growler Posted August 20, 2010 Share Posted August 20, 2010 hi all, first of all i would like to say hello and congrats on a great site. i am sorry that in my first post i need some help. i have a 1992 535 that i bought about a month ago,it has only done 8000 miles,but when i leave it standing for a day or two and then go to start it,it usually only fires up on one cylinder either front or back,runs on that cylinder for a few secs then stops. the plugs and battery are new and when it runs properly it will run all day without missing a beat. what i have narrowed it down to is that when i turn the ignition on i could only hear the pump tick once then stop, so i removed the carb float sides and the carbs are empty and the floats are stuck up in the closed position,pull them down and replace the sides and the pump ticks away and fills them,then no problems away it goes. my main question is does the pump create a vaccuum when it is off making the shut off valves stick on closed,i have taken the float and valves off and cleaned them,they seem to be in good condition. forgot to mention i have found out that the reason it only fires on one cylinder is because that will be from the carb that still has fuel left in it. any one else had this problem? thanks in advance. Link to comment Share on other sites More sharing options...
webi Posted August 20, 2010 Share Posted August 20, 2010 hi welcome to the forums hope you enjoy it sorry i cant help with your problem =( Link to comment Share on other sites More sharing options...
jimm Posted August 20, 2010 Share Posted August 20, 2010 The 535 is becoming a classic! Anyway, yours is almost 20 years only and has only done 8k, so its spent a lot of time sitting not going anywhere, so I'd suspect gum formation (from the fuel) in the carbs. The fact that this happens after its sat for a few days would support this. The fuel pump shouldn't pull a vacuum, but it could be that when you park up after a ride, the heat 'soaks' the carbs and the fuel in them expands, forcing the float hard up, and then it sticks. Or the carb has expanded in the heat, and then cools down, trapping the float...whatever the reason, it shouldn't stick! Only real remedy is to remove and strip the carbs down and clean them out very thoroughly, even if they look clean now. Gum can be hard to see...it can be a bit like a thin coat of varnish. I know you've cleaned them already, but what did you clean them with? You can buy 'carb cleaner' which should help get rid of gum, but beware that some of these are caustic and even if they're not, they could damage and plastic parts (like the float), gaskets etc. I'd also clean out the needle valve parts in the same way, although DON'T go poking a pipe cleaner or something into it as you could damage the valve seat. I know you said it was the floats that were sticking, but its likely that the needle valve is also gummed up and could stick as well - same end result. Sometimes there are little rubber seals on the needle valve - this could get damaged by the cleaner also. The carbs are 20 years old, its really a strip down job, and you should really see if you can get a gasket/refurbish kit for it - you'd like to think that this was something that a Yammie dealer could supply. Alternatively, have search around locally and see if there are any specialist shops that would service the carbs for you. Don't think I'd trust this to your average dealer...they'd just want to bolt on new ones Which might actually be worth pricing..out of interest. Have fun! Jim Link to comment Share on other sites More sharing options...
growler Posted August 20, 2010 Author Share Posted August 20, 2010 The 535 is becoming a classic! Anyway, yours is almost 20 years only and has only done 8k, so its spent a lot of time sitting not going anywhere, so I'd suspect gum formation (from the fuel) in the carbs. The fact that this happens after its sat for a few days would support this. The fuel pump shouldn't pull a vacuum, but it could be that when you park up after a ride, the heat 'soaks' the carbs and the fuel in them expands, forcing the float hard up, and then it sticks. Or the carb has expanded in the heat, and then cools down, trapping the float...whatever the reason, it shouldn't stick! Only real remedy is to remove and strip the carbs down and clean them out very thoroughly, even if they look clean now. Gum can be hard to see...it can be a bit like a thin coat of varnish. I know you've cleaned them already, but what did you clean them with? You can buy 'carb cleaner' which should help get rid of gum, but beware that some of these are caustic and even if they're not, they could damage and plastic parts (like the float), gaskets etc. I'd also clean out the needle valve parts in the same way, although DON'T go poking a pipe cleaner or something into it as you could damage the valve seat. I know you said it was the floats that were sticking, but its likely that the needle valve is also gummed up and could stick as well - same end result. Sometimes there are little rubber seals on the needle valve - this could get damaged by the cleaner also. The carbs are 20 years old, its really a strip down job, and you should really see if you can get a gasket/refurbish kit for it - you'd like to think that this was something that a Yammie dealer could supply. Alternatively, have search around locally and see if there are any specialist shops that would service the carbs for you. Don't think I'd trust this to your average dealer...they'd just want to bolt on new ones Which might actually be worth pricing..out of interest. Have fun! Jim hi jim, what a great reply,plenty to think about there. i have been reluctant to take the carbs off and strip them yet as the previous owner was using the bike regulary up until i bought it,and it runs smoothly and ticks over like a sewing machine,the only thing i have done to it is give it a good clean and filled it with fuel from a peva garage which could be the problem. the needle jet you mentioned do have tiny rubber tips but they look good and dont feel soft,i think i will drain the fuel and try to get some nylon type valves i never had any trouble with them on previous bikes,also the heat expansion is worth thinking about as the heat from the engine does keep you warm when you stop for a while after a good ride. i will keep you informed how i get on with it when i get some new needle jets. p.s can you recommend a good carb cleaner/addative. regards, alan. Link to comment Share on other sites More sharing options...
xv535 Posted September 9, 2010 Share Posted September 9, 2010 I ride a 535 also and I have started to have some carb problems that he dealer can not solve. The engine misses every now and then, and there is a popping sound. We have checked the obvious things, put in new jets, checked the carb for air leaks but still have not solved the problem. In frustration I asked the dealer to track down a set of new carbs. The price of the new carbs was $1500. I am not sure what that is in pounds but it is more than I am prepared to pay. RM Link to comment Share on other sites More sharing options...
growler Posted September 15, 2010 Author Share Posted September 15, 2010 I ride a 535 also and I have started to have some carb problems that he dealer can not solve. The engine misses every now and then, and there is a popping sound. We have checked the obvious things, put in new jets, checked the carb for air leaks but still have not solved the problem. In frustration I asked the dealer to track down a set of new carbs. The price of the new carbs was $1500. I am not sure what that is in pounds but it is more than I am prepared to pay. RM hi, just noticed a set of carbs on ebay,but they are over here in the u.k. he may post over there to you. item number is 280562650557 good luck. Link to comment Share on other sites More sharing options...
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