my 1st post, maintenance on a 99 yz400f

5 replies to this topic
  • viggen

Posted July 13, 2005 - 03:35 PM


Last week I purchased a 99 yz400f after taking about 14yr leave from the hobby/sport. I think I got a good deal on the bike thus I couldn't pass it up

Anyways, what oil should I use? I have been told to not use synthetic oil just use 10-40 dyno oil? Any certian manufacturer? Is Castrol OK?? Change every 10 ish hrs?

Is there anything else I need to know on the bike? I was going to ride my 1986 TT 225 which has sat since 91 however like I said I couldn't pass this bike up.

I plan on doing more trail riding then track riding & am looking for trails in the Ohio area, Dayton is where I live.

  • 99wr400

Posted July 13, 2005 - 04:00 PM


Make sure to clean the air filter and change the oil filter along with the oil. I use honda 10w40 in my WR"400". Car oil has friction modifiers that can make your clutch slip. Other that that, the bikes are basically bullet proof. The top-ends last for years, and the stainless valves will likely outlast the bike. make sure the radiator's arent smashed, and the subframe is straight, other than that you wont need to worry about anything.

  • viggen

Posted July 13, 2005 - 05:45 PM


thank you!

So I need to stick with motorcycle oil & change the oil filter at every oil change

The radiator looks fine on the bike however the rear fram is partially broken. The spot the rear brake resevoir mount to the frams & the brush/boot gaurd is broken. I am going to try to have it re-welded & then possibly powdercoated. Or spend the $200 on the new rear frame

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  • Lukejt

Posted July 13, 2005 - 08:55 PM


Just go to Wal Mart or Costco and buy some Rotella T from Shell, 15w-40. It's heavy duty oil designed for diesel and big rigs. No friction modifiers. Sure, you'll get a million opinions on oil, but this stuff is real good and cheap too. Since you are going to change the oil often, every 300 miles or so I don't think you really need synthetic. I use synthetic in all my cars, but I'm running 5,000 miles per change.

The oil filter should be metal, and can be washed out a few times before replacing. Still good to have a spare or two.

I've read that green antifreeze is bad for aluminum (read about this on a Mercedes forum, I bought an old diesel on Ebay), my bike still has the green stuff and I do see some crap floating around. I've purchased the high end Zerol (orange, long life MB certified, MB uses a lot of aluminum radiators) and will change out the antifreeze on my bike ASAP. There is a product called water wetter also, it's supposed to keep temps down a few degrees over water and antifreeze alone.

Did you buy it locally? Jetting may present another adventure. Do you have a manual? This will really help when working on the bike and tuning the carb and suspension.



  • viggen

Posted July 13, 2005 - 10:30 PM


1st I just have to say this site ROCKS!!

Shell Rotella... I will check it out! I also use synthetic in my car's & change it 2500-4500 miles depending on which car & what I use it for, after a drivers school, the oil is only in there for a few hunder miles :applause:

Anyways, just wash the oilfilter, that's good to know! Keep it as a spare!

I have no clue what antifreez is in the bike, & I have always been told the MB coolant is the best stuff on the market. I am just still use to air cooled bikes & I forget it's got a radiator! I use water wetter from redline in my saab when I do drivers schools. Definantly helps keep temps down in the head, never thought of adding it to the motorcycle, hmmmm

Yes, bike was purchased locally from someone I know thus couldn't pass up the deal. He did give me a manual so hopefully that will help

I still do not have the starting routing worked out, probably spent 30 minutes kicking the dam thing today but it was worth it once it started :eek:

  • Lukejt

Posted July 14, 2005 - 04:03 AM


I still do not have the starting routing worked out, probably spent 30 minutes kicking the dam thing today but it was worth it once it started :applause:

I've worn holes in three different shoes, one were work boots trying to start my bike. Now that I've fixed the jetting, it's starting first or second kick. Hopefully I can keep it easy to start during the colder months (when I have the most trouble).

Oh yeah, I've got the 450 cam mod too. This is an awsome mod and will make the bike much easier to start. It also lets you bump start the bike.


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