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Author Topic: Idle Mix for Top Speed  (Read 424 times)

Superchuck

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Idle Mix for Top Speed
« on: August 15, 2013, 02:52:56 AM »
Help with idle mix and top speed:

So last night around midnight I moved the needle to the richest notch.  I'm running CV carb with 17.5 pilot, 120 main, big exposed K&N filter, and bazooka with the hot pipe removed.  Just got back from my test rides and this is what I've found:

When setup by the dealer, idle screw setting was way out... didn't measure it, but it was somewhere in the order of 6-8 turns out.  That always ran great with my stock setup.

2-2.5 turns out is my highest idle speed.  I brought it to 3 to be on the rich side.  When I rode it down an exit or two on the highway though, it could barely maintain 55 comfortably (using 1/4 to 1/2 throttle).  1/8 throttle was super quick to respond, but lacked the gusto once it got to 1/4 throttle.  No real power per-say.

Stopped at a gas station, and brought the idle screw to 5 turns out.  Did the same highway test, and this maintained a higher comfortable cruising speed... almost 60 mph at half throttle.  Still not super comfortable there, so I did it again.

At 7 turns out, it can maintain idle once warm (no throttle needed to keep it from dying at stop lights), has a delayed attack when blipping the throttle, but has some serious gusto once it hits.  Also, I can easily maintain 60 mph or slightly more at about half throttle.  Anything higher than that and I get these 'over-revving' sounds that I (maybe falsely) attribute to dryness, leanness, and/or overheating.

It still feels fairly dead when cranking any higher than half throttle at highway RPM's, but what could this mean?  Shim it richer than the richest notch on my needle?  Go to a larger main jet?  Also, is it bad that I have my mixture screw set so much richer than its 'sweet spot' as far as idle is concerned?  I don't mind the 'calm before the storm' delayed response when blipping the throttle if it means I have more power at the useable range.  Plug is a chalky brown... a little lighter than hershey's chocolate, not white.

I'm tempted to try my 122.5 main.  I also have a 125.  From what I've read, the AVL is known for this low end power that I'm getting, and that is great.  Should I try and get more out of the top end, or will everything else suffer?

Comments, questions, pointers, and the like... let me hear it all.  I know nothing about this besides what I've read here and last night I finally popped my 'getting inside a carburetor' cherry.  ;)

tooseevee

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Re: Idle Mix for Top Speed
« Reply #1 on: August 15, 2013, 12:30:42 PM »
Help with idle mix and top speed:

So last night around midnight I moved the needle to the richest notch.  I'm running CV carb with 17.5 pilot, 120 main, big exposed K&N filter, and bazooka with the hot pipe removed.  Just got back from my test rides and this is what I've found:

When setup by the dealer, idle screw setting was way out... didn't measure it, but it was somewhere in the order of 6-8 turns out.  That always ran great with my stock setup.

2-2.5 turns out is my highest idle speed.  I brought it to 3 to be on the rich side.  When I rode it down an exit or two on the highway though, it could barely maintain 55 comfortably (using 1/4 to 1/2 throttle).  1/8 throttle was super quick to respond, but lacked the gusto once it got to 1/4 throttle.  No real power per-say.

Stopped at a gas station, and brought the idle screw to 5 turns out.  Did the same highway test, and this maintained a higher comfortable cruising speed... almost 60 mph at half throttle.  Still not super comfortable there, so I did it again.

At 7 turns out, it can maintain idle once warm (no throttle needed to keep it from dying at stop lights), has a delayed attack when blipping the throttle, but has some serious gusto once it hits.  Also, I can easily maintain 60 mph or slightly more at about half throttle.  Anything higher than that and I get these 'over-revving' sounds that I (maybe falsely) attribute to dryness, leanness, and/or overheating.

It still feels fairly dead when cranking any higher than half throttle at highway RPM's, but what could this mean?  Shim it richer than the richest notch on my needle?  Go to a larger main jet?  Also, is it bad that I have my mixture screw set so much richer than its 'sweet spot' as far as idle is concerned?  I don't mind the 'calm before the storm' delayed response when blipping the throttle if it means I have more power at the useable range.  Plug is a chalky brown... a little lighter than hershey's chocolate, not white.

I'm tempted to try my 122.5 main.  I also have a 125.  From what I've read, the AVL is known for this low end power that I'm getting, and that is great.  Should I try and get more out of the top end, or will everything else suffer?

Comments, questions, pointers, and the like... let me hear it all.  I know nothing about this besides what I've read here and last night I finally popped my 'getting inside a carburetor' cherry.  ;)

            I wish I could help you, but I can't because our situations aren't equal, e.g., my needle still has the hard plastic collar which I believe just covers the highest notch & is lifted 3 shims higher (if I remember correctly) whereas you are using the e-clip grooves in the needle.

          Also I can't help you on anything WOT as I'm still in break-in (800 miles). All I can say is that my engine behaves perfectly around town in 1st, 2nd & 3rd. No bogging at any rpm or flat spots or dieing at stop signs. Out on blue roads it easily gets to 50/55 in 4th & cruises very easily at any 5th gear speed (45/50/55). I don't know it's top in 3rd as I can't slam it yet with only 800 miles.

          I will say this: I think your mixture screw is out way too far. I don't know why it's running that far out (I think mine is a hair over 2 turns out). I hesitate to comment any further because our situations don't seem to be the same for some reason.

          A mixture screw out that far to run right would seem to indicate you need a larger Pilot, but we are running the same 17.5 so
it looks like you might need to experiment with a higher needle height with one shim at a time before jumping to a higher size Pilot?

          I wish some of the Real experts would chime in here. I only know MY engine & MY carburetor & I've learned it all by trial & error & it took a lonnng time.   
2008 RE AVL Classic
1977 Shovelhead Hardtail Bobber

tooseevee

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Re: Idle Mix for Top Speed
« Reply #2 on: August 15, 2013, 01:08:59 PM »

Comments, questions, pointers, and the like... let me hear it all.  I know nothing about this besides what I've read here and last night I finally popped my 'getting inside a carburetor' cherry.  ;)

           Chuck, I forgot to mention before that my engine kick starts cold with two kicks - touch nothing, no throttle no enrichener. So I may be a hair rich which is OK by me. It then runs at a low idle (wants to be blipped a hair) for about a minute then will idle nice left alone. I don't increase it with the idle speed screw because I then have to turn it back down at the first stop sign - why bother?
2008 RE AVL Classic
1977 Shovelhead Hardtail Bobber

Buckeroo

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Re: Idle Mix for Top Speed
« Reply #3 on: August 16, 2013, 12:38:08 AM »
well, I am not a real expert.  The fuel enriching knob is hard to reach without leaning over and hunting for it.  I have learned to live with a fast idle so the bike will run normally at all other speeds.  Set where it is only takes me two kicks at most and usually only one to start it.  It puts real slow when cold and a little too fast when warm, but I can live with it.  I get between 65 and 70 mpg and running it a little rich at idle doesn't seem to bother the AVL at all.  my 2 cents.
This bike was stored for 3.5 years.  It had fallen on its side for awhile. I claimed it about a year and a half ago. Thus the low miles and inexperienced owner.
2008 Bullet Electra Classic 500
Classic Frame and AVL motor
Electric Start
Electronic Ignition
5 speed
CV Carb

High On Octane

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Re: Idle Mix for Top Speed
« Reply #4 on: August 16, 2013, 12:54:30 AM »
I keep my idle kind of low.  Real chunky and lobey when it's cold and then once it warms up it has a nice "pa plop - pa plop - pa plop".  I don't like having a high idle, just burns unnecessary gas at stop lights.  Plus having a chunky idle gets the attention of all the motor heads out there.   ;D

Scottie
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Superchuck

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Re: Idle Mix for Top Speed
« Reply #5 on: August 16, 2013, 01:23:08 AM »
Thanks guys, yes my idle is definitely what I'd call chunky.  Today I actually leaned it up to 5 turns out because it was having trouble idling at anything below 'hot' running temperature.  I really enjoy the growl the richer mixture gives me.  It's not super fast to accelerate from a stop... I think a leaner setting would give me more of that, but like I said in the post above I like the more 'useable' range...  it has more pull at 1/4 throttle with my current mixture than a leaner screw setting would be.  I have to feather the clutch a bit more when starting, which isn't great, and I am considering leaning it out another turn.

I haven't don't true plug chops yet, but I think that's my next step in zeroing this in.  As far as power band goes, it is a bit sluggish from start (not a big deal to me) and really roars through 1/4 and 1/2 throttle.  It does OK at full throttle, but seems proportionately like a letdown compared to how fun 1/4 and 1/2 throttle are.

That being said, I basically live between 1/4 and 1/2 throttle, even on the highway.  I like to go fast, but it just seems like a bad idea to me to be flogging at WOT constantly.  A leaner mixture would give me more immediate acceleration from stop, but at what cost?

We'll try some plug chops and probably a bigger main jet, then go from there.  That being said, how praytell does one 'shim' up the needle?  Do you just put a little washer-like thing beneath the white plastic needle collar?  Like between the needle's collar and the bottom of the slide assembly?  If so, what happens with the little plastic nub that protrudes down from the collar and feeds through a tiny hole in the slide... seems like it'd get in the way, or the needle would lay crooked...?

Thanks again for any input.  Keep it comin cause I really have no idea what I'm doing.  It's fun though, isn't it?   ;)

Buckeroo

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Re: Idle Mix for Top Speed
« Reply #6 on: August 16, 2013, 04:16:00 AM »
This bike definitely keeps one thinking about how to improve it.
This bike was stored for 3.5 years.  It had fallen on its side for awhile. I claimed it about a year and a half ago. Thus the low miles and inexperienced owner.
2008 Bullet Electra Classic 500
Classic Frame and AVL motor
Electric Start
Electronic Ignition
5 speed
CV Carb

tooseevee

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Re: Idle Mix for Top Speed
« Reply #7 on: August 16, 2013, 11:47:22 AM »
We'll try some plug chops and probably a bigger main jet, then go from there.  That being said, how pray tell does one 'shim' up the needle?  Do you just put a little washer-like thing beneath the white plastic needle collar?  Like between the needle's collar and the bottom of the slide assembly?  If so, what happens with the little plastic nub that protrudes down from the collar and feeds through a tiny hole in the slide... seems like it'd get in the way, or the needle would lay crooked...?

Thanks again for any input.  Keep it comin cause I really have no idea what I'm doing.  It's fun though, isn't it?   ;)

            Yes. That's exactly what you do. The little nub? You file it off with a fingernail file no problem. All you do is put the shim under the collar & put it back together.

             Your other choice would be to remove the collar & then you could retune using the needle grooves, an e-clip & shims if necessary. I wish *I* had done that in the very beginning, but now I have what I have & don't want to start over. I am incredibly happy with the way my engine is performing now. I went for a ride yesterday & didn't even care that I was cold after I had left in just a T-shirt.

             You can get the Mikuni shims at a Jap bike dealer or as some said you can find them at good hardware stores. Take the needle with you to the hardware store. You don't need to take the needle to the bike dealer - the parts guy will know what Mikuni needle shims are.

            I still don't think your mixture screw should be cranked out that far, but it's you figuring out your carb, not me.
2008 RE AVL Classic
1977 Shovelhead Hardtail Bobber

tooseevee

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Re: Idle Mix for Top Speed
« Reply #8 on: August 16, 2013, 11:56:48 AM »
well, I am not a real expert.  The fuel enriching knob is hard to reach without leaning over and hunting for it.  I have learned to live with a fast idle so the bike will run normally at all other speeds.  Set where it is only takes me two kicks at most and usually only one to start it.  It puts real slow when cold and a little too fast when warm, but I can live with it.  I get between 65 and 70 mpg and running it a little rich at idle doesn't seem to bother the AVL at all.  my 2 cents.

            Sounds to me like you are talking about the idle speed screw not the enrichener. Increasing the idle with the idle speed screw doesn't change the idle fuel/air mixture.

             Running at a fast idle doesn't effect how the bike runs at RPMS above idle. It just burns more gas at stop signs (among other things, clutch wear, etc.).
2008 RE AVL Classic
1977 Shovelhead Hardtail Bobber

Buckeroo

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Re: Idle Mix for Top Speed
« Reply #9 on: August 16, 2013, 05:53:03 PM »
I just recently found the enricher screw through a thread here.  I hunted around for it and decided that there was only one screw.  Still, I have had no problems with the CV carb.  I still have been getting 65-70 mpg set like it is.  I'll mess with it some if needed, but so far it doesn't bother me.
            Sounds to me like you are talking about the idle speed screw not the enrichener. Increasing the idle with the idle speed screw doesn't change the idle fuel/air mixture.

             Running at a fast idle doesn't effect how the bike runs at RPMS above idle. It just burns more gas at stop signs (among other things, clutch wear, etc.).
This bike was stored for 3.5 years.  It had fallen on its side for awhile. I claimed it about a year and a half ago. Thus the low miles and inexperienced owner.
2008 Bullet Electra Classic 500
Classic Frame and AVL motor
Electric Start
Electronic Ignition
5 speed
CV Carb

tooseevee

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Re: Idle Mix for Top Speed
« Reply #10 on: August 16, 2013, 09:14:54 PM »
I just recently found the enricher screw through a thread here.  I hunted around for it and decided that there was only one screw.  Still, I have had no problems with the CV carb.  I still have been getting 65-70 mpg set like it is.  I'll mess with it some if needed, but so far it doesn't bother me.

        That's perfectly fine. It's just that there are some of us out here who have never been happy with what the federal government or some factory tells us we want in a motorcycle. We know what we want & it's not a strangled & choked engine that is just barely allowed to run & has all kinds of stuff hung onto it that isn't necessary & that blows its own oil all over its air filter & muffler & that the reasons for are mostly bullshit.

          Simple, bulletproof, pragmatic, easily fixed on the side of the road. That's what I want. I'd even rather have points, but so far so good. I can replace the points on the harley (which I built) at a NAPA store & set my timing with a matchbook cover & easily obtained tools if I'm not carrying which I would be if going any distance. I've never taken any kind of bike to a dealer to work on it.   

         I just won't have all kinds of hoses & tubes & cans, & bells & whistles running all over the place & I want to turn the lights on when I want them on. I moved the horn, too  ;)]     

          Your bike is perfectly fine left alone. I just like you riding one because the goal is to outlaw us; most states are Very anti-motorcycle & bow to anti-bike lobbyists & clueless blue-haired old ladies (of both sexes). If you work on it yourself or support small independent shops, all the better.
« Last Edit: August 16, 2013, 09:19:17 PM by tooseevee »
2008 RE AVL Classic
1977 Shovelhead Hardtail Bobber

Buckeroo

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Re: Idle Mix for Top Speed
« Reply #11 on: August 19, 2013, 09:37:23 PM »
I'm not big on all the hoses, catalytic hot pipes, PAV, etc.  I'm not a good mechanic.  But I can work on stuff and eliminate things if I know that I'm not going to damage something else in the process.  Adjusting carbs and ignition systems has been my Achilles heel.  My friends used to say that I could build a beautiful motor, but I couldn't make it run.  So, I limit my skills to what I know.
This bike was stored for 3.5 years.  It had fallen on its side for awhile. I claimed it about a year and a half ago. Thus the low miles and inexperienced owner.
2008 Bullet Electra Classic 500
Classic Frame and AVL motor
Electric Start
Electronic Ignition
5 speed
CV Carb

Superchuck

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Re: Idle Mix for Top Speed
« Reply #12 on: August 21, 2013, 03:32:20 AM »
I think both of those posts deserve an, 'Amen.'  So, Amen, Gentlemen! 

After checking the plug from last ride, it's charred and black.  Cakey even.  Definitely running rich, but I imagine that was due to my massively enrichened mixture screw.

Today after work I put the 122.5 main jet in and a fresh sparky and took it for a spin.  Shot up I-95 for a few exits, and did a plug chop on the side of the interstate at full throttle.  I was amazed at how the enfield pulled, even at half throttle.  I was able to maintain 65 mph no problem, and I was able to get up ABOVE 70 mph.  It felt like it could've hit 80 but I didn't want to break something (or myself).

At the full throttle plug chop, the brand new spark plug I put in was chalky and white.  Shockingly, I'm still running lean at full throttle.  I got gas at an exit, then shot back down the interstate for about 5 miles at half throttle.  This maintained about 60-62 mph no problem.  I did another plug chop at half throttle (but with the same plug that I just used for full throttle).  It was chalky and white again even at half throttle.  I don't know enough about plug chops to tell how accurate this reading was.  I read somewhere that you should always do plug chops with a fresh plug, but I figured I ran it for enough miles at that half throttle setting that it would've darkened up if my half-throttle setting was significantly richer than WOT.  Someone please enlighten me to the significance of fresh sparkies in richness testing...

Pulled back in to home and leaned up the idle screw 2 full turns (now currently at 3 turns out if I remember correctly).  The idle wasn't seeming strong, even after wailing it at WOT on the highway.  I then swapped out the 122.5 main jet for my 125, which is the largest I have.  I'm hoping I'm not still lean at WOT with this jet, but only time will tell.  I'll get on it again tomorrow and try it on for size.  My long awaited EMGO Reverse Cone Shorty Silencer has finally shipped too, so I'll soon be swapping the bazooka for it.  I imagine that will lean things out a little bit more, eventhough I've already removed the hot-pipe.

If this jet doesn't richen up my mid-throttle I think the next step is to shim up the needle a bit.  I'll have to use some washers since the one cycle shop I called doesn't have mikuni shims.  They said they have some could possible may work, but told me to bring in the carb to make sure.  Sounds too much like hard work, so I'm gonna stick to the hardware store a block from my house.  But first, the 125 main jet.

Chuck

tooseevee

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Re: Idle Mix for Top Speed
« Reply #13 on: August 21, 2013, 12:37:59 PM »
I think both of those posts deserve an, 'Amen.'  So, Amen, Gentlemen! 

After checking the plug from last ride, it's charred and black.  Cakey even.  Definitely running rich, but I imagine that was due to my massively enrichened mixture screw.

Today after work I put the 122.5 main jet in and a fresh sparky and took it for a spin.  Shot up I-95 for a few exits, and did a plug chop on the side of the interstate at full throttle.  I was amazed at how the enfield pulled, even at half throttle.  I was able to maintain 65 mph no problem, and I was able to get up ABOVE 70 mph.  It felt like it could've hit 80 but I didn't want to break something (or myself).

At the full throttle plug chop, the brand new spark plug I put in was chalky and white.  Shockingly, I'm still running lean at full throttle.  I got gas at an exit, then shot back down the interstate for about 5 miles at half throttle.  This maintained about 60-62 mph no problem.  I did another plug chop at half throttle (but with the same plug that I just used for full throttle).  It was chalky and white again even at half throttle.  I don't know enough about plug chops to tell how accurate this reading was.  I read somewhere that you should always do plug chops with a fresh plug, but I figured I ran it for enough miles at that half throttle setting that it would've darkened up if my half-throttle setting was significantly richer than WOT.  Someone please enlighten me to the significance of fresh sparkies in richness testing...

Pulled back in to home and leaned up the idle screw 2 full turns (now currently at 3 turns out if I remember correctly).  The idle wasn't seeming strong, even after wailing it at WOT on the highway.  I then swapped out the 122.5 main jet for my 125, which is the largest I have.  I'm hoping I'm not still lean at WOT with this jet, but only time will tell.  I'll get on it again tomorrow and try it on for size.  My long awaited EMGO Reverse Cone Shorty Silencer has finally shipped too, so I'll soon be swapping the bazooka for it.  I imagine that will lean things out a little bit more, eventhough I've already removed the hot-pipe.

If this jet doesn't richen up my mid-throttle I think the next step is to shim up the needle a bit.  I'll have to use some washers since the one cycle shop I called doesn't have mikuni shims.  They said they have some could possible may work, but told me to bring in the carb to make sure.  Sounds too much like hard work, so I'm gonna stick to the hardware store a block from my house.  But first, the 125 main jet.

Chuck

            This is just a feeling I have from rereading this whole thread again starting early this morning (I have no life  :) ).

             I wish you had tried raising your Needle Jet one shim before you changed from the 120 to the 122.5 Main Jet just to see what happened. I think you might have found that this brought your Mixture Screw back in line (2 - 2 1/2 turns out) + it might have also brought your WOT to what you're looking for. Maybe I'm wrong, but I think raising the needle has an effect on WOT the same as increasing the Main Jet size does. Ace & the other real experts will correct me, I hope.

           And you don't need to take the whole carb off & with you to get shims; just the needle. A really good hardware store should have tiny washers that will be perfect.

            I think you may find your plug is always black with the mixture screw out that far unless all your riding is at highway speeds.

            PS: To refresh my settings - Wide open exhaust & intake, 117.5 Pilot, 110 Main, 3 shims under the needle collar, 2 turns out on mixture.
I can't do the Main yet, not enough miles.   
2008 RE AVL Classic
1977 Shovelhead Hardtail Bobber