anthc24 Posted October 8, 2014 Report Share Posted October 8, 2014 Hi, new here, got myself a trails bike last year to ride over the winter as I race mx, basically when I out it away after the winter it wasn't running, iv just got it back out to fix ready for the winter and it started after a few kicks with no petrol in and I think the petrol was even turned off! It cut out and couldn't get it going again even when I put petrol in. When I put petrol in it came p***ing out of one of the pipes going down towards the back shock, guessing this is an overflow? I stripped the carb down and there was green stuff in the bottom of the float bowl and on the jet, green hard stuff. Cleaned everything up and still won't fire. Any help is much appreciated Regards Quote Link to comment Share on other sites More sharing options...
huski Posted October 8, 2014 Report Share Posted October 8, 2014 Does it spark? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted October 8, 2014 Report Share Posted October 8, 2014 The green crap is the additives that replaced lead, benzine etc in petrol It can be very very difficult to shift fully from all the jets and small passages in the carb. You probably have not got it all out. Have you stripped the cold start enrichment mechanism, jet and passage? It once took me several days with various solvents, petrol system cleaner, fine copper wire and compressed air to clean some road bike carbs that had this stuff in. Even ultrasonic cleaning does not always clean the small passages. Once you get it going again put some fuel injection system cleaner in to remove the final residues or your bike may run weak and pink or overheat. The best thing to do when parking a bike up for more than a couple of months is to drain the carbs and fill them with thin oil Quote Link to comment Share on other sites More sharing options...
anthc24 Posted October 8, 2014 Author Report Share Posted October 8, 2014 Does it spark? The green crap is the additives that replaced lead, benzine etc in petrol It can be very very difficult to shift fully from all the jets and small passages in the carb. You probably have not got it all out. Have you stripped the cold start enrichment mechanism, jet and passage? It once took me several days with various solvents, petrol system cleaner, fine copper wire and compressed air to clean some road bike carbs that had this stuff in. Even ultrasonic cleaning does not always clean the small passages. Once you get it going again put some fuel injection system cleaner in to remove the final residues or your bike may run weak and pink or overheat. The best thing to do when parking a bike up for more than a couple of months is to drain the carbs and fill them with thin oil Thank very much for the quick replys, this was the first time I have ever stripped a carb so only Done what I was capable of doing. I think the best thing I could do is just take it the the local trails shop and see if they can fix it. But it must be sparking if it started today? How is that even possible after it wouldn't start for months and has been left standing for months? Almost a year! Could it have something to do with the float bowl that the petrol is coming from the overflow pipe? Quote Link to comment Share on other sites More sharing options...
goudrons Posted October 9, 2014 Report Share Posted October 9, 2014 If it's been stood a while, as already mentioned green furry crap seems to leech out of modern petrol and gum everything in the carb up. The advice about draining the float chamber when left unused is wise, just shut the fuel tap off when you're finished with the bke and slacken the cap at the bottom (27) until it stops dribbling. By the sounds of it, the inlet valve to the float chamber has jammed open, allowing fuel to poor in from the tank unrestricted. As you've discovered, it pours out of the float chamber overflow and vent tube, but it'll almost certainly pour out of the float chamber and into the engine due to the fact the carb on these are tilted so far forward when mounted. This will fill the crankcases with raw fuel, flooding it up. First, as prompted already, clean the carb out well, if unsure about how it goes back together, there are plenty of Mikuni diagrams floating around the 'net like this http://www.allensperformance.co.uk/exp-vm.html Pay attention to the float chambers inlet valve and seat (34) and jets, particularly the narrow pilot jet (21) Remove them and look through the small hole to verify they are clear, often you've no choice but to poke them with a fine strand of copper wire to clear them. The green crap is stubbon, but don't be tempted to chisel at it. The carb's float height is very important on these due to the mounting angle, as a high shut off height will allow the chamber to pour over allow the engine to flood up, too low and it pinks and bangs as it's starved of fuel. Search the forum/internet, there's plenty of advice about setting them correctly. Now that's sorted, remove the spark plug, lay the bike flat on the right hand side and repeatedly pump at the kick starter, I'll bet it fires black sooty petrol out of the plug hole. Keep at it until this black petrol starts to clear up. Refit the carb and plug and try starting again. Quote Link to comment Share on other sites More sharing options...
anthc24 Posted October 10, 2014 Author Report Share Posted October 10, 2014 If it's been stood a while, as already mentioned green furry crap seems to leech out of modern petrol and gum everything in the carb up. The advice about draining the float chamber when left unused is wise, just shut the fuel tap off when you're finished with the bke and slacken the cap at the bottom (27) until it stops dribbling. By the sounds of it, the inlet valve to the float chamber has jammed open, allowing fuel to poor in from the tank unrestricted. As you've discovered, it pours out of the float chamber overflow and vent tube, but it'll almost certainly pour out of the float chamber and into the engine due to the fact the carb on these are tilted so far forward when mounted. This will fill the crankcases with raw fuel, flooding it up. First, as prompted already, clean the carb out well, if unsure about how it goes back together, there are plenty of Mikuni diagrams floating around the 'net like this http://www.allensperformance.co.uk/exp-vm.html Pay attention to the float chambers inlet valve and seat (34) and jets, particularly the narrow pilot jet (21) Remove them and look through the small hole to verify they are clear, often you've no choice but to poke them with a fine strand of copper wire to clear them. The green crap is stubbon, but don't be tempted to chisel at it. The carb's float height is very important on these due to the mounting angle, as a high shut off height will allow the chamber to pour over allow the engine to flood up, too low and it pinks and bangs as it's starved of fuel. Search the forum/internet, there's plenty of advice about setting them correctly. Now that's sorted, remove the spark plug, lay the bike flat on the right hand side and repeatedly pump at the kick starter, I'll bet it fires black sooty petrol out of the plug hole. Keep at it until this black petrol starts to clear up. Refit the carb and plug and try starting again. Thank you so much, very helpful! This is also exactly what the local tails shop mechanic said! Taking the carb up to him tomorro for a proper clean out etc, I'm confident enough stripping and re-assembling but not really sure on checking the float height etc. Does anyone know what the idle and air screw should be set at or can someone link me to an owners manual so I can see how much oil etc to use when I service it. Regards Quote Link to comment Share on other sites More sharing options...
goudrons Posted October 11, 2014 Report Share Posted October 11, 2014 (edited) Unfortunately, this forum will not let me link to a guide on float height, but there's a good guide in the first link here. https://www.google.co.uk/?gws_rd=ssl#q=beta+rev+3+float+height Manual here, but it's for an '08, so this model has a different carb and master cylinders, think they were all paper books before this, so try Ebay for one of the exact year, oil capacities are the same though. http://www.betamotor.com/system/attachments/0000/0749/REV3_inglese.pdf The air mixture screw setting is around 1 and 1/2 turns to 1 and 3/4 turns out (as a guide). Adjusting it back and forth from this and you should start sensing the motor hit a "sweet spot" and idle smoothly, make sure you're warmed it up first. Too rich and the motor will sound dull, heavy and laboured (applying the choke a little will make it a lot worse) Too weak and the motor will struggle to return to an even idle after a blip of the throttle. It'll "winga ding ding" on the over run rather than settle quickly to a smooth idle (applying the choke to richen it a little will make it better) Idle speed is personal choice and can be set when warmed up and you're out riding. Too slow and it'll stall to easy particularly if the clutch drags a little (very common), too fast and it'll drive it's self with the clutch out and in gear. Edited October 11, 2014 by goudrons Quote Link to comment Share on other sites More sharing options...
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