YZF400 – prone to overheat?

[trooper8]

I’ve heard that the YZF400 tends to overheat if driven slowly. I’m in the market for one, but will be chasing my son on the PW50 a lot. Is this a known problem, or just a typical liquid cooled concern?

I'm in S. Cal.

[YZ400Court]

They did put a bit bigger radiators on the 426. My 400 will spew on nasty uphills even with the 1.8 rad cap (stock is 1.1), but not enough to worry about. My KTM 520 did the same thing. KTM offers a fan kit just for this problem.

[thumpsalad]

I have a 1999 YZ400 and the only time I had it overheat was in some very slow and technical rocky uphill climbs and even then it was only because I was jetted too lean, making the engine run a little hotter. I have re-jetted since then and haven't had one overheat-related problem. I also run straight distilled water. no corrosion problems and it runs cooler than anti-freeze/water mixture I have found.

I saw your other post on which bike to buy. Of course, we are all biased here ? , but honestly the YZF can do anything you want. Trails, MX, desert racing, whatever.

I would say the DRZ and XR are best for just trail riding. But try and open them up and they are pretty tame. Open up a YZF and HOLD ON!

Hope this helps.

[Ronski]

How about some info on the 1.8 Rad Cap? What bike is it off of?

[YZ400Court]

The rad cap is from a KX-500. I believe you could find one at any automotive hi performance shop that handles import parts. Also Pep Boys has them by Stant.

[ March 03, 2002: Message edited by: YZ400Court ]

[yz454]

Never had a problem with it and I have got a yz400 thats just over 450cc since 98, try running red line weter water.