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vaughn

Little Help Colorado Guys

15 posts in this topic

I know there is much info about jetting all over this site but not a lot from 6500' guys. I have always had less than optimal jetting on my 01 YZ. I have stock jetting and have only played with the fuel screw to eliminate some decel popping. It seems to be quite temperature sensitive.

My primary concern is steady throttle at 1/4 - 3/4 turn. My bike sputters quite a bit. Wide-open throttle seems fine and off idle seems fine. After doing the BK mod it seems to have worsened the onset of the sputter. If my needle is too lean then this makes sense since the BK mod limits the fuel squirt from the 1.5sec stock to .5sec I have it set at now.

My confusion is the most people seem to run the needle one clip leaner. Being at 6500' should make my stock setting too rich already and going leaner makes seems right. I have this gut feeling that things need to be richened up at the needle though.

It is very difficult to do needle adjustments at home and test them out on my neighbors so I have to do it at the track where time is a premium and needle adjustments are the hardest.

Any local advice is appreciated and might save me much time. I want to ride not work!

-V-

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Jim H,

Just make sure they turn off the accelerator pump, otherwise an EGA is pretty worthless IMO, especially in the wrong hands. A friend of mine had a dealer “use” an EGA to “jet” his bike and WOW did they ever screw things up, he ended up paying them to make his bike run worse. This was in Denver though…

Vaughn,

I think you’re gut is wrong :)

I rode for three full days up at Rampart Range over the fourth of July, we camped there, so I had some time to mess with my jetting a bit. I’ve posted this several times, fairly recently, but I forgot under what topic or question. Anyway I got my ’01 YZ running pretty good with this combination:

EKQ (or EKR, I forget) #3 or # 2 (sorry, I should have wrote it down, but it is posted somewhere here)

38 pilot

160 main

1.5 on idle mix

~ 75 or 80 PAJ

I also have the modified accelerator pump. I think the sputtering you are feeling is due to overly rich needle clip, but a rich pilot could also have something to do with it.

The EKQ needle is the stock ’00 needle, and, compared to the ’01 EJP is two sizes leaner just off the pilot and a half clip position leaner everywhere. I have an adjustable Pilot Air Jet (PAJ), available from Sudco , or you can try the stock WR PAJ which is a fixed # 75 size. I could be wrong, but I think it runs better with the smaller PAJ, esp. if you go as small as 38 on the pilot. There is at least one other Denver area ’01 YZ owner around here who runs a 38 pilot (but he probably still has the stock #100 PAJ). The main probably matters less than everything else.

But before you buy a bunch of carb parts, I think you should try dropping your stock needle to # 3, and getting a # 40 pilot and see how that goes. Then try # 2 and a # 38 pilot, then spend the $12 on the EKQ needle if you are still a little fat just off the pilot. When we were up in CO my buddy’s ’01 YZ ended up like this - (EJP #3, 40 pilot) and wasn’t bad, but not nearly as good as mine.

Rampart Range is, I believe, around 7,500 ft. and higher, and I rode with the same jetting later on this summer at similar elevations down here in NM with similarly good results.

I normally ride at 4k feet, but quite a bit hotter than most any place in CO, and run the stock needle on # 3, & # 40 pilot in the summer months. Stock ’01 YZ is pretty good up (down?) here in the winter.

Hope this helps.

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Regarding Jim H's post: I can vouch for Paul at Apex.

Paul is a damned good mechanic and knows what he's

doing. He (Paul) also told me that every '01 426 they've

jetted is different and the EGA is the only way they've gotten

them right.

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Originally posted by Merfman:

Regarding Jim H's post: I can vouch for Paul at Apex.

Paul is a damned good mechanic and knows what he's

doing. He (Paul) also told me that every '01 426 they've

jetted is different and the EGA is the only way they've gotten

them right.

I believe you, but that last comment makes me wonder. I’m skeptical of ALL dealership mechanics, IMO for good reason, and I don’t think you need a sniffer to jet this bike. My friend’s ’01 YZ was identical to mine, and I haven’t had any problems with other guys’ WRs either (all ‘01s BTW).

For that matter I have run identical jetting in my ’00 and ’01 and they ran, well, identically.

Next time you see him ask him if he disconnects the acc. pump before he uses the EGA.

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I live at 6500 ft, Lake Tahoe.

Pump Fuel @91

Big Gun low end pipe

Main 162

Needle EJR #2

Pilot #38 @ 1 3/4

PAJ #100

Acc Pump @ 3/4 turn out from .3 sec.

Go to WR side search my posts, Topic: Jetting

by funktree.

------------------

Rick Fuller

'01 yz426

'00 yz426 destroyed by fire in desert race 4/22/01

'81 490 Maico

[This message has been edited by ricky1 (edited September 18, 2001).]

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vaughn,

I live in the springs area and had the same issues with my '01. Paul at apex was the only one to get it jetted right, he had to use a EGA machine but it now runs perfect.

Jim

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Thanks for the advise Hick and Jim_H. After rethinking I too have convinced myself the it must be lean. I went ahead and changed the main to 158 (because I had one) and dropped the needle 1 notch. I did a neighborhood run and is did seem to get better before till all the babies started crying. I'll likely wait to go leaner because of the cold weather coming and I do most of my riding in the winter. I'll print your post and save it for latter use though.

One thing, after moving the needle clip to 3rd position (leaner) I had to turn out the pilot screw to over 2.25 turns to eliminate some nasty decel pop. I know the engine wasn't fully up to temperature and I'll likley be turning it in some at the track once fully warm/hot. This makes me a little resistant to putting in a smaller pilot. Does this all sound right?

By the way. Rampart Range is closer 9000+' while Woodland Park is around 8465'. I get up there and ride Mountain Bikes quite often. It's a great place to ride.

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Hick, thanks for asking. I just got the adjustable PAJ, but that is all! ( no instructions). Where do I start with this thing? Do you know where to set it to equal #100, and #75, or just a baseline setting?

Thanks

------------------

Rick Fuller

'01 yz426

'00 yz426 destroyed by fire in desert race 4/22/01

'81 490 Maico

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ricky1

Tables never come out very pretty here but here goes, # of turns on the left w/ corresponding jet size on the right:

1/4 45

3/8 55

1/2 65

5/8 75

3/4 85

7/8 95

1 100

1 1/8 110

1 1/4 120

1 1/2 125

1 3/4 130

2 135

2 1/4 140

2 1/2 145

2 3/4 150

3 155

Here’s the link where I found this table, it is a very good Keihin FCR Jetting Guide.

BTW, when looking into the carb inlet from the rear, the PAJ is on the left, MAJ on the right. I think the article or whatever linked above has an explanation for why a lot of guys, myself included, ended up running w/out the MAH altogether; some guys even drilled it out, the thing is that #200 is the biggest MAJ there is and ALL the dirt bikes that run the FCR (DRZ, KTM etc.) have this size MAJ. Hmmmm.

Vaughn,

The popping on decel seems a bit weird, and you probably shouldn’t be more than 2 turns out on your idle mix, but I think you should wait until you can ride it longer, at normal engine operating temp.s, before making any judgments. Sometimes if you are too rich or too lean on the pilot changing the idle mix seems to give contrary results (or none at all).

I also think a smaller pilot sort of goes with the leaner clip position, but in the end you should go with what feels the best while doing the riding you normally do. Spending some time riding the bike with different jetting is worth it, IMO. Finally, when the seasons change down here (summer to winter, really ain’t an autumn in the dez, except for the dust storms) it is worth one size richer on pilot and clip on my 426.

Hope this helps.

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I believe a few other guys on this board with symptoms similar to what you describe (cold day, runs bad, put in a new plug and Voila!), although a bit worse (but opinions vary, don't they?), ended up replacing their CDIs.

If you have a willing accomplice with an '00 or '01 you may consider trying a CDI swap on a cold day at high altitude with a used plug and see what happens...

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Originally posted by Hick:

I<snip>

For that matter I have run identical jetting in my ?00 and ?01 and they ran, well, identically.

Next time you see him ask him if he disconnects the acc. pump before he uses the EGA.

Will do. FWIW, I don't trust 99% dealership mechanics

either. I've known Paul prior to his ToD at Apex though.

As far as your jetting, I believe you. I know what I've had to do

to mine though and the symptoms *sound* like a simple jetting

question but it isn't. The bike seems to be behaving very

strange at altitude and when the colder weather is prevelant.

I'm still waiting for the colder weather (20-30 degrees) to see

if my symptom returns. It runs great on a new plug but

absolutely will not start the next day until I replace the plug.

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Originally posted by Hick:

I believe a few other guys on this board with symptoms similar to what you describe (cold day, runs bad, put in a new plug and Voila!), although a bit worse (but opinions vary, don't they?), ended up replacing their CDIs.

If you have a willing accomplice with an '00 or '01 you may consider trying a CDI swap on a cold day at high altitude with a used plug and see what happens...

The problem is the willing accomplice. :) All my accompli that rode my 01 ditched their scoots and scarfed up their own personal 426's. FWIW, I first found out about this forum while looking for answers to that problem. I know it's a PITA but

I'll live with the occasional fouled plug for the performance.

What can I say, I'm easy to get along with. :D

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Update to my original entry that started this thread.

Went to the track tonight with one position leaner on the needle (3rd), leaner on the main jet (158) and 2 turns out on the fuel screw. In addition, my BK mode was set at .5sec fuel spray. Everything is all good. Bike runs better than ever with only the occational stumble off idle. I might try to get down to the .3sec fuel spray but I'm pretty happy.

Thanks Hick and the others that responded to my initial post.

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That’s great Vaughn, life’s too short to ride a poorly jetted bike (esp. when that bike is a 426). I think you should try a 40 pilot the next time you have a chance, I’m running that at 4k ft., it isn’t a huge difference but the response isn’t as good with the 42.

Caveats: It is likely warmer down here, and I have a more restrictive exhaust (FMF Q). But I think the pilot is worth looking into in addition to further adjustment of the accelerator pump.

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