sawtooth Posted June 22, 2013 Report Share Posted June 22, 2013 (edited) Just got an '07 Rev3 250cc and have noticed the revs are taking way to long to drop when I let the throttle off making it really noisy and pretty unpleasant to ride :-( The bike sounds very much like a 2-stroke motocross bike being ramped around?! (not good) I have another thread with some general questions about the bike but i think this problem needs looking at in depth. Someone mentioned either crank seals (allowing air in) or idle set too high, i've turned the idle right down and still have the issue so is it likely to be crank seals? If so, whats the score on changing those, any guides around? While we're at it, I don't have a handbook and can't find one to download anywhere for the 2007 so in this pic below the red arrow is the idle yes? So what is the green one and what should it be set to? Also is there any other screws on the carb that i need to be setting? I know the pictures upside down, sorry. Edited June 23, 2013 by sawtooth Quote Link to comment Share on other sites More sharing options...
0007 Posted June 22, 2013 Report Share Posted June 22, 2013 (edited) If indeed it is doing this it's what I call "Hanging up on the pilot jet" Meaning the pilot circuit is lean, and it will ring ding ding ding at well above idle for a few seconds before dropping down to idle speed Does it eventually drop to idle? If so Low fuel height Partially blocked pilot jet Air leak at intake Leaking crank seals So it would start with a proper carb service, I see the intake manifold clamp is not on straight, it may indicate that this has been apart recently? Yes the red arrow is idle speed, the other is air screw, start at 2 turns out Edited June 22, 2013 by 0007 Quote Link to comment Share on other sites More sharing options...
dombush Posted June 22, 2013 Report Share Posted June 22, 2013 +1 on all of those suggestions also just check the slide is returning positively. Check that the jetting values and needle type and clip position is somewhere close to standard. Dom Quote Link to comment Share on other sites More sharing options...
lineaway Posted June 23, 2013 Report Share Posted June 23, 2013 Are you sure the slide cap is tight? Sure looks loose upside down! Quote Link to comment Share on other sites More sharing options...
sawtooth Posted June 23, 2013 Author Report Share Posted June 23, 2013 Yes it does return to idle eventually and does alot of ring ding dinging first. Am pretty cluelesss when it comes to setting the carb up are there and guides kicking around that'll help me out? Quote Link to comment Share on other sites More sharing options...
sawtooth Posted June 23, 2013 Author Report Share Posted June 23, 2013 (edited) Have taken the carb out but not really sure what i'm looking for here tbh. Heres two pictures showing what its like with the throttle closed: Please click images for larger view. This pipe is almost melted shut, could that have anything to do with it? Also found that the part the floats lift up is a little stiff to get moving from its lower position, is that correct? See video: http://www.youtube.com/watch?v=GPuvJE0nWvg&feature=em-upload_owner Other than that, is there anything else I can check whilst its off? Please be descriptive as am not all that clued up here :-( If thats it for the carb i'll start looking at crank seals? The engine does sound like its needs the main bearings doing, that wouldnt cause hanging revs would it? Edited June 23, 2013 by sawtooth Quote Link to comment Share on other sites More sharing options...
lineaway Posted June 23, 2013 Report Share Posted June 23, 2013 By the way the 2007 had a keihin carb, sure it`s not an `06? Quote Link to comment Share on other sites More sharing options...
sawtooth Posted June 23, 2013 Author Report Share Posted June 23, 2013 (edited) Here's a couple of pics, 2007? ' Edited June 23, 2013 by sawtooth Quote Link to comment Share on other sites More sharing options...
sawtooth Posted June 23, 2013 Author Report Share Posted June 23, 2013 (edited) If indeed it is doing this it's what I call "Hanging up on the pilot jet" Meaning the pilot circuit is lean, and it will ring ding ding ding at well above idle for a few seconds before dropping down to idle speed Does it eventually drop to idle? If so Low fuel height Partially blocked pilot jet Air leak at intake Leaking crank seals So it would start with a proper carb service, I see the intake manifold clamp is not on straight, it may indicate that this has been apart recently? Yes the red arrow is idle speed, the other is air screw, start at 2 turns out Low fuel height, whats meant by this and how can i check it? Blocked pilot, have taken it out and it looks clear Air leak at intake, have clamped up the jubilee clip tight, anything else to check here? Leaking crank seals, how can i check that? I have access to an ultrasonic cleaner, worth dropping the carb in there for a bit? Just checked and i believe the pilot is 50 and the main 150, that right? Edited June 23, 2013 by sawtooth Quote Link to comment Share on other sites More sharing options...
0007 Posted June 23, 2013 Report Share Posted June 23, 2013 Check the beta thread sticky for carb setup, but I assume it ran at some point, I wouldn't adjust the float height just yet unless you know someone else messed with it just prior to it developing this issue Pull the needle and make sure there is no debris blocking fuel flow Make sure the manifold has no cracks and the gasket surface is normal looking, the bolts are tight Leaking crank seals would produce some goo on the mag side and would consume transmission oil on the other I wouldn't worry about jetting, look for something that has changed, not all things that were there when the bike ran properly Quote Link to comment Share on other sites More sharing options...
sawtooth Posted June 23, 2013 Author Report Share Posted June 23, 2013 Thats the thing, ive only just bought it, it seemed ok on a quick test ride hadn't been on a trials bike for a few years so I didn't pick up on the over revving until I got it home and took it for a proper ride. I cant see any debris in the carb at all now so will check the inlet manifold for cracks and then move on to crank seals. Quote Link to comment Share on other sites More sharing options...
dan williams Posted June 24, 2013 Report Share Posted June 24, 2013 If the pilot jet is 50 something's odd. Stock was a 30 and most people around New England near sea level changed to a 27.5. I believe the stock main is a 140. Before you go after the crank seals check the intake manifold for splits and make sure there are no casting defects in the inlet tract. Check the reeds while you have it apart. Reed petals don't need to be sitting absolutely flat as air pressure will close them but they shouldn't be frayed or cracked/broken. When you shut the idle screw all the way down the engine should just die on zero throttle. The other screw is an air intake for the pilot circuit in the carb. It's fed from one of the holes in the intake bell. When you clean the carb remember to run compressed air through the carb body after all the screws, jets, fiddly bits are out. I find it best to just disassemble on a paper towel so I don't lose any pieces. Don't run wire or anything harder than monofilament fishing line through a jet as you can scratch it and change the jet size. The tubes on the side that get melted are vents for the float bowl and are the cause of the famous Beta peeing gas syndrome. Nipper a small hole in the tube about halfway up the carb body to stop the carb from leaking. Quote Link to comment Share on other sites More sharing options...
betabonkers Posted June 24, 2013 Report Share Posted June 24, 2013 By the way the 2007 had a keihin carb, sure it`s not an `06? By the way the 2007 had a keihin carb, sure it`s not an `06? the o7 had a mikuni not a keihen Quote Link to comment Share on other sites More sharing options...
sawtooth Posted June 24, 2013 Author Report Share Posted June 24, 2013 (edited) My mistake, now the pilot is clean I can see its a 30. Reeds look OK too. Have replaced the rubber boot between the carb and engine with a new one and so far in the garden that seems to have made loads of difference, I think its almost back to normal. Will try raising the floats a little too if that might help? Also any pics of modding the vent tubes to stop the dam fuel leaking? Edited June 24, 2013 by sawtooth Quote Link to comment Share on other sites More sharing options...
0007 Posted June 24, 2013 Report Share Posted June 24, 2013 Well from a mechanical perspective it's fixed to its not The likelyhood of you having a leaking intake AND a second problem with the same symptom is very slim Something seems fishy if the bike ran well previously then adjusting the float height is not a repair Look for cause and effect, changing the effect by adjusting something that is not the cause is not going to work, it just gets you further from the cause by masking the symptom/effect if you know what I mean 1 Quote Link to comment Share on other sites More sharing options...
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