|
SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Air Fuel Mixture Screw /cgi-bin/YaBB.pl?num=1650240837 Message started by MiamiBobbed on 04/17/22 at 17:13:57 |
|
Title: Air Fuel Mixture Screw Post by MiamiBobbed on 04/17/22 at 17:13:57 Well after a month of having everything that could prevent the old abandoned girl from starting/running – clutch switch bypass, starter relay, complete carb rebuild, spark plug, (cheap) coil, new battery, exhaust leak (thanks to Dave for the header hookup!), etc., I got her running and driving. Serowbot’s carb tuning for beginners helped tremendously! But I have a question: she will ONLY run (with any sized jets installed) with the air fuel mixture screw all the way IN - and in tight. Half to a full turn out and she dies…even at a higher idle speed. That can’t be normal, is it? I am suspecting the cheap Ebay carb rebuild kit did not have the proper sized mixture screw (it also came with a size 200 main jet and unmarked pilot jet!) and I may need a stock replacement. For reference I have a pod filter and an open header. I currently have the carb jetted to 157.5/57.5 but have only had her out 2 times and it backfires quite a bit. I get that I may have to play with the carb jetting more but the fuel mixture screw has me stumped. |
|
Title: Re: Air Fuel Mixture Screw Post by Dave on 04/17/22 at 18:04:22 The jets sound way too big......the adjustment screw is a "fine tuning" adjustment and some of the fuel from the pilot jet bypasses the screw. Your jet is so big that the amount of fuel bypassing the screw is more than the engine needs to idle properly. I start my jetting with a #50 Pilot and #150 main. Since you are close to sea level maybe a #52.5 pilot.....but never a #57.5! You will also never be able to get the bike to run properly with an open header.....and it will backfire and bang and pop continuously until you get a muffler on it. And the muffler should not be one that is just a perforated tube that you can see straight through.....it should have some form of baffle. |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 04/17/22 at 18:09:58 Got it Dave. I am definitely at sea level here in Miami. So, if the jets are too big the air-fuel screw is useless? I do not have a 150 main but I do have a 152.5 (I, of course, can get the 150 to try it as well) and I do have a 52.5 pilot as well as a 55. I have swapped them around so may times now I can re-jet in about 5 minutes! Thanks for the help! |
|
Title: Re: Air Fuel Mixture Screw Post by Dave on 04/17/22 at 18:55:57 The screw controls only a portion of the fuel that passes through the pilot jet. IF the jet is too big then closing off the fuel screw may not help. To choose a proper pilot jet size you get the engine fully warmed up, then drop the idle speed down to around 800 rpm while holding the bike upright so as to keep the bike level so you don't starve the right side rocker for oil at the low idle speed. Then turn the idle fuel screw until you get the smoothest idle. If you can turn the screw all the way in and the engine doesn't start to sputter and run uneven....the pilot jet is too big. If you need to turn the fuel mixture screw out more than 2.5 turns the pilot jet is too small (opening the screw more than 3 turns does not increase the mixture any more). The idle fuel screw has very little affect on any speed over idle, and the pilot jet has very little affect after 1/4 throttle opening. Remember to turn your idle speed back to 1,100 rpm after the adjustement of the fuel screw. |
|
Title: Re: Air Fuel Mixture Screw Post by DragBikeMike on 04/18/22 at 09:59:29 "I am suspecting the cheap Ebay carb rebuild kit did not have the proper sized mixture screw" Greetings MiamiBobbed. Check out this post on carb kits. If you have a mixture screw that looks like the one shown in the post, you need to ditch all the parts that came in your kit and start over. The post explains why. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1641171298 Good luck. |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 04/18/22 at 12:34:44 Mike - I don't know what to say between the pit in my stomach, the feeling of sheer stupidity and wanting to scream/choke somebody (all on me). I guess first THANK YOU. Thanks, for the incredible post from January. You did not have to create it to help knuckleheads like me, but you did anyway. Thanks for sharing that knowledge. Thanks for having a sense of responsibility to help us knuckleheads even though we will just be on to the next poorly thought-out mistake before crying out for help! Thanks for taking the time to make sure our experience with these bikes and on this board is as valuable as possible. Of course, you can probably already tell that my mixture screw looks exactly like the one in your Jan post. All the other parts do to! It’s been a struggle but I actually DID make the old girl run with those parts in my carb. Not well mind you and she was not happy but run she did! I saved all the parts that came out and they are soaking now to go back in with the extra added bits, like a factory gasket. The upside is that I have had my carb off the bike and apart so many times that I can do it in a matter of minutes! I think I’m gonna go puke on my way to do just that. Thanks again for keeping us on the right track! |
|
Title: Re: Air Fuel Mixture Screw Post by DragBikeMike on 04/20/22 at 03:40:04 Thanks for the kind words MiamiB. I'm glad you found the info useful. Now's your chance to pay it forward. I suspect you bought your bogus carb kit on Amazon or eBay. Your purchase history should have details on the kit and who sold it to you. Would be great if you could post that info so we all know more about the kit and the vendor. Good luck with your carb. |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 04/20/22 at 05:06:30 DBM I have a feeling the carb will finally do what I have been reading here that it SHOULD be doing! I purchsed the kit March 22nd on Amazon without doing much homework and assuming it would be fine as a first time bike "mechanic". I would agree 100% with you that it should be steered clear of and my 3 weeks of trying to get the bike to run, with really none of the carb guide adjustments working the way they were laid out, are a testament to that! Its called - Aramox Carburetor Repair Kit, Suzuki Savage 650 86-09 15Pc Carburetor Repair Kit. This is the link: https://www.amazon.com/dp/B07QXZ11VM |
|
Title: Re: Air Fuel Mixture Screw Post by Gary_in_NJ on 04/20/22 at 05:16:33 Bogus carb kits can come from even reputable sources. I purchased a kit for my CB900 this winter from "the best source" according to the forum wisdom for the DOHC CB's. When I got the bike back on the road I was getting 21 mpg (vs 40), the throttle transition from the pilot to the jet was abrupt, and there was a general sluggishness with roll-ons. Turns out the kit had the incorrect needle. It wasn't even close. The OEM style needles are NLA, so my original needles went back in. Problem solved. When available I ONLY buy OEM parts. Buy once, cry once. |
|
Title: Re: Air Fuel Mixture Screw Post by ohiomoto on 04/20/22 at 18:12:28 I agree with the OEM parts comment. From the carb manufacturer or Suzuki. Also, I'm blown away with how focused people are on the air screw. It has such a minimal effect on performance. |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/02/22 at 16:41:31 Well guys, I have my carb back together with either meticulously cleaned original parts or new OEM parts ONLY...no more cheapie parts! She idles MUCH better and the new air-fuel misture screw actually does make the idle go higher or lower! I do have a question though: The bike STILL idles much better (only the slightest surging while cold) with the air fuel screw all the way IN with the 150 main jet and 52.5 pilot jet installed. Additionally, when I rev the engine (sitting in neutral in idle) it dies when I let off the throttle. In other words - rev/die/start, rev/die/start, etc. I am assuming I need to change a jet? Thanks again for the support here! |
|
Title: Re: Air Fuel Mixture Screw Post by LANCER on 05/02/22 at 18:28:53 If your screw is all the way IN and your engine is still running you need a smaller pilot jet...assuming the adjustment of the screw was done properly with the engine completely warmed up. (ie. riding several miles before adjusting) |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/02/22 at 18:56:20 Understood Lancer and thanks! I'll give it another run tomorrow just to make sure. I am new to the motorcycle mechnic world but with the high flow exhuast (muffler tip directly on the header) and only a pod air filter (air box removed) I really hoped the 52.5 pilot the bike came with when I bought it might work! Stock pilot is 47.5 (145 main) correct? If so I'll be buying more jets! |
|
Title: Re: Air Fuel Mixture Screw Post by zipidachimp on 05/03/22 at 00:33:24 My sea level bike runs great with 52.5/152.5 and white spacer reduced to 1/2 thickness, pod filter. 150 main also ok. Cheers! 8-) |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/05/22 at 18:00:35 Got the 150 and 50 jets in and installed. Same issue - rev it, it dies. Start it, rev a little, it dies. Not sure whats going on but I'll sleep on it and keep plugging away. Where does everybody get their OEM jets? Thanks again for all the advice. |
|
Title: Re: Air Fuel Mixture Screw Post by ohiomoto on 05/05/22 at 18:14:13 Wait a minute...you have a not running issue?!! I thought we were talking about jetting. I must have missed that, didn't read the OP, or simply got off-topic. 47545F544558520302310 wrote:
Did you check the fuel petcock? |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/05/22 at 18:51:48 Fuel petcock is a brand new raptor, a real one. Battery is new and charged. Coil is new. Spark plug is a new iridium. Air box has been removed and a pod filter has been installed. Carb has been cleaned, both scrubbed physically and sonically. Carb has also been completely rebuilt (more than once) now with all OEM parts. White spacer has been removed and setup with 2 washers. I have a shorty muffler directly on the header. Tank is clean and gas is fresh. She starts fine and idles nice and smooth but when I rev a bit on the throttle she dies when I let off. #52.5 pilot jet did it, #50 pilot jet is doing it too. I don't have a #47.5 to try that. I feel like I am missing something but I don't yet have the experience to pin point it. Altho, if I'm honest I have felt very close to having her running great for about a month now! ;D |
|
Title: Re: Air Fuel Mixture Screw Post by justin_o_guy2 on 05/05/22 at 19:46:12 Have you experienced success with the New petcock that you Certainly removed the plastic cover from? |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/05/22 at 20:34:34 Hmm...I'm gonna go with a yes? I have ridden the bike before all the cheap carb parts came out and OEM parts went in. It rode very rough and backfired ALOT but she ran. I assume if I had NOT removed the plastic cover from the petcok it would not be rideable at all? |
|
Title: Re: Air Fuel Mixture Screw Post by Gary_in_NJ on 05/06/22 at 03:48:35 When you installed the Raptor, did you cap the vacuum nipple? A bike that won’t come off idle is usually a result of the jetting being too lean. You may be chasing the wrong problem. I suggest the use of an UNLIT propane torch too seek a vacuum leak. |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/06/22 at 05:39:11 Vacuum was capped when raptor was installed but I can run down a leak too. Thanks Gary! |
|
Title: Re: Air Fuel Mixture Screw Post by ohiomoto on 05/06/22 at 17:06:01 Okay. Sorry that I missed all of that but this isn't a jetting topic. Obviously, there is some fuel delivery or (not as likely) electrical problem. This is way beyond the air screw of jetting. What you describe sounds like classic vacuum petcock issues. But you have that covered. One thing that gets overlooked a lot on here is the diaphragm and slide. I had a worn and sticky slide and it caused a few head-scratching lean conditions. If that side doesn't open, the bike is will exhibit some of the extreme lean symptoms you decribe. |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/06/22 at 17:22:12 Ohio I have been thinking along those lines as well. When carb was rebuilt the diaphragm and slide seemed to be good. (no holes or wear visible in diaphragm - slide in decent condition...I cleaned them up a bit...but WTH do I know!) However, they are 11 years old and the bike DID sit outside abandoned for 3-4 years. The rubber is a little tacky and well, the slide...if I blow in the narrow strip above the air intake it does go up and down. No idea if that means its "good" but it aint completely stuck. Anyway, I guess what I am trying to say is that even tho every screw, jet, spring and adjuster was replaced on this carb the slide and diaphragm were not (and at about $170 I now remember why!) |
|
Title: Re: Air Fuel Mixture Screw Post by ohiomoto on 05/06/22 at 18:27:06 You can pull the air filter and observer/fiddle with the slide. Not sure that's it. Also, POD filters sometimes block the back of the cab. |
|
Title: Re: Air Fuel Mixture Screw Post by MiamiBobbed on 05/06/22 at 18:29:30 Hmm...block the back of the carb...you have me thinking now. Will check that out too! Thanks Ohio! |
|
Title: Re: Air Fuel Mixture Screw Post by Gary_in_NJ on 05/07/22 at 08:32:38 To test the diaphragm, reach into the back of the carb and raise the slide. When you let go it should not fall with gravity, but have a dampened movement. You should also hear air movement as it drops. If it hangs before dropping or slows down and speeds back up, there is a problem If it simply drops with no air sounds, there is a problem. When you check for a vacuum leak, be sure to check the throttle shaft area too. |
|
SuzukiSavage.com » Powered by YaBB 2.2! YaBB © 2000-2007. All Rights Reserved. |