toman21 Posted July 6, 2013 Report Share Posted July 6, 2013 (edited) Hi there, i just found out that if i let my bike return to idle for even 5 secs and then as fast as i can open the throttle wide open there is always a very noticeable delay. So i thought it could be the fuel screw being to rich or lean making the "WWhhhaaa" noise, so i then tried from 3.5 turns out to 2 turns out. Moving the screw in segments of 22.5 degrees so i wouldn't miss anything, however that didn't work. Also when testing it i had the idle screw up higher than normal so its not that the bikes about to cut out. There is no delay if you are "revving" it right up one after another or even if you aggressively (yet not as fast as you) blip the throttle from idle. Could it be a blocked pilot? There is no air leaks Air filter is clean and oiled Carb = Dellorto Phbl 26 Pilot = 33 Main 118 Any ideas? Thanks Edited July 6, 2013 by toman21 Quote Link to comment Share on other sites More sharing options...
copemech Posted July 6, 2013 Report Share Posted July 6, 2013 Is this bike a 125? Quote Link to comment Share on other sites More sharing options...
toman21 Posted July 6, 2013 Author Report Share Posted July 6, 2013 (edited) Nup, its a 290. Seems weird as the jets are in range. Edited July 6, 2013 by toman21 Quote Link to comment Share on other sites More sharing options...
dadof2 Posted July 6, 2013 Report Share Posted July 6, 2013 Bike model and date would help. This is the poor pick up you get if the pilot is clogged, pilot way too rich, too little cutaway on the throttle slide or throttle slide in wrong way round. Quote Link to comment Share on other sites More sharing options...
toman21 Posted July 6, 2013 Author Report Share Posted July 6, 2013 Bike is a Sherco 2008 2.9. I will check the slide is stock and is it even possible to put it in the wrong way? It cant be rich on a 33 pilot at 3 turns out and it still done it? Ill check the pilot tomorrow also. Thanks Quote Link to comment Share on other sites More sharing options...
stork955 Posted July 6, 2013 Report Share Posted July 6, 2013 G'day, isn't the idle screw on the Delloroto's an air screw? (out = lean)? If so it sounds like you are going the wrong way. I can vaguely remember the setting for those is a half turn out or something like that. Someone will chime in and give the factory spec. Also, clean the exhaust. By now it will be well choked up. Cheers, Stork Quote Link to comment Share on other sites More sharing options...
toman21 Posted July 6, 2013 Author Report Share Posted July 6, 2013 (edited) No, its a fuel screw, 3 - 3.5 turns out is normal. I would like to clean the exhaust however am not sure how to, is there anything that you can put in the exhaust that will brake up the carbon that doesn't damage the aluminium? Edited July 7, 2013 by toman21 Quote Link to comment Share on other sites More sharing options...
0007 Posted July 7, 2013 Report Share Posted July 7, 2013 I wouldn't jump to conclusions, manufacturers don't tune engines to respond to rapid throttle openings with no load The is no application for this If the bike responds well when riding it in gear I would quit looking for problems A lot of bikes, particularly four strokes don't do well at this, again, no reason If they were tuned for instant throttle response with no load there would likely be a problem with it when there is load Japanese engineers I have worked with say "No Meaning" about issues like this Quote Link to comment Share on other sites More sharing options...
copemech Posted July 7, 2013 Report Share Posted July 7, 2013 (edited) I wouldn't jump to conclusions, manufacturers don't tune engines to respond to rapid throttle openings with no load The is no application for this If the bike responds well when riding it in gear I would quit looking for problems A lot of bikes, particularly four strokes don't do well at this, again, no reason If they were tuned for instant throttle response with no load there would likely be a problem with it when there is load Japanese engineers I have worked with say "No Meaning" about issues like this Agree with 007 on this, as not normal operation, however typical this may be on a 125 due to ratio of intake vs displacement, on a 2.9 they will normally pick up and respond without a bog period if properly jetted. Long story made short, it seems to me that fuel changes over the years have effected jetting requirements and a 33 pilot may no longer be sufficient. Seems many in UK are up to 36 commonly, and I would suggest the change. As example, my "07 came with a 30 pilot, and it was soo weak it would not lift the front wheel! So 3 points may well change the bike, still adjust mix screw to desireable position, which mat well be in 2.5-3.0 range. M2C Edited July 7, 2013 by copemech Quote Link to comment Share on other sites More sharing options...
toman21 Posted July 7, 2013 Author Report Share Posted July 7, 2013 I have a 36 pilot and a 122 main already, so I'll give it a try if cleaning the carb doesn't work. Could water in the fuel cause it maybe? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted July 7, 2013 Report Share Posted July 7, 2013 Water in fuel could cause it - it tends to block the slow running jet Quote Link to comment Share on other sites More sharing options...
toman21 Posted July 8, 2013 Author Report Share Posted July 8, 2013 (edited) Right, i cleaned the carb/jets and put fresh fuel in the tank(this was still on the 33/188)... no difference. The bog got worst the the leaner the fuel screw was from 3.5 but still done it at 3.5. It turns out i have a 35 pilot and 122 main in my spare parts box. So i put them in and tried it at 3.5 turns out... 90% of the time there was no bog, then i put the screw to 3 turns out and the bog happen more. Seems to have fixed it mostly , but i am thinking of trying a 36 pilot to see if the bog never happens at all. Would it be all normal to use a 35/36 pilot with a 122 main? I have just rebuilt the top end and the compression has increased could this have been the reason that it needs to be more rich? Edited July 8, 2013 by toman21 Quote Link to comment Share on other sites More sharing options...
tony27 Posted July 8, 2013 Report Share Posted July 8, 2013 When I ran the standard dellorto on my 290 I thought I ran a 36 pilot but just looking having a look at the carb showed me that it was a 30, the 36 must be in the box of jets. Main jet was a 124. I haven't run with the dellorto for years, would be from before alcohol got added to our fuel. My suggestion is to fit a 36 like Cope says & see if you end up with more range of adjustment Quote Link to comment Share on other sites More sharing options...
copemech Posted July 9, 2013 Report Share Posted July 9, 2013 I do not know that you necessarily need the larger main, as the 118 should allow it to rev out cleanly and quickly which is ok. One point on the low speed jet does not make a lot of difference, say 35 vs 36, but may be just enough. Normally takes 2 sizes for much difference! Quote Link to comment Share on other sites More sharing options...
toman21 Posted July 9, 2013 Author Report Share Posted July 9, 2013 I'v got a 36 and 120 coming. I'll report back after iv tested it. Quote Link to comment Share on other sites More sharing options...
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