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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> 38 mm Mikuni Roundslide help: won't idle /cgi-bin/YaBB.pl?num=1144426139 Message started by vroom1776 on 04/07/06 at 09:08:59 |
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Title: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/07/06 at 09:08:59 Hey gang, So I got one of Lancer's USED 38 mm Mikuni roundslide carbs... Need some help... So I stuffed it in there with the jets he had in there, a 330 main and a 30 pilot. Ran pretty okay from scratch, but it took a bit for it to idle down if I gave it some gas. I fooled around with the pilot till it seemed return to idle correctly. Rode it around some. Seemed fine at low and midrange. Stumbled real bad at WOT. Dropped the main jet to a 320. Fired it up and it ran fine, but didn't have a chance to test WOT. Now I can't get it to idle properly. It just started doing it when I got back from somewhere and the bike was sitting for a couple of hours. Symptoms: Starts fine with choke, idles okay for a little bit with the choke off, then slowly idles down and stalls. If I keep increasing the rpm by turning the idle screw in, the idle speed increases, but then it starts decreasing again. Then fuel starts leaking out of the overflow tubes and I kill the bike. I've tried going dwon to a 27.5 pilot, but it seemed very lean at all PMS screw settings and had the same result. Now I've got the 30 in agian... I keep checking the plug, too. When I first pulled it out when it first started doing it, it was very fouled, but it wasn't a proper plug chop so you can't really tell anything about it. The plug with the 30 in was a little fouled, but when I first started it up the throttle was stuck about half way open as the link under the carb had come out on install... killed the engine and adjusted it, so that doesn't tell me anything either. Any help appreciated. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by lancer on 04/07/06 at 09:30:38 If you have fuel coming out of the overflow tubes then the needle valve in the float bowl is sticking open and letting fuel flow in continuouly. As the fuel comes in and the floats come up the needle valve should close and stop the fuel, until the floats come down far enough and then the needle valve opens again to refill the bowl. Take the bowl off and check the floats (if the floats have fuel in them then they have a hole somewhere...letting them fill with fuel), and check the needle valve for some kind of dirt or something that is keeping it from closing properly. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/07/06 at 09:35:53 Pretty sure the floats are fine and that there is no dirt in the needle valve (fresh can of carb cleaner :)). I will check again, though. The fuel only leaks when I fully seat the idle screw (or get a little close...) Oh yeah, I'm at 4000 feet (1220 meters) above sea level. Maybe I should drop the float a mm or two? Getting good at pulling the carb out, but my hands are all dried out from gasoline! |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by Savage_Rob on 04/07/06 at 13:20:38 vroom1776 wrote:
Nitrile gloves. They look like green surgical gloves and are petroleum resistant. You can get 'em at hardware and auto parts stores. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/07/06 at 18:03:25 Checked. The float needle seems to seat all the way. It is easy to move and there are no scraping type sounds. I also blasted some more carb cleaner in there. The floats float. I filled the float bowl halfway with carb cleaner and they both floated. However, as I type this, I realize that IF there is a leak, it could be at the top... Also, I measured the float height. From the rib that the gasket sits on on the upper portion of the float to the float arm while the carb was up-side-down. The top of the float arm reached 17 mm, as accoding to spec. So, assuming the floats do not leak, what now? Thanks, V |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by lancer on 04/08/06 at 04:12:21 Put 'er back on the bike and try it again. If the needle valve and floats are working properly there should not be any fuel coming back out the vent tubes. If there is still some difficulty then try the float adjustment you mentioned. It would also be good to pray for your carburetor...God is concerned for every detail of out lives. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by Savage_Rob on 04/09/06 at 15:00:48 My 38mm Amal Mk2 may have a similar issue but I'm not sure. When I finish a ride, I can tap the ends of the vent tubes with my finger and get a small amount of gasoline on my fingers. This seems to be less than a drop and I see no evidence of any dripping fuel, though it doesn't mean it may not happen in small amounts. While it doesn't seem normal to me, I haven't tried tracking it down. I've wondered if I might have to adjust the float because of the slight tilt of the bike since the carb isn't quite level. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/09/06 at 17:41:56 my carb is in there pretty level. I cleaned out the float needle pretty well, too, but there may be some sticking. Now, still, once it warms up, it will idle down slowly and stall. Gas doesn't poor out, but there is still some. I have to keep blipping the throttle to keep it from stalling. When I'm moving along at say, 1/4 throttle, when the pilot circuit is dominant, I don't think I get any gas dripping out and it runs great. Top is still a hair rich. I'mm gonna try a 315 main. Rob, how well does your savage idle? |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/10/06 at 08:16:19 If the float needle is stuck open, should it leak gas from the overflow at WOT? |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/10/06 at 15:28:26 Okay, just checked it while I was on a smoke break at work... yeah, a little gas just kinda sitting there at the bottom of the overflow tubes. My float valve must still be stuck open... Grrr >:( I'm tempted to try and remove it and soak it in CC overnight... Seems liek a bad idea... Soak the whole carb... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by lancer on 04/10/06 at 15:55:42 I am calling in an order tomorrow and will put a new float needle valve on the list for you. I really do not like stuff like this to go on when I have sent out a carb to some one. You said that the needle valve moved oK for you, as it did for me when checking it over before sending it to you, but I am wondering if the spring in the valve assembly may be weak and not able to hold it closed when it is supposed to. That is why I am ordering a new one for you, so we can at least eliminate the valve as a possible cause...if not solve the problem once for all. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/10/06 at 16:10:39 Lancer, You're a good man. I'm going to clean it out again tonight. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/10/06 at 19:31:46 So I yanked the carb this evening and came up with a good test for the float. I filled the fuel line with carb cleaner and gently pushed the flaot arms up. It definitely seated. Fuel stopped flowing once the brass pin (the larger of the two moving pins, and not the one with the weird flower or gear like shape) stopped moving up. When I lowered it, carb cleaner came out again. Like I said, I just now tried this. It seemed to close just as well before, but I'm not 100% sure. I'm gonna go home now, reinstall the carb and see if it's any better. Photo: http://bikepics.com/pics/pics/suzuki-savage-97-bikepics-560719.jpg Sorry it's blurry... it was the best lit one... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/11/06 at 07:46:03 Okay, so here's this AM: Temp, about 60 F. Choke on. Hit the starter button... a little life. Choke off. Hit the starter button. Life. Idle. Idle. Idle. Idle. Idle. Idle... Idle... Idle... Idle... Idle... Idle... Idle... Idle... Die. A very,very small amount of gas at the bottom of the overflow tubes. Throttle plus ignition = life. Ride to work (not very far at all :( ). Idled okay for 2 or 3 minutes (then I had to go into work), no gas coming out of overflow tubes, but the spot below there was wet w/ gas. I still have the idle screw pretty much all the way in... maybe 1/2 - 3/4 turns out. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/11/06 at 08:56:15 Just checked. A bit more gas on the ends of the overflow tubes. When I masured the cloat height the otehr day, it was 17 mm, which is the lower end of spec. It seems that it would seat all the way if I put it UP??? to 18 mm... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/12/06 at 08:39:53 Hey, To anyone reading this thread besides Lancer and SR (he read it at least once!): BTW I got a USED carb from Lancer, NOT a NEW one. ...don't want to scare off any one... Lancer: Any suggestions until the new valve comes? Also, I put in the 310 main... still too big... stumbles and cuts out at the top, btu I'm getting more of the top end back as I go to smaller jets. Will install a 300 main today... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by lancer on 04/12/06 at 09:58:52 I kind of stumped right now. Is there any possibility of an air leak around the carb anywhere? The needle, needle jet, main jet, & pilot jet are all new. I believe the gasket on the bowl was new too if I remember right ?? Check the rubber gasket on the carb top. It seemed that it was OK when I looked at it but I could have assumed too much with it. If those things are OK then we are back with the needle valve again. According to the tuning chart the #310 main jet is what is called for at 4000' above sea level. but if you engine wants it leaner then make it leaner. If you need smaller jets than the #300 let me know, I have a #280 & #290 in the box. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/12/06 at 10:05:25 I will test for air leaks at the screw on cap, rubber flange, and air filter. The float bowl gasket seems in good shape/new. I previously checked for an air leak at the rubber flange by spraying carb cleaner at the interface and listening for an rpm increase... nothing. As far as the 310 goes, it may be related to the float problem somehow... just too darn much fuel... don't worry about the jets. I can get them easily and cheaply in town... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by Savage_Rob on 04/12/06 at 14:29:40 Hmmm, I'm gonna need to check mine also. I finally got the vacuum port put back on and it's pretty solid now. Prior to that, she wouldn't run unless I had her on PRI and I prefer the vacuum setup. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/13/06 at 08:16:52 I put mine on prime. Seems to have "fixed" the problem... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by Savage_Rob on 04/13/06 at 10:24:52 I never find any gas dripping or any evidence that it has... just that I can get a very slight amount on my fingertip by tapping the ends of the vent tubes after a ride. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/13/06 at 10:58:26 yep, me too (now). However, if I go outside right now, 4 hours after I got off it, there is gas at the bottom of the tubes... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by Savage_Rob on 04/13/06 at 11:38:40 vroom1776 wrote:
Hopefully you turned the petc0ck off of PRI when you parked. If you left it on PRI, it stands a much greater chance of overflowing just sitting there. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/13/06 at 12:58:37 Yeah, it's on "RUN." But there is still the leak-drip-leak-drip going on... >:( |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by lancer on 04/13/06 at 17:50:40 I get the leak-drip thing as well, but I think it is from the pet c o c k loosing its ability to seal properly, so I just turn it to the off position. I have noticed these last months that even then it still leaks a little...I am looking at replacing the whole thing now. |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by orrin7 on 04/13/06 at 19:16:26 sounds like the petcock is both of you guys problem. but don't buy a new one the guy at the motorcylce shop told me last week , there is a rebuild kit for them |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/19/06 at 09:48:40 From "Carbs": http://suzukisavage.com/cgi-bin/YaBB.pl?board=RubberSideDown;action=display;num=1145100757 Lancer wrote: I just found some interesting info on float level and tuning and will get it posted here shortly. I think it may help your situation. OK, the guideline I found suggests that if the engine is acting like it is too rich at full throttle, then lower the fuel level by 1mm in the bowl. Then test ride to see if you have improvement. End I just want to keep all the info in one place... Allright, so, like I said, above, the float height is presently 17mm, the bottom end of spec. So I need to move it to 16mm, correct? What do I need to bend? The float arm? leave the center tab alone? |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/20/06 at 12:23:48 bump significant changes... |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by Tim Krantz on 04/21/06 at 09:57:13 Just wondering what air filter are you using on the Mikuni..... I was thinking of a sock type, or K&N. If K&N, does it have to have an angular tube-to air cleaner? What about the crancase breather?? |
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Title: Re: 38 mm Mikuni Roundslide help: won't idle Post by vroom1776 on 04/21/06 at 10:16:04 Yep, KN filter. I don't know the aprt # offhand as I got it from lancer. If you want to use a KN pod with the stock carb, it is RU-1250. Breather filter should be available at any HD place. Mine was made by drag specialties. I orginally put it here: http://bikepics.com/pics/pics/suzuki-savage-97-bikepics-428348.jpg but I cut up the air box some more and stuffed it in there. I think some folks are running the straight round KNs, but not real sure how they forced them in there. For me, removing the battery case and mangling the air box was the way to go. |
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