Idle Problem

23 replies to this topic
  • Ga426owner

Posted June 19, 2006 - 06:21 AM


check the cold start plunger. If it isn't seating properly is will cause idle problems.

Bingo - this is what causes this 9 out of 10 times -
the hot start will have corrosion due to a not so great oem plastic fitting - keeping it from seating correctly. You have to clean this periodically and use some lithium grease in there.

ZipTy Racing makes a nice metal fitting to help alleviate this - periodic cleaning is key


Posted June 20, 2006 - 07:55 PM


I dropped my bike off to a guy that works on bikes for a living. He called me tonight and said that he had found a piece of rubber or something in a fuel passage. He has to take the carb to work tommorrow to get it out then he will call me if that takes care of the problem. I'm glad to hear that you finally got your idle problem figured out. I'm real eager to ride myself. I was wondering what the piece that Ga426owner was talking about is called so I can look it up? I'll keep you posted on my bike. Thanks.

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  • motoman_89

Posted January 06, 2007 - 08:24 PM


i also have a 98 yz400f that wont idel but mine also has no bottom end power and if u try to take off it will bog down and die and over heats. i am stilll workin on it to this day and its rilly starting to make me want to push it off a cliff. i have replaced every electrical component on the bike except for the tps but it have tested it and it tests good. i have cleaned and readjusted my carb three times. i call around and found out that if the bike dosent have at least 130psi of compression it wont run rite so i ran a compression test on in and it had 65 so i put a high comp rebuild kit in it and it brong it up to 95 so i took it to a shop and they ran a leak down test on it and said they think its leakin out the exaust so i pulled it apart and reseated all my valves and adjusted the valve clearance and that still didnt help. so the last thing i tryed was puring a stall amount of oil in the cylinder and ran another comp test on it and i got 150psi and i noticed that every time i pull the valve cover off there is no oil. so im thinkin i might have a problem with my oil pump or a cloged line or filter. but id say it wouldnt hurt to run a compression test on your bike and if anyone has any info that would help me i would greatly Appreciate it.


Posted January 08, 2007 - 12:42 PM


Where are you located in Indiana? I live in Danville. I can give you the name and number of a guy that does great work at a very fair price. Let me know if you want it. His specialty is YZF's. If nothing else he might have some good info to help you along.

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