Hey everyone. I have been looking at a 2007 YFZ 450. I have read a lot of different websites and heard a lot of things about how much maintenance the YFZ 450 needs. One thing I have heard a ton about is some valves in the engine.

Does anyone know what type of maintenance this machine would need on a regular bases, what those valves are and what to do with them.

Also, are there any common problems with these quads?

All comments, opinions, and suggestions are helpful, thanks.

 

The valves are in the head, 5 titanium ones on the YFZ. Over time they wear into the valve seats and the become"tighter". You have to pull the head and use a feeler gauge to check tolerance, then replace a small shim that looks a lot like a watch battery with a different size shim. Eventually the seats, springs, and valves need to be replaced. Ti is great for performance at high revs, but spendy to replace. Also they have short skirted pistons that are light for quick revs but do allow a little more blow by. This style piston needs replacing more often and also causes more frequent oil changes due to contamination. Pretty much everything else on the machine rilar maintenanfeintemaintenance rvals to any other sport quad.

Regular maintenance is going to be oil changes and air filter cleaning/oiling. Chain maintenance, plus check and replace bearings and seals as necessary. Engine rebuilds are going to be a little more frequent depending on how hard you ride.

 

Thanks for commenting. How often would I have to adjust and how often would I have to replace the valves? Like every other month for checking the valves and like every year for replacing them?

All comments help

 

It is more an hour thing and depends on how hard you ride. Valves I would check every 10 hours or so. top ends I have heard guys putting 50 or 100 hours on and being good. The thing is if you destroy a piston it can easily be upward of 2k to fix the damage so I think 100 hours is pretty crazy. The factory has specs but I feel you can extend rebuilds out if you don't race and bounce off the rev limiter all the time. Valves need to be redone when you start running out of thin shims to keep it in spec, lol.