1987 exciter 570 butterfly carbs

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rat12278

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I have a 1987 ex 570 I'm cleaning the carbs on and replacing all the fuel lines. I have read there was a needle update and I'm not sure what it is or how to know mine has been done. it still has the mikuni butterfly carbs on it and has about 5,800 miles. thanks. just have about enough snow to ride so want to fix asap. thanks
 
I thought the 87 Carb update was to pull the butterfly carbs and run round slide Mikuni's. The 87 I had years back had the round slides.
 
94max said:
Yamaha did update those sleds to Mik roundslides.
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Im not sure, that's why i kinda asked the question. I cleaned the carbs last year and it ran good for awhile and then kinda bogged at higher rpm. So I'm replacing the fuel lines and pump, so there is no more crap to clog the carbs. It sat in a shed for 15 year's but ran great at first. Still started great and was rideable.
 
rat12278 said:
Im not sure, that's why i kinda asked the question. I cleaned the carbs last year and it ran good for awhile and then kinda bogged at higher rpm. So I'm replacing the fuel lines and pump, so there is no more crap to clog the carbs. It sat in a shed for 15 year's but ran great at first. Still started great and was rideable.
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Any good Yamaha Dealer should be able to run the VIN and see what updates it has and what updated should have been done.
 
ok. it runs and starts good but sounds a little rough at high speed with track off the ground and not reaching top rpm. all fuel lines and fuel pump are new. looking in to clutching. where can I find the right primary spring for this, if you look it up at a parts store it gives 2 different springs and I don't know witch one I need. thanks.
 
I need a purple/white spring for the primary clutch but I can't find one anywhere. Please help, Mabey there's a alternate part?
 
Mr. sled, thanks for the chart. I see on the chart for the secondary its says what hole to put the spring in (A2) but what does the (50) mean after the (A2)? also when I put the secondary back together do I line up to the first ramp when putting it together or do I give it another 1/3 of a turn and create more pressure on the spring. Thanks a lot for the info
 
rat12278 said:
Mr. sled, thanks for the chart. I see on the chart for the secondary its says what hole to put the spring in (A2) but what does the (50) mean after the (A2)? also when I put the secondary back together do I line up to the first ramp when putting it together or do I give it another 1/3 of a turn and create more pressure on the spring. Thanks a lot for the info
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You have to give it a turn to the next ramp as you stated to preload the spring as you twist it. I would guess the A-2 is 50 deg but I am not certain. I pulled the info from the tech manuals.
 
I did what you said and seems pretty good. have not a chance to open it up yet but lifts the skis in the yard. thanks again
 
list of updates for the 87 EX was CDI box, and carbs to start them the list starts for fixes to issues .... since you still have the butteryfly carbs leave them they are great carbs as long as the mid range is rich enough
 
The sled starts and runs great but if you punch the throttle it will rev up to about 7k rpms and then slow to about 4500 rpms and stay there until you let off but then if you hit it again it will rev up for a second or 2 they back to 4500 rpm. I replaced both clutch springs and set the secondary to factory settings. I put a brand new fuel pump in also. I also looked on other forums and they said that one of the rubber plugs in the carb should be plugging the hole where the pilot jet is. I tried that and it would only run if you feather the heck out of the choke. witch cant be right. Thanks for any help. ( 1987 Yamaha exciter 570l, with butter fly carbs)
 
when i get some time i will dig threw my old notes on the EX butterfly carbs the rubber plugs are different than the phazer carbs
 
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