da lipper Posted March 26, 2013 Report Share Posted March 26, 2013 I've been looking through the posts but can't see anyone with the same problemes i'm having. Was out on the bike on Sunday and it started to bog down and not rev untill it eventually cut out and wouldn't start again. (luckily i was only about 50 yds from the garage! Thought it was dirt in the carb so i took it off had a look, couldn't see anything in the bowl, put it back on, started the bike on choke and it ran for about 30 secs then the revs started to rise and it cut out and wouldn't start again. I then took the carb off the bike and stripped it completely, sprayed carb cleaner everywhere and assembled it all together again, put it back on the bike and checked the slide was in the correct place, wasn't stuck open, the throttle cable wasn't getting snagged anywhere and started it again. It did the same thing again, started after the fourth kick, just the usual slightly higher than idle revs on choke, ran for about 40 secs then the revs started to rise and then it just bogged down and cut out. i never once touched the throttle. The air filter is nice and clean as i did it a couple of weeks ago, it has a new spark plug (even tried the old one back in) but only seems to start if the carb has been emptied of fuel. I'm at a complete loss here. HELP! Quote Link to comment Share on other sites More sharing options...
coop650 Posted March 26, 2013 Report Share Posted March 26, 2013 What does the plug look and smell like when you pull it after it stalls? I am not very familiar with these gas gas engines yet, but I suggest you check the crankcase oil level, also look on the stator side for oil behind the flywheel. I say this because it sure sounds like a possible crank seal leak. Quote Link to comment Share on other sites More sharing options...
jandyb Posted March 26, 2013 Report Share Posted March 26, 2013 Could be the fuel tap getting clogged too... Disconnect the fuel hose, and check if the fuel runs freely. -Jan Quote Link to comment Share on other sites More sharing options...
lineaway Posted March 26, 2013 Report Share Posted March 26, 2013 Is it fresh fuel? I would replace just to make sure! Quote Link to comment Share on other sites More sharing options...
sting32 Posted March 26, 2013 Report Share Posted March 26, 2013 (edited) It sounds to me like a Fuel issue for sure. several things to check. ..Is the tank vent working? I've seen people pinch vent hoses under the tank. ....is petcock (shut off valve) working and flowing freely? .._..Delorto has a fuel filter where the line meets the carb, very fine mesh, hopefully you cleaned it, but worth a second check of course, might be getting crap from tank . .......it is possible you have still overlooked a jet or another AIR or FUEL passageway. WIll it run right with choke on, or not right but better? Tips... Everyone says, Do not use wire to clean jets, I read all the time people making jets bigger with steel type wire by scraping the holes bigger in them, still right now that is not your problem... IMHO if you do push something out something is blocking the low to mid fuel circuit. +++The rule about cleaning the carb honestly is, clean it, if it runs your done, if it doesn't run, you clean it again, if it runs your done, if it don't, clean again. IF the carb is absolutely good, then you have to start hunting for leaks in the intake system, which is leaning the FUE/AIR mixture after the carb. 2 places known to hapen is the rubber boot from carb to crank case. if the bike will run on choke, this can be diagnosed with a short shot of ether around the intake boot. The crankcase seal behind the flywheel (which you have to split the cases to change) can leak, sometimes you can prove this by blocking the vent hose. Or you can carefully shot a little ether there too. Careful, I dont want you to burn your eyebrows off, make sure you have good ventalation, stand back, all that... Add a fuel filter to tank line Edited March 26, 2013 by sting32 Quote Link to comment Share on other sites More sharing options...
b40rt Posted March 26, 2013 Report Share Posted March 26, 2013 Are you getting a spark when its not starting ? Quote Link to comment Share on other sites More sharing options...
jse Posted March 26, 2013 Report Share Posted March 26, 2013 Are you getting a spark when its not starting ? I'd also check for a sheared flywheel key, common in older bikes. Jon Quote Link to comment Share on other sites More sharing options...
sting32 Posted March 26, 2013 Report Share Posted March 26, 2013 (edited) OP seems to be showing classic signs of stuck float needle, maybe fuel source issues to the bowl at least? and since he only took off bowl to "look in the bowl" (not really much you can see if there isnt a bunch of obvious "crap" in there...) plus if there was crap, it is stuck in the jets... I bet, the floats probably moving but needle is still closed or mostly closed because of gunk, causing not enough gas into carb, until it sits long enough to fill the bowl... THat is IMHO of course. Key on flywheel I guess I hadn't give that much thought, since the 2 times that I have seen that happen, the bike wont ever start (sheered that key and moved too far to spark anywhere near when it needed to. But yes, I see that could happen and barely be off, maybe, but really wierd that it wouldn't just keep running though badly, where as it sounds by description that it is starved for fuel, then dies... Just my 2nd 2 bits worth. Hope he figures it out and lets us all know, Fighting issues like this, can drive you bat skat crazy, don't ask me how I know that, lol. One more thing, I had a spring loaded needle, they used them back when I got my 04 pro,. Well the needle wore itself apart. you see the needle is built in 2 pieces with a spring, built in a way that the needle is exactly same lenght when not compressing the spring, as a solid needle... But mine must have vibrated enough that it was growing longer (because of spring and no stopper anymore to keep it a certain length... This was causing normal and even empty of fuel float level to close the gas off entering the carb. Ok what I am about to tell you is maybe TMI, but to me it was so weird I even posted a self drawn picture to what happened, on this very forum, lol. So what happened to me was, I was on 3rd loop of 2 day trials (day 1) and my bike started 'lean' and poping down the trail, the next section I couldn't ride it was as if I'd shut gas off and forgot to turn on when I entered the section. So off to camp to figure this out, cab off, bowl off, blow through everything, trying to not disturb float of course. Then it happened, on the 4th assembly, test and remove the pin holding the floats in place, fell out, floats fell out, and the little damn needle fell onto the pan I was working in the grass on, but in 3 pieces (spring, a tiny plunger, rest of needle). that is when I found the issue, but how to fix, nobody had a needle. I ended putting it back together and I could kind of feel where it tried to stop from doubling the lenght... so with 2 more hands, we just crimped hard on the needle to the little plunger, making it solid, rode the last loop and the whole next day without problem. got new needle in mail the following friday. I still have that needle in tool box it was sooooooo frustrating. it is a little traveling trophy so to speak. Edited March 26, 2013 by sting32 Quote Link to comment Share on other sites More sharing options...
coop650 Posted March 26, 2013 Report Share Posted March 26, 2013 OP seems to be showing classic signs of stuck float needle, maybe fuel source issues to the bowl at least? and since he only took off bowl to "look in the bowl" (not really much you can see if there isnt a bunch of obvious "crap" in there...) plus if there was crap, it is stuck in the jets... I bet, the floats probably moving but needle is still closed or mostly closed because of gunk, causing not enough gas into carb, until it sits long enough to fill the bowl... THat is IMHO of course. He does say he took the carb completely apart but I tend to agree with you. I mentioned the crank seal because the description fit the diagnosis but it very well could be carb related. I used to be a mechanic I am just not overly familiar with these Gas Gas engines yet. Quote Link to comment Share on other sites More sharing options...
da lipper Posted March 27, 2013 Author Report Share Posted March 27, 2013 Thanks for the replies guys. So i took the carb off again and noticed that the fuel shut off valve was sometimes sticking. I'm not sure how it comes apart so i ended up bending the metal part that the floats push up on, so that i could get the valve completely cleaned, which did have a few little bits of grit in it. I thought that the little spring was too compressed so "stretched" it a little, assembled the the carb and tried to start the bike again. Nothing. Took the carb off again and the bowl was bone dry. I had stretched the spring too far and no fuel was getting into the carb! So, took the carb off again and removed the spring, back onto the bike and she fired into life! I ran around for a little while to get the engine nice and hot and went to adjust the idle and she cut out, and the next thing i saw was fuel pouring out from the carb ! So i'm guessing the carb really needs the spring, especially at the correct length! Can you purchase the fuel shut off valve or do you need to buy a whole new carb? And what is the correct way to remove the valve. Besides the carb overflowing the bike was running really good at lower revs, very responsive on the throttle but wouldn't clear at higher revs, but i'm guessing this was because of too much fuel in the carb as it couldn't shut off. Quote Link to comment Share on other sites More sharing options...
bmseven Posted March 27, 2013 Report Share Posted March 27, 2013 http://www.trialscentral.com/forums/topic/2942-float-height/page__hl__%2Bfloat+%2Bheight Quote Link to comment Share on other sites More sharing options...
thats_a_five Posted March 28, 2013 Report Share Posted March 28, 2013 Yes, you can buy the needle and seat. You do not have to buy the whole carb. The seat unscrews from the carb body. While you have things apart and ordering parts, check your floats. There have been reports of the floats absorbing fuel and sinking. This will cause fuel to flow contulously into the carb, flooding the engine. If they are fuel saturated, replace them. Be sure to set your float height correctly as described in the link posted above by BMSeven. Quote Link to comment Share on other sites More sharing options...
sting32 Posted March 29, 2013 Report Share Posted March 29, 2013 the image on the right is how the arm should look without floats, and NO you dont compress the spring. In fact because of my problem in the past, i would replace needle with new style without spring, but that is just me. Quote Link to comment Share on other sites More sharing options...
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