rear cyl out at idle

[hamptoncarmody]

Hi I have a 86 xz400. I live in New Zealand. I,ve done around 2000 ks on this bike ,had it for about 3 mths . My problem is, the rear?cyl cut out at idle sometimes up to about 4000 revs. Needless to say it didn,t do it when I bought it . Different methods will cxure it for a while , drain carbs cured 1st time but not again. After a 60k run its crook but often it will come right all round the city for the day and then be crook on return home. I,ve just sprayed the inside and out of the carbs with crc carb r cleaner as per instructions. Success but only for 15k , back to same old same old.Ive read rov web site thoroughly. Do 400s have a rev limiter and would that trouble restrict itself ?to that rev range. Any help would be appreciated. I really like this bike, have just a 2nd hand fairing. What thic about oil filler? ?seeya .

[Walt_M.]

Are you absolutely sure it is the rear cylinder? The rev limiter cuts out the front. My 550 had the rev limiter problem, I think, and it made me a little bit mental until I disconnected it.
You might also want to do a carb synch.

[Rick G]

Do the easy stuff first , cut out the rev limiter and sync the carbs . If that dosen't do it, you may have to dip them. Keep us posted. What is the top speed on a 400?

[hamptoncarmody]

Well I,ve just spent most of the day stripping the carbs and cleaning them.I cut the rev limiter cable , made no difference.I was reading "jarheads" thread and the carb chappy said it was probably the pilot jet, so I decided to give everything a damn good cleaning.So 1.5 cans of carb cleaner later carbs look great and run s on two cyls again! I took them out as a set just like I read in the forum.  I,ll reserve judjement till I get to work tommorrow, which is usually the distance it takes to get crook.I wound it out a bit today, got to 150ks@8500 rpm. It cruises easily at our speed limit of 100ks at 6000. It,s quite easy to get 110 120 ks and get in trouble with the law, more so now I,ve fitted my 2nd hand fairing , good score off the trademe $40 , correct colour for my bike and all. I enjoy this site a lot and its a great help. Keep it up guys. seeya.