Leftyno1 Posted March 3, 2016 Share Posted March 3, 2016 Hello Well engine rebored etc etc and refitted with a brand new Mikuni TM 28 ss 418 flat slide carb fitted as well, Bike starts but idles at 2500 rpm idle screw is all the way out and turning mixture screw has no effect have checked with WD 40 for air leaks everywhere (none found) has new air filter fitted and have stripped carb at least 10 times . Float height is set at 22 mm as per factory setting and is running with a 240 main jet ( should not effect idle anyway) any clues to fault appreciated . Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 3, 2016 Moderator Share Posted March 3, 2016 Did you squirt the wd over the crank seals? Link to comment Share on other sites More sharing options...
Leftyno1 Posted March 3, 2016 Author Share Posted March 3, 2016 Yes have sprayed all over including crank seals, one time of many Carb strips I got the bike idling perfect but that lasted 2 miles, i am stumped as it is not complicated but can I find the problem , no bloody annoying. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 3, 2016 Moderator Share Posted March 3, 2016 Ok. You said you have got the idle down once and it lasted 2 miles. First a really important question. Was the carb from china? If it was that is 99% of the problem cos their shite.,, first class grade A garbage. Otherwise. What did you do? Really think on it. Not just i rode it a bit. Did you change the float height? Any gaskets? Was the engine hot/cold? Air filter seated? Really csi style debreif yourself as it could/will be something tiny. Link to comment Share on other sites More sharing options...
Leftyno1 Posted March 3, 2016 Author Share Posted March 3, 2016 I have checked carb for being a fake and I am sure compared to Fake carbs I have seen on Google and info that it is genuine but even fakes are getting good,so i can not be a 100% on that question as that was my first thought as well but your right am going to have to CSI the details to get to the truth as stripping carb and rebuilding is not doing it .It will be obvious when I find it LOL . The three things that come to mind at moment are that bowl sits into a recess on bottom of carb, so will ring mikuni UK as I have set height from bottom of recess 22 mm and I need to be 100% certain that carb is genuine.. And though it is a new filter I fitted no non set gasket sealant where it slides in ? will get back to you. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 3, 2016 Moderator Share Posted March 3, 2016 Its not very scientific but have you changed the float height (so there is more fuel) to check the effect. Link to comment Share on other sites More sharing options...
blackhat250 Posted March 3, 2016 Share Posted March 3, 2016 Disconect the throttle cable, ,see if it idles, then raise slide with the idle screw, ,just to illiminate cable snag, Link to comment Share on other sites More sharing options...
Leftyno1 Posted March 4, 2016 Author Share Posted March 4, 2016 Not had a lot of time last couple of days but found time to Disconnect throttle cable and made sure it was seated into top of Carburetor where it joins also fitted foam to air filter seat where it slides in so air is pulled through New filter neither made any difference so two things eliminated. Link to comment Share on other sites More sharing options...
Leftyno1 Posted March 11, 2016 Author Share Posted March 11, 2016 Well changed float height to 20mm and changed idle Jet to one from old Carb (same make carb snatching at straws really) put it all back together and Bike ran like a charm idle set at 1500rpm, took the bike for a 6 mile ride all was good, started bike up in morning and it cut out when revved ,now bike is wanting to stall ,complete opposite of high idle. Bike if revved over 5000rpm it floods and I have to remove Plug and clean as it is so wet, can the be the float height ,considering bike is not complicated LOL, it is sure messing me about, any clues anyone. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 11, 2016 Moderator Share Posted March 11, 2016 Idle jet does little over 2000 rpm let alone 5. 1mm of float height wont do much either. Have you stripped the choke down to check it. Bet you didnt note the idle jet sizes either. Link to comment Share on other sites More sharing options...
Leftyno1 Posted March 11, 2016 Author Share Posted March 11, 2016 well its a brand new Carburetor so didn't think to strip choke down, your right did not check idle jet sizes as did not have magnifying glass at time lol, Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 11, 2016 Moderator Share Posted March 11, 2016 Assumption is the....... yadda yadda. Just because its new doesent mean its right. The choke draws fuel from the float chamber to richen the mixture. Bit of rubbish in there would mess you about. Not many other parts of a carb can drasticly affect the engine from lean to rich as much as the choke. We may be moving foreward. Before pulling it apart what effect does the choke have now. Link to comment Share on other sites More sharing options...
Leftyno1 Posted March 11, 2016 Author Share Posted March 11, 2016 Agree completely about assumption ( I was taught assumption is the mother of all F***ups) so yes will not discount choke, at moment putting choke on while engine running stops bike,do not use it to start either as will start without (very hot here), but yesterday when bike stopped after running perfect I noticed Choke was on and this is second time this has happened ,and I certainly did not put choke on either time , so something suspicious for sure. 1 Link to comment Share on other sites More sharing options...
Leftyno1 Posted March 11, 2016 Author Share Posted March 11, 2016 Idle Jet is size = 15 Link to comment Share on other sites More sharing options...
Leftyno1 Posted April 7, 2016 Author Share Posted April 7, 2016 Well Bike is sorted ticking over lovely and have taken bike on a couple of nice runs with no drama , I dle problem was a very slightly blocked idle jet , soaked over night and cleaned out then blew through with air ,going to put some miles on bike now to finish running in, thanks everyone for help. 4 Link to comment Share on other sites More sharing options...
Moderator Cynic Posted April 7, 2016 Moderator Share Posted April 7, 2016 See something so tiny... Glad its sorted and thx for the feedback. Link to comment Share on other sites More sharing options...
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