 Kenny & the Jets...
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Well, my 07 SM is currently set up with the BC ABEK & long TORS, & no internal mods.
When I bought the bike earler this year I was time-challenged so I let the dealer do the install & tuning. They set it up with 145 mains, 42 pilots, stock needles & 2 shims, screws 2.5 turns out. With that setup by my butt dyno it was clearly rich down low, & lean on top, but with no decel popping anywhere. Bottom line is it wasn't right, & from my perspective far from optimal. It still ran well, but I knew it could do better with proper tuning.
It is now running 155 mains, 42 pilots, stock needles with no shims, & screws less than 1 turn out. It feels pretty good everywhere by my butt dyno. With the current setup it is probably a touch rich at idle. The mains are probably within 1 size of optimal. Mid range is responsive & it pulls strong.
I have the Kawi CV slide springs on order & those will go in once I'm otherwise satisfied that the jets & air screws are as good as they are going to get.
When my butt dyno is satisfied then it will go to a real dyno for confirmation, & at that I'm most interested in the A/F readings.
Given the above info, what do you think of trying 40 pilot jets & backing out the air screws?
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Re: Kenny & the Jets...
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What colour are your plugs? If you spend most of the time cruising at lower speeds and they are white, you are too lean. Most of the gang is using 42 or 45 pilots with turns on the idle screw between 2 and 3.5. With the air box removed and TORS you are moving a lot more air through your engine. You probably need some shims under your needles or TBS ones. Less than 1 turn out on the idle screws??? Something doesn't add up.  Check your plugs.
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Re: Kenny & the Jets...
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I recently got rid of the stock air box and installed the K&N's.Played with the jetting again.I had the #140 mains and the #45 pilots or so I thought.I pulled out the pilot jets and I had already had the #42 pilots installed.That's what I get for not writing things down.I re-installed the #42 pilots with #145 mains.Started it up and resit the idle mixture.I too am at less than one turn out.I am running the short TORs on mine.I also have the front restrictor reamed out.Runs good.Thought about going back to #40 pilot jets or maybe even going with some better flowing mufflers.My bike also has hardley any decel popping.I already have the stock #40 pilot jets so I may try them again because that's cheaper than new mufflers,but I have been tempted to get different mufflers.Fuel mileage has also improved,but I have been running slower since they installed this $%^&* stinkin photo-radar everywhere.
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Re: Kenny & the Jets...
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Only 1 turn on the mixture tends to tell me you are lean in the pilot circuit. I run a 48 pilot and can't remember how many turns out I am anymore. As a guess I would think the pilot screws could be turned out another turn or 2 and with TORs might want a slightly smaller main. Best way to tell is to put it on a real dyno then you will know at what throttle position you need adjustment and about how much. Don't forget that the jets over lap so if a big change is needed to either the pilot or main then a small one may be needed to the other. Do a real adjustment to the pilots so they are right and see what happens. I would guess you should go with about a 150 main with the TORs and pods. Where I live I would go 150 main and a 45 pilot and go from there.
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Re: Kenny & the Jets...
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If anything the bike is rich at idle, so I don't know what would be gained by going to larger pilots, given that it's less than 1 turn out now.
There's also no hesitation, & the midrange is strong, so what would a shim accomplish?
Perhaps the point is that not all bikes respond the same way.
It's atypical go smaller on the pilots, but that's what the situation appears to suggest.
Perhaps I should lean the screws more, give it a try, & assuming that everything else is good read the plugs at idle & if that is OK then be happy. But 158's & 40's are daring me to give them a try...
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Re: Kenny & the Jets...
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If everything is as close as you say, I would suggest checking the idle F/A before reducing the pilots. It doesn't matter whether the screw is one turn out or four, as long as the idle mixture is correct.
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With 152 mains & 1 shim the plug insulaters were white to very light tan & with a brief period at idle (seconds) the outer metal ring would accumulate soot. No, I didn't do a WOT plug chop, but that isn't necessary when one puts it all together.
With 155 mains & no shim the idle is better (smooth @ 1000 RPM), but still seems a touch rich. I'll lean the screws some more & see what happens with the plugs.
If I don't need the 40 pilots that's fine with me.
Last edited by B02S4; 11/17/2008 10:38 AM.
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Re: Kenny & the Jets...
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Quote:
Only 1 turn on the mixture tends to tell me you are lean in the pilot circuit. ...
If this wasn't my own bike & I wasn't personally in those carbs I would think the same.
Last edited by B02S4; 11/17/2008 10:42 AM.
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Re: Kenny & the Jets...
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Quote:
With 155 mains & no shim the idle is better (smooth @ 1000 RPM)
Neither of those items should affect idle. The mains should not be contributing when the throttle is closed. Something else changed. Like Dog said, you need to dyno it to make improvements at this point.
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Re: Kenny & the Jets...
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I'm not sure I understand the "something else changed" comment.
The idle improved as a consequence of removing the shim.
In my experience the choice of main effects everything under it to a limited extent, regardless of what the Jenks or similar charts say. That's been my experience with every CV carb I've tuned. From my perspective that is why the most effective tuners get the mains right first & move on from there.
That said, the main jet impact at idle & low speed is of course minimal to nothing, but all other things equal adding or removing shims will directly impact the idle mixture as a consequence of a higher or lower starting needle position.
Last edited by B02S4; 11/17/2008 1:31 PM.
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Re: Kenny & the Jets...
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"Neither of those items should affect idle."
That's correct (also).
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Re: Kenny & the Jets...
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Quote:
...
That's correct (also).
If the needle were removed would it impact the idle?
Given the info provided so far, what do you suggest?
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Re: Kenny & the Jets...
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Quote:
Quote:
...
That's correct (also).
If the needle were removed would it impact the idle?
Given the info provided so far, what do you suggest?
uhhh, you do mean shim? If you remove the needles, the bike will idle but stallout as soon as you give it any gas, or if you forget to put just one of the needles back in, same thing.
I don't know how I know this, I just do, really. 
A word to the wise is not necessary. It is the stupid ones who need the advice.
Pat
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Re: Kenny & the Jets...
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Quote:
the plug insulaters were white to very light tan & with a brief period at idle (seconds) the outer metal ring would accumulate soot.
White plugs means too lean.
Quote:
With 155 mains & no shim the idle is better (smooth @ 1000 RPM), but still seems a touch rich.
What do you mean, seems rich? How can you tell? Is there black smoke coming out the pipes when you accel? Is the engine chugging?
The only real indicator I see are the white plugs...
What about your float height. Could it be set too high? Is your choke circuit partially on? Just seems really weird to me!
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Re: Kenny & the Jets...
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Quote:
...White plugs means too lean...What do you mean, seems rich? How can you tell?...What about your float height. Could it be set too high?... Is your choke circuit partially on?...Just seems really weird to me!
Plugs...yes they looked lean overall, hence the switch from 152's to 155's. I need to take another look at the plugs & reassess.
Float heights...on or about 17 mm, right on spec.
Rich at idle...it's not far off, but there is an occasional "bang" off-throttle on decel (not decel popping), & the bike will run happily off-choke sooner than what I would otherwise expect, & it will soot the plugs if allowed to idle long enough. No baseline RPM dip on rev on return to idle, though. No A/F #'s, so I cant specifically quantify it yet. The easy answer is "go to the dyno & find out", however I'm not ready for that yet. All that said, it's not far off, though.
Choke...is off.
Weird...yes!
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Re: Kenny & the Jets...
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Quote:
...uhhh, you do mean shim?...
No, I meant needle. If the other poster is correct then removing the needle has no effect whatsoever on idle mixture. Is that correct? After all, whether the needle is shimmed or removed is just a matter of detail if the needle has no effect on idle mixture, all other things equal.
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Re: Kenny & the Jets...
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Quote:
Plugs...yes they looked lean overall, hence the switch from 152's to 155's. I need to take another look at the plugs & reassess.
Regarding the white plugs, that's why I asked how you drive the bike. If you cruise around all day in the first 1/3 throttle position, and your plugs are white, your pilot circuit and/or idle circuit is too lean. The mains aren't really in the picture at this setting. Running at full throttle then checking plugs will help determine if the mains are right.
Another check for the right main size is to get up to highway speeds then holding WOT for a few seconds, then back off slightly. If the speed increases, then you are too lean. The opposite is true.
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I appreciate you sharing that info, however I'm already aware of it.
For the purposes of my current carb tuning I run it primarily in the upper powerband. Like I said, I didn't do any WOT plug chops but for my purposes right now I don't need to.
The WOT to 7/8's roll-off did not increase RPMs with the 155's.
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Re: Kenny & the Jets...
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OK Ken,
Seems like you have the bases covered. Good luck and keep us posted.
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Re: Kenny & the Jets...
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Quote:
If the other poster is correct then removing the needle has no effect whatsoever on idle mixture. Is that correct? After all, whether the needle is shimmed or removed is just a matter of detail if the needle has no effect on idle mixture, all other things equal.
What I actually said is that the mains circuit should have no effect on idle. I can only guess what happens when you modify the factory circuits by removing essential parts. Maybe removing the needle altogether allows a small amount of fuel to dribble out of the jet, even when there's no airflow. Let's try to keep this in perspective, eh? The main circuit is not your problem - assuming there actually is a problem. It sounds rather like your carbs might be very close. Incidentally, lots of high-perf motors soot the plugs during extended idle. You know, I really dislike the plug-color voodoo that seems so popular in these forums. It's an urban myth that's absolutely useless on machines like these. In more than 40 years of working with hi-perf motors (only as a hobby, thank gawd), I've yet to meet even one street driver/rider/builder who could tune a motor correctly by examining the plugs. The quarter milers and other WOT racers get it right sometimes, but the rest of us don't ride that way. If you're concerned that there's more to gain at this point, and/or you're disappointed with the performance of the motor, do the dyno. Nothing else will tell you what you want to know.
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Re: Kenny & the Jets...
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I'll have to disagree with Jack again on this plug point. Granted the plug condition is not a sole determination of what you need to do. BUT, it is ONE indicator of what might be wrong. The more input you have in any problem solving situation the better.
There's no urban myth to the fact that if your plugs are black - you're running too rich.
Bob
2005 America, 904cc - sold. 2014 Trophy SE.
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Re: Kenny & the Jets...
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Quote:
What I actually said is that the mains circuit should have no effect on idle.
Jack, I don't disagree with you regarding the mains at idle, however what you wrote (in part) was "Neither of those items should affect idle...", & the only other item that I attributed a slight improvement at idle, all other things equal, was loss of the shim. I actually went up a size on the main, lost the shim, & the idle improved with no other changes.
FWIW my reply wasn't directed solely to you. My "what happens if the needles are removed" question regarding idle mixture was only to illustrate a point with an extreme example that one can either accept or reject on its own merits.
The dyno is the easy way out, however it is not the only way. This is entertaining to me... 
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Re: Kenny & the Jets...
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Quote:
There's no urban myth to the fact that if your plugs are black - you're running too rich.
If the mixture is that rich, you won't have to pull the plugs to know it. I challenge anyone who's tuned a street motor this way to produce a good-looking dyno run. It is an urban myth.
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Re: Kenny & the Jets...
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Quote:
I actually went up a size on the main, lost the shim, & the idle improved with no other changes.
Well, let's think about that for a minute. Let's say for the sake of argument that the mains are contributing to the idle F/A. Wouldn't increasing the jet and removing the shim tend to cancel each other? I really think something else changed that caused your idle to respond differently. If the tuning is really close, you'll detect differences even due to humidity and barometric pressure. My bike always runs leaner (slight midrange flat spot) when the temperature falls below 50F or so, even after the motor fully warm. I'm not sure if this is the result of increased air density or reduced atomization (fuel condensation), but it's consistent. If my bike was setup leaner or richer, the effect would probably be masked.
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Re: Kenny & the Jets...
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From my perspective the only contribution to the slightly improved (less rich) idle in my situation was from the removal of the shim. I posted that earlier. At least one other person argued that should not matter at idle. I reported the changes I made, & you can decide what's causal.
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Re: Kenny & the Jets...
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Got the springs, & they appear to be both lighter & shorter than stock. Once I get into the carbs again I'll measure them side by side.
The 158 mains are on order & I hope to have them by Saturday, USPS willing. I'll stay with the 42 pilots for now. This Saturday is reserved for football - I'll be cheering on my alma mater in college football's most-played rivalry.
The weather isn't supposed to be optimal this weekend in my area (cold), but if the jets get here on Saturday, & I get some time on Sunday, another test is in order.
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Re: Kenny & the Jets...
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Keep us posted on your results. It might turn out that those springs are just the ticket to breathe new life into the carbs.
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Re: Kenny & the Jets...
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I just installed the Kwaker 92081-1760 springs, no test ride yet. The Kawi springs measured 91mm long with approx. 5 turns per inch. The stock springs measured 103mm with approx. 3.5 turns per inch. Both springs are approx. 14 mm OD. The wire gauge appears similar. My "good" caliper's battery was dead, & the cheapo plastic caliper isn't precise enough to measure the thickness; to the naked eye (at least mine) they appear very similar, if not the same.
On my last test run the bike pulled strongly with the 158 mains, no shims, & stock springs, however the plugs were on the lean side of optimum afterward, so I'm going to try 160 mains next.
I want to run the bike with the new springs first & no other changes though, time & weather permitting. More to follow as available.
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Re: Kenny & the Jets...
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I got a brief test ride with the new springs today...it was cold & damp, with temps mid to high 20's F. The bike revs quicker in neutral with the new springs & everything else equal, but I really couldn't tell that it made a difference on the road. There was, however, a very slight but consistent hesitation upon acceleration from cruise that did not exist with the stock springs. It impressed me as being a slight transient lean condition. The hesitation didn't show up just blipping the throttle in neutral.
All other things equal, I'm thinking that maybe a shim will cure that, & maybe slightly richer pilot screws. If that doesn't handle it, then I'll probably go back to the stock springs.
To recap, right now it has 158 mains, no shims, 42 pilots, screws about 3/4 out, & Kwaker springs.
I also have the 160 mains ready to go in. I prefer to make one change at a time, but maybe I'll roll the dice & do the mains & shims together.
Any suggestions (besides a dyno...)?
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Re: Kenny & the Jets...
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I wouldn't point the finger at the springs just yet. Those are really cold temps your testing in, and it's possible that part throttle is running leaner than usual as a result. Do you have enough adjustment left to be able to back out the idle screws a turn or so?
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Yes, the pilot screws are only 3/4 out now...
My best guess is 1 shim & another half-turn or so out will do it.
I'll try the 160 mains & pilot screws first.
More to follow when my schedule & the weather are more agreeable.
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Re: Kenny & the Jets...
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I don't know, pretty much everyone I have talked to and myself included on 2 bikes found the 160 main to be too big.I think if you are only 3/4 of a turn out your pilot may be too big.
Jack I wish I had my dyno print out still, I tuned my bike with the looking at the plugs method and my main setting was dead on right around 13, my pilot needed to be increased and thus my main decreased and now I'm right where I should be. I agree the dyno is the best way but it isn't the only way. I also agree that you can only get so close reading plugs then need a dyno to dial it in perfect or an A/F gauge you can read while riding but I think that would be difficult to get a good idea that way since it isn't as controlled and you need to watch the road.
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Re: Kenny & the Jets...
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I tested the 160 mains today (conditions dry, temp about 41F). Test setup was 160 mains, 42 pilots, no shims, stock needle, pilot screws 1.25 turns out, & Kawi slide springs.
There was a slight but noticable hesitation under mild acceleration from cruise with a cold motor. That situation improved when the motor "fully" warmed up. To me that indicates a mild lean condition in that situation.
The bike pulled stronger on top to redline than it did with the prior 158 setup. So far the 160's seem good.
Now I need to focus on the midrange & low-speed. I think another quarter turn out on the pilots might be closer to the mark. I'll try that next.
Maybe a single "thin" shim on the needles if the above doesn't improve initial acceleration from cruise.
There's no doubt in my mind that that Kawi springs impacted the low speed tuning on my bike. That said, however, as is it will cruise smoothly at any RPM & hold a steady 2 - 3k whereever I set it, in any of the lower gears, and will cruise smoothly on the highway at 4 - 5k.
It's almost there. A couple more minor adjustments & then I'm going to side-gap the plugs & head for the dyno, time & weather permitting.
Stay tuned!
Last edited by B02S4; 12/14/2008 6:45 PM.
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Re: Kenny & the Jets...
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I know when I was dynoing my bike I noticed no performance difference with the 160 vs. the 155 main but on the dyno I was pretty rich. I don't remember the numbers anymore and down low I was way lean with the stock pilot. I was so lean with stock pilot that it didn't even register on the graph on the dyno. I had 160s in then. I now run 155 main and 48 pilot. I have stock springs and needles with no shims.
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Re: Kenny & the Jets...
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Quote:
The bike pulled stronger on top to redline than it did with the prior 158 setup. So far the 160's seem good.
I'm sorry, but I don't believe anyone can feel a one step jet change. That aside, everything you've said and done so far continues to convince me that the problem is the idle circuit. In fact, there's every chance you'll be better with the smaller mains, once the idle is dialed in. It'll take a dyno run to know. You also need to consider that if the temporary lean condition is due solely to the softer springs, eliminating it might burden the idle circuit with a job it wasn't designed to do. It may not be possible to eliminate the mid-throttle hesitation without over-richening the idle and/or mains.
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Hey Dog, you, like I, agree that many a world record were set, many a high output motor got tuned, and TODAY, MANY competition engines get tuned WITHOUT a dyno everytime! Guess there were NO powerfull engines prior to dynos!  Smokey, don't turn over in your grave. Don't get me wrong, they used them, and they are a most valuable tool, BUT LIFE CAN GO ON WITHOUT ONE! 
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J. Prine
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Joined: Feb 2008
Posts: 2,671 Likes: 15 |
I had the bike on the dyno today... No doubt, the Kawi springs induced a transient lean condition just off idle...you could clearly see it on the a/f...that said, they improved throttle response overall. On the whole, the benefits outweigh the lean spike. As it turns out what works best with the Kawi springs in my bike are 152.5 mains, 42 pilots, stock needles with 2 shims, & pilot screws 2 turns out... On the road (dry with temps around 40F) the bike feels good with that setup & I don't feel the relative lean spike at 2300 RPM with that setup. The a/f ratio flutters mostly from 12.8 to 13.2 between idle & 4250 RPM (with 2 lean spikes to 14.2 @ 2300 & 13.9 @ 4000); then clusters about 13.2 to 13.4 from 4250 RPM to 6400 RPM, & then down to about 12.6 to 12.8 to redline. The 160, 158, & 155 mains were more than needed for this combo. So much for the butt dyno... 
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Re: Kenny & the Jets...
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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OP
Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Ahh, one more thing. What I thought were 160's turned out to be a 160 in the right carb and a 152.5 in the left. The parts guy sold me "two 160's".
I closely checked the numbers on the first jet & then installed it in the right carb. I didn't closely check the number on the other jet. Guess what, when we pulled it between dyno runs, & it was a 152.5. Doh!
Moral - always check each & every jet marking individually. Trust, but verify.
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Re: Kenny & the Jets...
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Joined: Jul 2008
Posts: 1,440
Learned Hand
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Learned Hand
Joined: Jul 2008
Posts: 1,440 |
Quote:
What I thought were 160's turned out to be a 160 in the right carb and a 152.5 in the left. The parts guy sold me "two 160's".
OUCH! Man, I'd have a loud conversation with that dude! Glad you're gettin' everything ironed out though. This whole issue of the softer springs reminds me of the days when folks used to "upgrade" their Quadrajets and Hollys by overriding the vacuum linkage at the secondaries. The only thing that most of them ever accomplished was a huge off-the-line bog. The situation with our carbs isn't quite so bad, but I don't think I could live with a tip-in flat spot. Given the lack of an accelerator pump, your results seem to make a case for different carbs.
'08 America Blue/White; Custom Headlamps, Custom Lowers, Clearview 20", Bafflectomy
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Re: Kenny & the Jets...
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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OP
Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Quote:
...OUCH! Man, I'd have a loud conversation with that dude!...
Yeah, that was my first thought also. The parts guy is the chief wrench/dyno operator's son, so I gave him some slack. He made a mistake in providing the wrong jet, but so did I by not closely checking the numbers on both before installing them. But that's what can happen at 0100 in an unheated garage... 
The ironic thing is with the Kawi springs the 152's that I previously installed would have been fine.
I was surprised that it took 2 shims, given my setup, but it did.
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