rich or lean?



12 replies to this topic
  • larsonsenza

Posted May 28, 2003 - 03:38 PM

#1

Im still confused if I need to go leaner or richer. With the obeln needle #3 I am getting a studder when I get on it only in first and sometimes second gear as the rpms increase, but when I shift into 3rd,fourth and fifth it flies with no studder. I tried to see at what throttle position the studder was happening, from what I could tell maybe it was a quarter open or somewhere around there. Its hard to tell exactly. I tried clip 4 with smaller mains 162 and 160 and it ran worse, more studders. I tried clip two with a 168mj and it just seemed slower, studdered also. clip 3 by far feels most explosive. I put it back on clip 3 and tried a 40 pj and a 45pj. 45pj ran terrible and 40 seemed a little slow to rev. The pj screw was about 1 out on each.

So I'm back to obeln #3, with stock settings and not sure were to go from here. I ride in Gaylord Michigan, I think Im around 1000ft with mods in signiture. From looking at older posts, Im just getting more confused. With the uncorked pipe and air lid removed you would think things would be leaned out, but when I went to clip 4 it jsut ran like hell. Also when I start my bike cold I can pull the choke in right away and it will run. Is that a sign of rich pj. Any help would be greatly appreciated.

  • Hick

Posted May 28, 2003 - 04:15 PM

#2

How does it run with a 42 pilot?

Is that what you had in there to begin with?

One thing I see is that you are making too many changes, so you can't isolate what any one thing is doing.

This sort of causes the second thing, which is that you've tried everything and the stutter was still there, so maybe it isn't a jetting related issue.

  • wrkaholic

Posted May 28, 2003 - 08:31 PM

#3

I do not know anything about your needle, but, it sounds rich on the pilot jet to me. I am no expert. :)

  • LarryCO

Posted May 29, 2003 - 04:18 AM

#4

I just moved up to MN a few weeks back from CO...threw in the following at it seemed to run fine (see below). Havent had an opportunity to experiment yet, but it seemed pretty close...have some more learning to do since I've always been at altitude until recently... :)

38PJ/65PAJ/EKN#4/160MJ/160MAJ/1.0 turns fuel screw.

You might consider playing around with your airjets...as you didnt mention what they were (it's not just the fuel jets that matter). I run a 38PJ/65PAJ combo on the pilot circuit...a 35PJ/50PAJ or 40PJ/75PAJ should work as well...

I know that there's quite a few folks running a 35PJ/50PAJ/EMM#5 around, but they're at sealevel...and I dont want to tout a setup unless I've had a chance to try it myself. Food for thought...

Larry"MN"

  • larsonsenza

Posted May 29, 2003 - 08:53 AM

#5

My starting point was all stock (42pj) with a obeln #3. Never touched the paj throughout testing. That seems to be best setting so far. I would like to get that studder out though. I was wondering if I corked up my muffler and took it for a run, if it made things worse it would be to rich, if things got better to lean, am I right. Also, is there any truth to starting your bike and shutting off the choke right away and if it still runs your too rich. The warmer it is out would it still work.

I was looking at older posts and found that the ekn needle is a half a clip leaner than the eln. So if I was on clip 3 with ekn, it would be like clip 2 and a half with obeln. I was thinking of trying ekn.

  • LarryCO

Posted May 29, 2003 - 09:59 AM

#6

My advice to you would be to try one "circuit" at a time. Start with the pilot circuit (affected by the PJ, PAJ, and needle diameter). Try this test:
- Wide open in 4th gear, then let off the throttle. Check for either backfiring, popping, or none. If backfiring, PAJ is too small for the PJ...if popping, PAJ is too large for the PJ...if none, then you've got a good PJ/PAJ ratio. I suggest the Sudco adjustable pilot air screw...as you dont have to buy PAJ's anymore...$15 for the screw covers all the PAJ's you'd ever want to throw in there. Find their 800 number to order...

I think the "N" needle should be about right...so I'd concentrate on the PJ/PAJ ratio.

Once you've got that down, play with the needle/clip position. BTW, you've got it backwards regarding EKN vs. ELN. EKN#3=ELN#3.5 ...the EKN distance from top of needle down to where its diameter is 2.514 cm is slightly less than the ELN...so you have to "raise" the ELN needle slightly more by going up 1/2 clip position (to 3.5 in my example).

Anyway, at mid RPM's and constant throttle, check if the bike is "surging". If so, you're too lean on your clip position. Also, if mid RPM acceleration is sluggish, you're too rich on clip position. When doing this, keep the MJ constant, as it has an affect on mid RPM's.

Then, verify the high RPM's the same way as the mid RPM's to test your MJ. If you change your MJ setting, you'll have to go back and re-test your mid RPM's, as you've just changed that circuit somewhat.

Finally, figure out what MAJ works best. I found that my bike accelerates faster (rev's out faster) using a 160MAJ vs. the stock 200MAJ. Not a biggy here, just personal preference.

Anyway, that's what I would do. I can say that what I have is somewhere in the ballpark...so perhaps start there. Our bikes are setup very similarly (see my sig below)...except that I've done the BK mod to get rid of that 1/4 throttle bog.

FYI, you dont necessarily have to buy another needle to switch from ELN to EKN...just go find a very small, thin washer...that's about as thin as 1/2 clip position on a needle...and you can use that to raise the needle to equate the two. Or just buy another needle... :D

Good luck! And keep me posted on what works well for you...as I'll be having to do the same testing here soon when work calms down for me and I get some time... :)

Larry

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  • captain_S

Posted May 29, 2003 - 10:48 AM

#7

Look inside an old car tape player for that washer! :)

  • larsonsenza

Posted May 29, 2003 - 04:55 PM

#8

Thanks for the info. It will be a couple of weeks before I get back up north to do more testing. When you talk about the pj/paj combo, do you mean to replace the paj instead of pj? Also is the poping sound when running lean really loud and distinict like a backfire. What exactly should I be listening for.

  • Hick

Posted May 29, 2003 - 07:36 PM

#9

Thanks for the info. It will be a couple of weeks before I get back up north to do more testing. When you talk about the pj/paj combo, do you mean to replace the paj instead of pj? Also is the poping sound when running lean really loud and distinict like a backfire. What exactly should I be listening for.


PJ/PAJ: Not sure what your question is exactly, but the two jets sort of go together. I think what LarryCO was talking about was the tendency for the Air Jet to really affect higher rpm jetting, but you also need to realize that if you change the fuel jet more than a size or two you will likely need to change the air jet in the same direction (larger-larger or smaller-smaller, they go together). So, if you have the best off-idle throttle response on the planet, but you are besieged by annoying popping on decel you need a smaller air jet (low throttle=pilot circuit, the fact that it is a high rpm problem only means it is air jet, therefore it is Pilot Air Jet).

The popping we are talking about is a common thing with a modern thumper. If you want to get technical it is a backfire, but it sounds like a series of popping noises that vary in volume. A few here and there is normal, but if your bike always pops, and pops a lot under decel, and you are happy with your idle and pilot fuel mixtures, then the PAJ is what you need to be looking at. For guys like me and LarryCo at higher altitudes and therefore smaller pilot fuel jets this is an issue we were very happy to get sorted out(at least I was).

Hope this helps.

  • Taffy

Posted June 02, 2003 - 06:25 AM

#10

i'm going to guess that he has very little backfiring/popping and that it's stinking rich at 1/4 throttle. that's pilot jet country!

so i would blow out the jet that you can see in the front face of the carb marked #75 or #100 (the other one says #200, so that's how you know!) the take the carb apart and do the lot obviously. when you put it back together try the PS underneath first at 1 turn from closed and then 1.5 turns.

this all might help. the next stage is to go down two PJ's if it made no difference.

by now we should be getting a clearer picture and so report back here with your findings.

Taffy

  • captain_S

Posted June 02, 2003 - 11:47 AM

#11

To help you with throttle position,put some duck tape on the cable housing and some on the throttle grip(put a strip on then cut down between the housing and grip with a sharp knife).Now mark a line accross them for closed throttle position,then turn the throttle full open and mark another line on the cable housing side where the mark on the grip stops(full open) the then mark a line for 1/2 throttle,1/4 throttle,3/4 throttle,and you should find this will help you take some of the guess work out of what position the throttle is at?(it gives you more time!). :)

  • larsonsenza

Posted June 02, 2003 - 01:42 PM

#12

Thanks for the info. It will be a couple of weeks before I get back up north (were bike is) to test. I will post from up there on what happens. One more question, if you could turn the pj screw all the way in without stalling the bike or making much difference at all, you need to go down right, but then you need to change the paj with that. So if I had to go down to a 38pj, I would go douwn from 75paj to ? Also would going down on the pj be because of the obeln needle?

  • Taffy

Posted June 03, 2003 - 09:25 AM

#13

a 38 Pj needs about a 60 PAJ and a 35PJ needs a 45 PAJ. the needle straight can slightly alter this if you're at an extreme code but N is in the middle of the game/rich of centre (if P is lean of centre) so a 38 or 35 will be lovely.

Taffy




 
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