Main Jet?



4 replies to this topic
  • MotoGreg

Posted August 27, 2000 - 02:53 PM

#1

I notice that everyone runs a big 178-180 so I tried it about six months ago and didn't like it so I went back to a 172 (stock was 168). I recently switched from e-series to DSP exhaust and figured I'd give the bigger jet another try so I did today. I only rode a few laps before I had to pull in and switch back to the 172.

The bigger jet just feels... I don't know, kinda flat. With the 172 the power is very crisp and clean and even the exhaust note has a very sharp bark to it. The 178 feels flat and lazy, it doesn't leap forward, and even the exhaust note is kind of a slow rumble rather than a sharp bark. I know everyone here runs the bigger jets, but has anyone else really done any back to back comparisons? Is it just my bike?

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MotoGreg - The voice of absurdity
'99 WR400 - 'Cause thumpers rule and two-strokes drool!
'92 GSXR 7/11 (But I wanna get a dope 916)
I might let you visit my photo album for $3 - ENTER AT YOUR OWN RISK - DANGER LURKS WITHIN

  • Clark_Mason

Posted August 27, 2000 - 05:12 PM

#2

Yo Moto Greg

What needle and clip position are you running??

Clark

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  • MotoGreg

Posted August 27, 2000 - 08:16 PM

#3

OBDXM needle (came stock in my Canadian bike) on clip 4 (one position richer than stock)

Is my needle a little richer than the USA spec bikes? Did the US bikes come with the 168 as well?

------------------
MotoGreg - The voice of absurdity
'99 WR400 - 'Cause thumpers rule and two-strokes drool!
'92 GSXR 7/11 (But I wanna get a dope 916)
I might let you visit my photo album for $3 - ENTER AT YOUR OWN RISK - DANGER LURKS WITHIN

  • Clark_Mason

Posted August 28, 2000 - 06:15 PM

#4

Moto Greg

The DXM needle will start its taper later in the thtottle opening sequence and therefore be ever so slighly leaner on the main jet when compared to the US stock WR DTM or YZ DVR needle. If you are YZ cam timed I would recommend you drop the DXM needle in favor of the DVP (#4) especially with the DSP exhaust. If you are WR timed with your DSP exhaust then run the DXM in the #5 or #6 clip and a mininum of a 175 MJ.

Clark

  • Gary_Kessler

Posted August 29, 2000 - 07:43 AM

#5

Moto Greg -
If you're YZ timed, get the DVP needle!

With Clark's prodding, I did and it TOTALLY changed the way my WR responded and how my DSP sounded. More bite in the mid-range and the high end is excellent. I gives the DSP a sharper tone. . .it's noticable.

I ride at 5300 ft with PJ=48, MJ=178, DVP#4 and PS=1.75 and it RUNS great! Airbox lid off.

You can order the needle from BajaDesigns @ (858) 578-9111

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'00 WR; YZ modified, DSP exhaust system, UNI air, Dunlop D756, ProTapers, Devol Rad Guards, P-38, Mason/Dean Jetting specs. . .and lovin' it!




 
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