Oh no, another jetting question - DVP needle vs ?



4 replies to this topic
  • dieseld

Posted January 31, 2002 - 11:39 AM

#1

In the year+ that I've been away from the forum, a lot has been done on these carbs and I'm just wondering what I can expect from the changes. When I first dialed in my trusty 98 WR, Clark was the 'Da Man' on this forum and by his suggestion I jetted as:

DVP needle 4th clip from top, 178 main, 48 pilot, 65 starter, 100 starter air, fuel screw 2 turns out - all this with YZ jetting, octopus gone, airbox lid off, and throttle stop cut.

I made this change at the same time that I went to YZ timing and the bike runs well, starts easy, and has never fouled plugs. But all this recent talk about E?? needles and APJ adjustments has got me thinking - am I missing out on something ?

The things that I do not like about the bike compared to stock jeting/timing:

- lots of popping when I cut the throttle and deccelerate at high RPMs

- the front wheel no longer climbs skyward when I snap the throttle in 3rd and 4th gear

Other than that, it has very smooth delivery, good torque, and revs out well.

So for you guys who maybe started with the jetting that I have now, and went to the new specs tested by Taffy, JD, and others, what did you notice ?

And since no jetting discussion is complete without it, I live a sea level and ride mostly between 0-3000', about 50/50 MX and desert. I'm racing Adelanto next month at 3000' and am hoping to dial it in beforehand.

thanks for any input,

Damon

  • Taffy

Posted January 31, 2002 - 02:20 PM

#2

the DVP has been swopped to a DMM for some. the narrower straight helps that first yard as you move off otherwise there isn't much difference. clip positions is about it.

the jetting you've got sounds rich on the main and low on the needle.

you could go down 5 on the MJ and lift the needle one clip.

the muts nuts in needles is the E series that JD "put us on to". although it started out as EKP it has gone more toward EKN or EMN (again for that first yard) and EMM like me.

we've also got pilot (re; slow) jets that are now screws so we can adjust. the Taff mod to your APJ is about 6 weeks old and the last thing i did before i sold it on boxing day.

good luck :)

Taffy

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  • James_Dean

Posted February 02, 2002 - 08:41 PM

#3

The DVP is what I sometimes recommend for very high altitude jetting. The needle is fairly lean everywhere.

To switch to an EMN/ELN/EKN will give more mid-throttle power (they are all the same except for clip position). These also are a step richer from 0-1/4 throttle due to the smaller needle straight diameter. EMM is another step richer from 0-1/4.

Why bother? The very 2 things you do not like now. A little richer from near idle(less popping on decel) and more rich in the mid (better wheelies).

The cost is under $20 (OCEMN needle and smaller main ~#170 from Sudco), and a some time adjusting to dial it in.

James

www.JDJetting.com

  • dieseld

Posted February 04, 2002 - 07:30 AM

#4

Thanks for the feedback Taffy and James. I think I'll try the EKN (since Yamaha dealer is by home) and a 168 or 170 main this week at the local track, but I'll make the switch after a few laps on my current setup to compare.

Any suggestion on a ballpark clip position to start with on the EKN ?

[ February 04, 2002: Message edited by: Damon ]

  • James_Dean

Posted February 05, 2002 - 06:39 PM

#5

If riding at a track, start with EKN clip #4. This may be perfect or, if slightly rich, then try clip #3.

James




 
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