Dragonslayer Posted October 18, 2012 #1 Posted October 18, 2012 Finished up the 87 last Friday and got her back on the road. She seemed to be running fine but I didn't get a chance to put some miles on her until Tuesday. So, Tuesday I rode up to Dahlonega to visir RandyR and do a carb sync. On the ride up she was running great, with great acceration and no sign of the 4200rpm stumble that she had been having. But, she is still sucking gas at 28MPG (1up averageing 70mph on interstate). :doh:When we hooked the carb tune up #3 was pegging and the others were fairly close. We did the carb sync and I headed back towing my trailer. The ride back got about the same mileage (1up towing trailer averging about 60MPH and about 30 miles of stop start in traffic) I had really hoped that finding and correcting the loose main jet tube on #4 and new main jet tube orings on all four would have corrected the MPG problem but it didn't. I did notice some black soot at the exhaust tips. I'm now thinking one or more weak or faulty coils. I'm about to go out and pull the plugs to read the fuel burn conditions. I'll post pictures of the results as soon as I do. All help and suggestions are greatly appreciated.
Dragonslayer Posted October 19, 2012 Author #2 Posted October 19, 2012 Here is what I found when I pulled the plugs [ATTACH]72330[/ATTACH] #1 was 100% black soot [ATTACH]72331[/ATTACH] #2 was 50% black soot [ATTACH]72332[/ATTACH] #3 was 25% black soot [ATTACH]72333[/ATTACH] #4 was 25% black soot Evidently all of the cylinders are running rich 1 & 2 more than 3 & 4. What are some things to check and do to get them to burn more lean?
frankd Posted October 19, 2012 #3 Posted October 19, 2012 Bob, The dark plugs say all 4 cylinders are running rich.....Most Venture plugs come out almost white. Have you checked the float levels? Frank D.
Flyinfool Posted October 19, 2012 #4 Posted October 19, 2012 And the obvious. Did you remember to take off the choke? Ever check the diaphragms?
mbrood Posted October 21, 2012 #5 Posted October 21, 2012 The few Ventures I have worked on were all showing quite rich on the plugs... the needle shim was my first attack... seemed to cure it on two. That black means money (fuel) and performance wasted.
djh3 Posted October 21, 2012 #6 Posted October 21, 2012 Hotter plugs maybe? But still you say the MPG is no where close to what should be so I would think too much fuel is getting in somewhere.
DragonRider Posted October 21, 2012 #7 Posted October 21, 2012 Get another bike in running condition that you dont have to keep rebuilding, repainting, rejetting, resyncing, etc, etc, etc, too much time spent tinkering and not enough time riding.............:rotfl::rotfl:
Dragonslayer Posted October 22, 2012 Author #8 Posted October 22, 2012 Bob, The dark plugs say all 4 cylinders are running rich.....Most Venture plugs come out almost white. Have you checked the float levels? Frank D.I have in the past but not lately, I'll check it out.
Dragonslayer Posted October 22, 2012 Author #9 Posted October 22, 2012 And the obvious. Did you remember to take off the choke? Ever check the diaphragms? The choke is off and i double checked the cable adjustment. I just had checked and repaired a few pin holes on the diaphrams.
Dragonslayer Posted October 22, 2012 Author #10 Posted October 22, 2012 (edited) Hotter plugs maybe? But still you say the MPG is no where close to what should be so I would think too much fuel is getting in somewhere.The plugs that are in it are new NGK recommended plugs for the motor. This leads me to the question: Is it possible that coils and/or spark plug wires could be delivering a weak spark to the spark plugs causing poor fuel ignition. If so what is the best way to verify hot spark current at the spark plug cap? Edited October 22, 2012 by Dragonslayer
Dragonslayer Posted October 22, 2012 Author #11 Posted October 22, 2012 Get another bike in running condition that you dont have to keep rebuilding, repainting, rejetting, resyncing, etc, etc, etc, too much time spent tinkering and not enough time riding.............:rotfl::rotfl:Yea I know, however being unemployed at the moment buying a new bike right now is not on the immediate horizon. I'm a little jealous at the new trike in your garage. But, according to what I've been reading. You've been doing a little tinkering as well. I quess I'll just have to keep tinkering on the Dragonslayer bike and pretend it's what I really love doing. Kinda hate having to return the problem free 2nd gen I've been riding as a loaner.
frankd Posted October 22, 2012 #12 Posted October 22, 2012 This leads me to the question: Is it possible that coils and/or spark plug wires could be delivering a weak spark to the spark plugs causing poor fuel ignition. If so what is the best way to verify hot spark current at the spark plug cap? Pull the spark plug cap, and plug in a known good spark plug. Make sure the base is grounded. Then start the bike and look at the spark. If it's strong and blue things are fine. Frank D.
justfun1 Posted October 23, 2012 #13 Posted October 23, 2012 Not knowing the full history here but in case you have not done it yet, I'd check the main needle settings to be sure it is 2 1/2 - 3 turns out from bottoming out. That was the issue with my 89, it seems to run well at 2 3/4 turns out.
Dragonslayer Posted October 23, 2012 Author #14 Posted October 23, 2012 Not knowing the full history here but in case you have not done it yet, I'd check the main needle settings to be sure it is 2 1/2 - 3 turns out from bottoming out. That was the issue with my 89, it seems to run well at 2 3/4 turns out.I'm unsure which setting your talking about. do you mean the screw setting at the bottom of the diaphram cover plate?
jdog910 Posted October 25, 2012 #16 Posted October 25, 2012 if you have never adjusted them you have to drill out the cover
Dragonslayer Posted October 26, 2012 Author #17 Posted October 26, 2012 if you have never adjusted them you have to drill out the cover OK so your talking about the jets recessed inside the hole at the bottom of the diaphragm plate that you have to be careful with to avoid damaging the seat. The post above suggest 2 1/2 to 3 turns out or 2 3/4. I have also heard 1 1/2 to 2 turns out. Who knows the correct distance out from bottom? I have set these correctly years ago and have not touched them since.
justfun1 Posted October 31, 2012 #18 Posted October 31, 2012 Sorry it took so long to answer, it's been a while since I have had time to get on here. Yes I was talking about the jets under the carbs. On both my '86 and '89 IZ have thjem set at between 2 1/2 & 3 turns out. Mike
frankd Posted October 31, 2012 #19 Posted October 31, 2012 I don't think you can just set them 2.5 turns out and guarantee the idle mixture is correct. I mean, if they ALL adjusted properly at a fixed point, why would they give the carbs adjustable jets?...they'd just put a fixed idle jet in. The further out you have the screws, the richer the idle mixture is. How I do it is to adjust them all for maximum idle speed, and then turn them inward (clockwise) until the engine just slows down a little. You can see this on the tach if you look closely. You may have to adjust the idle speed screw to keep the idle speed correct. In fact, the mixture will be easier to adjust if you slow it down to about 750RPM temporarily. Then I do it a 2nd time, adjusting each for about 25 rpm drop from peak. Then adjust the idle speed back to 1000 RPM. This way, the engine will idle smoothly, and you will be slightly on the lean side, and it should give you better gas mileage. Now this will not take you from 28MPG to 40, but it may take you up a couple MPG. Auto mechanics used to refer to this procedure as the 'lean drop method'. I do know that a rich idle mixture will give you dark plugs and reduce your mileage by 3-4 MPG. When my 1200 was relatively new, my gas mileage to and from work went from abut 42 MPG down into the 30s. My dealer told me to drive it to the shop door, and he came out with the hose from their Exhaust Gas Analyzer. He stuck it into the tailpipes and said it was rich. I'd never touched the idle adjustment. He set up an appointment for my carbs to be adjusted. They removed the plugs that are in the exhaust pipes just down from the top, and used their EGA to adjust each cylinder idle mixtures for the proper amount of CO. They synced the carbs and took my money. My gas mileage went back into the low 40s and my spark plugs lightened up. Before they service, all of my spark plugs were dark, so all 4 cylinders were rich. Most of my to work trip was expressway driving. Because these bikes take so little throttle opening to run 65MPH, the idle mixture is quite important.
Kirby Posted October 31, 2012 #20 Posted October 31, 2012 Bob, I know you've probably already done this but I gotta ask. Are you sure you don't have some kinda obstruction in your air intake? Dirty Filters? Rat bed? Bird nest? Just trying to help.
icebrrg3rd Posted October 31, 2012 #21 Posted October 31, 2012 Hey Frank, how do you know when the screws are turned out all the way to the maximum idle speed prior to turning them back in? Do you turn one at a time or turn all out and then go back in? And does messing with the screws mess up the sync? Or just the idle speed? Sorry Bob for hi-jacking... -Andrew
frankd Posted October 31, 2012 #22 Posted October 31, 2012 No, it won't change the synchronization. What you are doing is adjusting the amount of gasoline in the idle mixture, not the air. To adjust the mixture screws, turn the screw in, until it bottoms out (be gentle), and then turn it out until the engine speed peaks. You can hear it OR you can watch the tach. If you have a 2nd Gen and no tach, you could hook up one of your carb. sync. gauges to any cylinder. The faster the engine turns over (at idle) the higher the vacuum reading will be. After you get the first cylinder peaked, turn the idle mixture screw in until the engine slows down slightly. This will put you on the lean side of the perfect mixture. Then do the same for the next cylinders, and then the other two. After the first pass through, I do it a 2nd time, except this time I don't bottom out the screws again, I just turn them CCW to the peak and then I lean out the mixture (turn CW) until I see about a 25 rpm drop from peak speed.
Dragonslayer Posted November 1, 2012 Author #23 Posted November 1, 2012 Bob, I know you've probably already done this but I gotta ask. Are you sure you don't have some kinda obstruction in your air intake? Dirty Filters? Rat bed? Bird nest? Just trying to help. No bird or rat nest. the filter doesn't look that dirty but, I'm gonna make sure it isn't a factor.
k9cottage Posted November 1, 2012 #24 Posted November 1, 2012 i use a colourtune plug to do the mixture setting best thing i ever got when i had a kawasaki Z1300 with 6 mixture screws works well on the 99 rsv you can do all carbs in the time it takes to change the plugs with engine at idle just turn the mixture screw untill the colour turns to a bunson blue. [ame=http://www.youtube.com/watch?v=6hFUvQ4gaPc]Gunson Color Tune Plug Color - YouTube[/ame]
k9cottage Posted November 1, 2012 #25 Posted November 1, 2012 [ame=http://www.youtube.com/watch?v=xEZ0-uN0NA4]Tuning MGB with Gunson colortune from Accuspark - YouTube[/ame]
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