Let me start by saying GREAT SITE. I have been reading posts on and off for years and have gained a lot of great info. This site is a great resource.
Been riding offroad bikes for 40 plus years now and have owned a lot of great bikes, never bought anything new - usually started with a "project" bike and rebuilt it. Usually put way more money in to the "project" bike than it was worth and then I would ride the hell out of it for a year or two and then sell it - at a loss of course. Some of my friends have really nice older bikes. : )
My latest project bike is a 2000 yz426. I Stripped it down to bare frame over the weekend. Dropped the frame off at the powder coater this am. hope to have it back Friday.
Have a set of forks off of a 2003 wr that I have already rebuilt -seals and oil - and will be installing on it. Picked up a 2005 yz450 Carb off e-bay and installed the aftemarket spring on the AC pump and the extended air/idle screw, replaced the diaphram etc. Going to go thru the rear suspension and linkage, new plastics, chain and sprockets, etc, etc. So a you can see I'm serious about really going thru the bike and getting it fixed up nice.
Finally to my questions. I rode the bike for about a hour before I retired it to the garage and started to pull it apart. Started easy, ran ok, no smoke, motor was a little noisy, idle wanted to hang, had a mild bog - not real bad. Anyways, tore the head and cyl. off the motor - Piston was a Prox. Measured the cyl for wear and taper - still within spec.
Lower rod bearing was in good shape, top rod/piston pin was trash! Great deal of galling between piston pin and rod.
1 Is this a common problem with these motors and if so is there any fix.
2 Should I go with a aftermarket rod kit and are they dependable --- and what brand should I use ---- or should I stay with oem = more money
3 Going to replace the piston, pin, etc. Good deals out there on aftermarket kits --- or should I stay oem again.
4 Thinking about reusing the main bearings if - after a good inspection they appear to be in good shape ---- or is this a mistake.
5 Head - Valves, Springs, Retainers, Keepers appear to be in good shape. Guides are tight. Was just going to replace the seals and touch up the seats and call it good --- or should I go ahead and replace some of these parts.
Don't mind spending some money to get things right but don't want to get carried away ether.
I appreciate any and all replys!