Guest iskone Posted May 31, 2005 Share Posted May 31, 2005 So I got the timing close on Saturday I'd say it was 3-4* retarded as it wouldn't pull above 5,000. I would have set it all the in but I had no more room for adjustment since my dist was hitting the bracket. I didn't realize it wouldn't pull above 5,000 untill I took it on an open road. Around my house it pulled real hard untill 5,000. Heres what happened. I was on the highway and noticed it was starting to back fire all of a sudden at about 4,500. I decided to pull over on the highway to take a look at the motor. When I pulled over the car wanted to die odd because I had no problem idleing for the whole time. I grabbed a screwdriver and turned up the idle, took a look at my dist and cap to see if anything was loose and if the motor was running hot. All was good. So I was going to grab my timing light and check idle RPM when the car just died. As soon as it died POOF my third carb was on fire inside the element area. I blowed on it and tried to smother it with a towel. Anyway after about 1-2 or maybe 3 minutes I got the fire out (turns out I will risk bodily injury to save my car). The damage I'd say is minor 2 elements are toast and 2 fuel lines. Eveything else is untouched even my O-rings behind the base plate are fine. Nothing got into the carbs execpt soot which I already cleaned. I'm planing to put things back together tonight when I pick up my new elements and fuel line. I was thinking about pulling the carb that recived the most damage apart but since the o-rings are fine I would think the rest of the carb is too since the o-rings are the closest to the element (only part on fire) What could have happened? All can come up with was it was back fireing and when the motor died (why I don't know) the flame traveled up the carb because I turned the idle up so high the butterflies were open enough for the flame to travel. I've seen little flames shoot out in the element area before when the timing is off but nothing like Saturday. Any suggestions about how to prevent this from happening during my next attempts at aetting her up? Think I should just go ahead with a carb rebuild? I was thinking I'd look for leaks before I fired it up. I swear to god I can't catch a freaking break with this car!!! I handle a YZF 600 and 30 minutes later all hell breaks loose. At least it is very minor as far as a fire goes, even my paint didn't get touched. ARRRGGGGHHHHHH Isk Quote Link to comment Share on other sites More sharing options...
preith Posted May 31, 2005 Share Posted May 31, 2005 I had similar problems when setting up my Mikuni's. I was trying to run a low float level at 4.5 pst, but it seemed to have the opposite effect and once in a while the bowls would flood. Gas would start running out the venturis and eventually it caught fire, not too bad; got it out right away. Also, the carbs have a tendency to spit gas out, but technically not backfiring. I wonder if this happened enough to the point where the filters where saturated enough and light up? This is one reason why I stayed away from the ITG filter. I was told that eventually the inside would get singed to the point that I'd have to replace it. At $200 a pop, no thanks. EDIT: It sounds like the carb is ok. I'd leave it as is double check the float level, and or replace the float entirely. Maybe try some different size pilot jets? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 31, 2005 Share Posted May 31, 2005 Weird guys. I've never seen flames come out of my carbs and I've only seen gas come out when I'm synching them, and my ITG isn't singed at all 40K miles later. Float level is pretty critical on these carbs. I was flooding around right hand corners when I first got mine on, had to lower the float level to cure that problem. I don't understand what you're doing with your timing Isk, but I can tell you that with your setup you'd have to have the timing VERY VERY retarded to keep the engine from going over 5000 rpm. Retarding the timing like that puts LOTS of heat into the exhaust. Maybe enough that it caught the filter element on fire?!?! Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted May 31, 2005 Share Posted May 31, 2005 Yeah the timing is the culprit I'm sure. I don't know what is going on either. I had the timing set right where it should be but it just wouldn't start so I kept pulling it back till it would, then I advancedd it till it was back where it should be but for some reason when the pointer should have been at 35* it was at zero. So you would think ok the timing is retarded, right. Wrong. When I went to compensate for what seemed like it was retarded timing by resetting where the wheel was in relation to the dist. it would not fire yet alone run, basiclly it was 35* to advanced at 70*. It's very hard to expalin over the net. If I have the same problem today I'll try and take pics of whats going on. And it can't be very very retarded or else it just doesn't run at all. Where do you guys keep the float level. I have no problems arond corners. I should also mention when the car was in nutrual and I stabbed it to about 5000 it wanted to die. It would loose RPM and would die without gas. Carbs? The 5000 rev limit had me thinking about valve float but I figured that can't be these are the same valvetrain as before all that has changed is the rockers. Why would it want to die when it was running fine for a combined 30-40min? Why would it ignite after dieing? Isk Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 31, 2005 Share Posted May 31, 2005 You don't have any Mikuni info? There is a pic of how to set float level in Hot to Modify. You actually have to take the cover off the carb and hold it at a weird angle then take the measurement from the top of the float to the cover. The level should be 12mm from the top of the float to the cover, but it is much easier to understand if you look at the picture. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted May 31, 2005 Share Posted May 31, 2005 I've got How to Modify and the Webber manual but with me so I thought I'd ask first. Man, I hope I get this handled tonight. It has crossed my mind to get a stock replacment dist. I'd prefer a electronic dist. Isk Quote Link to comment Share on other sites More sharing options...
preith Posted May 31, 2005 Share Posted May 31, 2005 You don't have any Mikuni info? There is a pic of how to set float level in Hot to Modify. You actually have to take the cover off the carb and hold it at a weird angle then take the measurement from the top of the float to the cover. The level should be 12mm from the top of the float to the cover, but it is much easier to understand if you look at the picture. The newer Mikuni's are designed so one doesn't have to remove the bowl cover. These have the set screw/10mm nut on the fuel inlet side. Turning it down raises the bowl level. You can pull out one of the emulsion tubes and measure from the cover, but I forget exactly which point. I beleive they cover this in Honsowetz's book, and it was supposed to be 21 or 24mm, can't remember that either. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 31, 2005 Share Posted May 31, 2005 Never noticed that before, but you're right, you can measure from the fuel level to the "horizontal surface at the top of the jet block hole" and it says 21mm according to How to Modify. That's much easier. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted May 31, 2005 Share Posted May 31, 2005 What page is that on? Is there a section about identifiying if I have the newer style you refer to? Isk Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 31, 2005 Share Posted May 31, 2005 Page 112 and there is a picture as well. The externally adjustable style has a 10mm lock nut with a little flathead screw in the middle. Not really clear in the picture. Quote Link to comment Share on other sites More sharing options...
Clifton Posted May 31, 2005 Share Posted May 31, 2005 Running too lean will cause a backfire through the intake. FI or carbed. Quote Link to comment Share on other sites More sharing options...
preith Posted June 1, 2005 Share Posted June 1, 2005 Running too lean will cause a backfire through the intake. FI or carbed. Commonly reffered to as an afterfire. This may sound kinda funny, but it's more like a pop rather than a backfire from the tailpipe. This is a pretty easy way to tune in the pilot jets. Just keep stepping up until the poping goes away, then go one larger yet, and fine tune with the miture screws. Quote Link to comment Share on other sites More sharing options...
Guest iskone Posted June 1, 2005 Share Posted June 1, 2005 Hmmm I've heard the popping sound alot when trying to set my timing. I think I have alot of work ahead. Isk Quote Link to comment Share on other sites More sharing options...
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