August 17, 201016 yr Just a quickie how do you tell what pilot jet is in the carb. I was at a trial the other week and the bike sounded like it was hunting. To cut a long story short, someone there spotted this and adjusted the mixture srew about 3.5 turns from fully in and suggested i get a 33 pilot jet as id prob be running a 30. I just dont want to buy a 33 if i may already have one in. Oh the bikes an 04 250 sherco All help appreciated!!!
August 18, 201016 yr No need to remove the jet, the number is stamped on the head in plain sight. Pilot jet is the jet towards the front of the carb closest to the main body
August 18, 201016 yr There is a good possibility it may be slightly blocked so take it out anyway and blow it through with a air line.
August 18, 201016 yr Author Thanks for all the help guys. I'll split the carb and give it all a good clean out. Ive had this prob before but it turned out to be the angled throttle guide tube on top of the carb that was snapped. Its suprising how little things cause problems. If the cleaning doesnt work is it adviseable to get a different pilot jet??
August 19, 201016 yr Your advise is sound, yet you may indeed find you are on a 33 pilot, as a 30 makes things quite weak off the bottom. The fuels in many parts has changed over the years as well with the introduction of the ethanol(alcohol) blends. Many now run a larger 35-36 range jet on the later models, yet I cannot tell if this is purely a fuel issue or the year range of the bikes as I do not have an earlier model to directly compare. I ran a 33 nicely back in '03, yet my '07 2.9 was on a 38 prior to changing the carb to the Oko! Running the fuel screw out at 3.5 turns on a Dellorto is at the limits of its range of control. And on a Dellorto, the pilot jet also controls the transition circuit, whis is that totally unregulated(jet only) other little hole in the bore, so if your pilot jet is too big, even though you might be able to achieve a good idle with the fuel screw adjustment, it could turn a bit rich and blubber a bit at about 1/16 steady throttle during the transition to the needle. Back in the day, I had to go back to 32-33 range from 35 because of this. Add each bike and carb vary a bit, so no set rule here. My '07 was on 1.5 turns out with the 38, and worked perfect on our fuel! Adjust on the temps of the day, need more(out) when its cold.
August 23, 201016 yr Author Hi all took carb off gave it a good clean out found its already running a 33 pilot jet! Put it back on the bike and it continues to run the same thats with the mixture screw turned out 3.5 turns. Runs ok with choke on but cant leave that on when riding. Any suggestions???
August 24, 201016 yr Hi all took carb off gave it a good clean out found its already running a 33 pilot jet! Put it back on the bike and it continues to run the same thats with the mixture screw turned out 3.5 turns.Runs ok with choke on but cant leave that on when riding. Any suggestions??? Well, if you are sure the jets are clean, you could have an air leak. Specifically the crank seals, see recent post!
August 24, 201016 yr you need to make sure that everything is clean, carb, airbox and filter like cope said it might be the crack seals, easy way to check is to spray some carb cleaner around the flywheel and look for it be sucked. how did you clean the jets ??? it sound like fueling to me
August 24, 201016 yr Author I took the jets out and stuck a pin through them then blew them out with the air line. Not put a clean air filter in so will have to try that. Would a bigger jet not help or is a 33 adequate? My bros got an 07 125 cabby i could try swapping the carbs over and try that. I did that last time I was fault finding when I had the snapped throttle cable guide tube issue. Its frustrating when i dont have the knowledge on how it all works properly. Thanks again everyone for your inputs id be a bit lost with ou you
August 24, 201016 yr I took the jets out and stuck a pin through them then blew them out with the air line. Not put a clean air filter in so will have to try that. Would a bigger jet not help or is a 33 adequate? My bros got an 07 125 cabby i could try swapping the carbs over and try that. I did that last time I was fault finding when I had the snapped throttle cable guide tube issue. Its frustrating when i dont have the knowledge on how it all works properly. Thanks again everyone for your inputs id be a bit lost with ou you what was the fuel filter like?
August 24, 201016 yr Author The fuel filter seemed pretty clean it that got a blast out with the air line too when I had the carb stripped. what you thinking like?
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