned. Don’t let it bounce off of the rev limiter. If you hit the rev limiter let off a little and hold it just under. 3rd or 4th gear, I like 4th

Fourth pot (RPM): this is the only part that does not resemble conventional jetting. This pot simply dictates when the third pot (main jet) kicks in and starts working. For my raptor the number of 9 Dobeck provided did not work. The light didn’t come on until it was getting ready to hit the rev limiter at full throttle. You want it to kick in right around ¾ throttle. You can do this while in neutral or riding.

Ride it around and take note of ridability. You should not feel any flat spots, should not blow any smoke other than start up(self enrichment). It shouldnt heat up, It sould not back fire other than a little exhaust gurgle in deceleration.

Other people’s numbers are good starting points but don’t rely on them to run you’re bike the same as theirs.

Here are some e mails between Matt at Dobeck and myself.

Sent: Wednesday, October 11, 2006 4:16 PM
Subject: Why 9 on the RPM

Hi Bill,
What I have seen since we developed the kit in 2005 is that the 9:00
position worked very well for general trail riding. But I have seen from are
9:00 to almost 3:00 depending on the modifications. Yamaha could of done
some fine tuning to there mapping that would also affect how the TFI
see's the main jet fuel. There's also manufacturing differences on Yamaha's
side and ours.
The settings that you ended up at should work very well. I do have one
question when you were checking to see when the red light came on, was it in
natural or while riding? It doesn't hurt to do it both ways.

Thanks
Matt

To: [email protected]
Subject: Re: Why 9 on the RPM
I checked for the red light while it was in neutral. My local guy gave my a setting they used on a 700r with similar mods as mine and they used a 4 O'clock setting on the RPM pot........which made my red light flicker at idle and when I would give throttle they all shined , puff some smoke and bog, this was all in neutral. On 7 is seemed very crisp and responsive and the red light kicked in a little before 3/4 throttle. On the test ride it seemed very responsive, pulled hard and I didn't feel flat anywhere but I didn't torture it to bad yet. Sounds like I'm ok at 7, just wanted to confirm with you since you suggested the setting of 9 in the paperwork I got with it.

Thanks for the info
Bill


You got it, that's how I would of done it.
Matt


NORMAL CONDITION
If the inner tip is dark-brown-to-light-tan color with slight deposits and slight electrode wear, with a slightly darker outer ring, you're in the ballpark.




RICH CONDITION
When your plug appears sooty black, with heavy carbon deposits, you are overly rich on the jetting. What can cause this? Rich air-fuel mixture, dirty air filter, excessive low speed operation, weak ignition or incorrect heat range.




OVERHEATING/TOO LEAN CONDITION
The tip and/or outer ring is light gray or white in color. Insulator nose blistered, glazed, cracked or shows signs of aluminum speckles, and the electrodes are burned. May be accompanied by an audible pinging/rattling sound, also known as a death rattle.
Possible causes include: Lean air-fuel mixture or air leak, incorrect timing, insufficient cooling, incorrect spark plug, heat range or improper spark plug insulation.


 

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Nice write-up man! :thumbsup:
 

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Could you please answer me this? I have heard it said here that the main limitation of the dobeck style efi is that you are unable to take away fuel. Is that true? Are the Trinity style controllers the same? They are a pushbutton style but I don't know if they operate on quite the same priciple.
 

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Discussion Starter · #8 ·
Since then I had it dynoed. Ron Wood,GYTR intake,Hot Cam II,JE 11:1, Dobeck Gen II, 3-8-7-8. Might be a good starting # for someone.
 

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Can anyone tell me if the pot settings from a gen 2 and the lights on a gen 3 are roughly the same? I.E. 5 on the pot is the same as 5 lights?
 

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If you make your settings anything less than what Dobeck has listed for all stock then you arent giving it less fuel or "taking fuel away".
 
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