Thread: common 'wear items' in engine

its a good idea to ditch the 5000 mile valve springs with dr atv wide coil H-D springs,their pretty cheap insurance for the long haul.

Originally Posted by P.C.

its a good idea to ditch the 5000 mile valve springs with dr atv wide coil H-D springs,their pretty cheap insurance for the long haul.

That's a good one, had not thought of that. Sound like a def. "no" on the bearing cam and thumbs up on the SL cam though.

Originally Posted by Squeebles

I am in the midpoint of a 3-speed motor rebuild, had about 5k on the speedo when disassembled. I have it apart, it is apparent it will get a cylinder honing, new piston and rings, points, condenser and cam assembly.

My question is this: What are the typical wear items or weak spots in the internals? I plan on replacing all of the above along with clutch plates. For you rebuilders with lots of experience, are there any other things that should be replaced while I am in there (even if they look good on inspection?) I am thinking of historical weak points in the engine etc. For example, the oil spinner looks fine, should it be replaced anyway? Any tips appreciated, thanks!

The most common items, in no particular order. Not all will be need replacing. Some are just cheap insurance. There may be other, less-frequently worn-out, parts not on this list.

• cam chain, roller, idler & oil pump drive sprocket
• rubber tip on the cam chain tensioner piston
• clutch discs
• clutch plates (not usually worn out)
• shift forks (also check the contact surfaces on the gears, burned forks can also mean metal residue left behind)
• valves, the intake will usually be "tuliped" & leaking
• oil pump (worn teeth on the drive sprocket indicate pump bind)
• throwout bearing
• valve seals
• piston & rings
• cylinder...can range from stock diameter, needing only deglazing, to worn/tapered/rusted/scored badly enough to require a 2-size overbore
• points & condensor
• case screws (rarely ever worth reusing)
• C-clips, definitely not worth reusing

Thanks to all so far for the info, and racerx for the excellent list. Lots of things I had not thought of, definitely glad I asked. Hopefully this will be a thread that many will use in the future, I think others probably have had this question.