Hate to do this... but jetting problem

Setup: 21 del, e50, hacked estoril, 65metra, b7hs plugs,

Hey Guys, I know I'll probably get links to the wiki article but this one has me kinda stumped...

I've run this setup for quite a while now, with good results, blasting off the line, hitting low 50's, and it hasn't really given me any major problems since I built it in last october, until now...


jetting was 90 main 50 Idle. clip at leanest setting

Ran this jetting for quite some time, it was always a little rich on idle, with the mixture turned in intil It couldn't go anymore, but with slippy clutches, it just revveed through the hesitation and I was too lazy to actually change it out.

Bike suddenly began to cut out and die down at 40+, only to resume again after slowing down a few MPHS. plug chops look good.

Tried: adjusting plug gaps, new plugs to no avail.

I know alot of yall may be thinking I should be running B8hs plugs, but the 7's have been doing really well for me so far, for months and months, and I even tried b8's with no success. I'm pretty confident with B7hs's for this setup.

Tried: re-jetting up to 92, (don't have a 91)

Result: no longer cutting out at 40, probably hitting about 50 at 3/4 throttle , but fourstroking heavily at full throttle and more hesitation from idle. plug chops still look good. Overall bike is very rideable and performs well.

-so then-

Tried: Actually replaced Idle jet for a 45, hoping to better the off the line response and slightly lean the top out.

Result: Off the line ok(not great seems to hesitate still no matter how I turn the mixture) now but through half throttle sucked(chopping in and out), and WOT still sucked and rich. Tried enriching the needle, only worsened the situation. Could not get a good plug chop because the bike was chopping in and out too much. Overall bike was unridable.

-so then-

Tried: Put the #90 main jet back in,

Result: top end good now, best thus far. low end sucks now. choppy throughout riding the needle. placed it back in the leanest setting. Better but still cutting in and out a bit.

The Confustion: Immediately upon upjetting, for the most part the bike was running good throughout the midrange, but suffered from over richness on both ends, and solved the immediate problem I had from the bike dying at over 40. But now I'm back at pretty much the original jetting except the smaller idle jet, Which would mean that the top end is actually leaner now than I began with, and it now has the most usable top end. When trying to compensate for the smaller idle jet by enriching the needle settings, I only made the cutting in and out worse. Originally, Midrange was awesome, now I've leaned the idle out, but can't seem to compensate with richer needle settings.

The question: how do I make sense of this?

Tomorrow I'm probably just going to put the 50 idle jet back in, back to my original jetting, and hope the original problem is still gone. Any thoughts? Oh yeah, I don't have a number 91 jet, could my bike just be super jet picky?

Re: Hate to do this... but jetting problem

oh yeah, and no airleaks.

Re: Hate to do this... but jetting problem

Maybe your rings are wearing out and your jetting changed? How many miles are on the kit?

Re: Hate to do this... but jetting problem

You might need an idle jet smaller than 45. Try a 42. You need an idle jet that is small enough that you can turn out your mixture screw at least one full turn. You also should never need to have your needle on the leanest setting IMO. Put it at the 2nd leanest setting and then start finding the right idle jet. Leave the 90 main in too. You shouldn't need any bigger than that on a metra.

Re: Hate to do this... but jetting problem

Ok update:

today ran 90 jet, 48, leanest needle. =best performance. Ripping hard. My gut feeling is that I am SLIGHTLY rich on Idle. SLIGHTLY lean for needles. and moderately rich at top.

My Hypothesis. Lowering the idle leaned out the needle range, but not not enough to constitute a raise which would richen it to be unusable. In order to dial it in, I will have to lower the main and/or Idle enough so that I can raise the needle. Either that or I'm gonna have to get a different needle.

Conclusion: I don't have an Idle jet lower than 45, or a main between 85 and 90, or another needle. Looks like I'm staying here for a while. I don't know what the original problem was, but it seems to have passed. Possibly a temporary clog in the main jet. As usual, not completely satisfied, but definately ripping and usable jetting for now.

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