YZ85 puking oil

[sodflyer]

Hi all...first post here and first time getting back into riding after 12 years off from it. Last week I bought a pair of 04 YZ's one for me ( yz250 ) and one for my son ( yz85 ). We have enough time for them to be broke in by now however my son's 85 after riding has a good ammount of oil from the tail pipe running down it and enough so that it's coating the swing arm as well.... I have not changed anything on the carb yet but I am running premo gas @ 32:1 ratio here at 5500 feet in Colorado. At first was thinking it was due to it being a new engine or it was his slow riding style but it will still puke it out even if Im riding the crap out of it... what do you guys think I should tune first? My 250 running the same setup does not have this problem... thanks for any help here! Jeff.

 

[Chili]

We haven't had one but I've seen many threads here over the last few years about how rich the stock YZ85 jetting is, this combined with your higher altitude is making the problem even worse. Time to rejet that bike.

 

[sodflyer]

Ok thanks for the info.... I have some jets that came with the bike.... 178,172 and 52, 48... witch ones do I change out and what number for a leaner set? Thanks Jeff.

 

[1966mustang]

well it depends on wut you got in it now. if they are between the ones you got now then 172 and 48 are the ones to use. You can find the numbers of the ones youve got installed stamped on the side of them.

 

[Chili]

sodflyer do a search for jetting and you'll get more info to keep you busy for the next few years. Also check out the carb tuning article at www.ericgorr.com. In the archived threads portion of this site there is a few jetting threads that are worth their weight in gold.

 

[xcracer725]

i had this problem on my yz85 after i got my new fmf silencer but it stopped after some time and yes that bike does run rich

 

[sodflyer]

Thanks, Before tearing into the carb lastnight I turned the main in about 1/4 turn and ran the bike for a few min....after this I did not see any oil pumping out of the back... I will be able to get a better feel for it this weekend. Jeff.