Baffled Posted June 25, 2015 Share Posted June 25, 2015 My 600 Diversion with low miles will start on full choke and rev at 3000. However if I touch the accelerator it cuts out. I have cleaned carburetor jets (it was very clean anyway), put new fuel in but still the same problem. I have also run it with fuel tank off and can hear the pump run and see it take fuel from temporary feed. While it runs fine on full choke it will cut out when I put the choke in even when warm and does not seem to want to take any load Has anyone any suggestions as to what could be causing this problem? Everything I look at seems healthy so could it be some electronic problem? All help appreciated as I am baffled. Link to comment Share on other sites More sharing options...
blackhat250 Posted June 25, 2015 Share Posted June 25, 2015 Ok " the pilot jet takes over from the choke , it feeds the first 1/4 of throttle, as venture gathers , its the needle jet / needle that feeds till w.o.t, . then its main jet, s so I suggest you remove the pilots , and really clean them , is it Mikuni, or Keihin carbs, Check all vacume hoses , are on , no air leaks,,, AND air box is fitted , this is a must,,, Link to comment Share on other sites More sharing options...
Baffled Posted June 25, 2015 Author Share Posted June 25, 2015 Thank you for your reply. I will look at the pilot jets again although what puzzled me was was how clean the carbs were, Mikuni by the way. I could see no sign of any dirt or build up of residue in the jets or anywhere else. I tested after cleaning with the airbox off and petrol fed by an extension feed so I could see what was happening. I'll clean again and try with the airbox back on. It was strange that the behaviour was exactly the same as it was before I stripped it down. I will let you know how it is after I put it back together. Thanks again. Link to comment Share on other sites More sharing options...
Baffled Posted July 2, 2015 Author Share Posted July 2, 2015 FIXEDThe pilot jets looked clean but the very fine hole at the top was blocked so your analysis was spot on. Once cleaned the bike would start and accelerate. Knowing what the pilot jets do made all the difference. I still have some problems as it will sometimes cut out and I need to set the fuel to prime to get it to run so I think I have a fuel pump or vacuum issue but at least it will run now. 2 Link to comment Share on other sites More sharing options...
Silkk Posted July 3, 2015 Share Posted July 3, 2015 With the Mikuni carbs I have noticed that if the balancing pipe isnt fitted correctly then it looses pressure and doesnt balance. Either side of the fuel intake pipe, there should be 2 other ports for a short hose, check that as I had the same problem on my FZR. Not too sure on the XJ, but with mine, when the tap is set to off, then the fuel pump also turns itself off ..... although cant find an electric switch, so guessing its a gravity fed pump and switch. When priming after engine is cut, if you turn the tap off and back on, can you hear the pump clicking to prime itself ? Link to comment Share on other sites More sharing options...
mike1949 Posted July 3, 2015 Share Posted July 3, 2015 FIXEDThe pilot jets looked clean but the very fine hole at the top was blocked so your analysis was spot on. Once cleaned the bike would start and accelerate. Knowing what the pilot jets do made all the difference. I still have some problems as it will sometimes cut out and I need to set the fuel to prime to get it to run so I think I have a fuel pump or vacuum issue but at least it will run now.Glad you got it sorted out Baffled.But believe it or not I had the same bike as you and after ten years of commuting to work in all types of weather with the bike left outside all the time the one thing I never had any trouble with is the carbs. Link to comment Share on other sites More sharing options...
fabiostar Posted July 4, 2015 Share Posted July 4, 2015 i had problems with mine running rough and it turned out the carb rubbers were cracked. not enough to see but when i had it ticking over i sprayed easy start round the rubbers and the revs went up. once i took them of they were cracked under the clips that hold them on. £23 on ebay got me a new set and problem sorted. Link to comment Share on other sites More sharing options...
Baffled Posted July 7, 2015 Author Share Posted July 7, 2015 My fuel tap has 3 positions, on, prime and reserve and my fuel pump is electric and lcan hear it ticking when l try to start the bike. The bike ran well after l took your advice and re-cleaned the pilot jets. I then took it for an MOT and it cut out on the way but started when l set the fuel to prime. I left it on prime for the test and took it for a run afterwards turning the tap back to run. I did several miles and it ran well then stopped at the shops. After starting again the bike ran for a couple of hundred yards before cutting out again. Back on prime it started and l left on prime to get home. As l understand it, prime let's the fuel flow freely and run requires the vacuum from cylinder one to get the fuel to run although l don't know how this works. The vacuum tube seems in good condition (carb rubbers also look good), petrol pump seems to run but obviously something is not right. My battery is not good and won't start the bike after a limited number of attempts even when freshly charged so needs replacing. I suppose that could be a cause but l think l need to check the pump and vacuum to the fuel tap to fix the problem.Thank you all for your help. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted July 7, 2015 Moderator Share Posted July 7, 2015 The tap has a diaphram in it. It may be getting good vac from the carbs but the tap may need work.They are ok. I have had 2 go on me and each time running on prime kept me going. Parts are not expensive and its relatively simple to do once the tank is empty. Link to comment Share on other sites More sharing options...
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