Thoughts on what to replace when inside engine?

[Pierce1989]

Hello all, my '81 Honda ATC 200 has a head gasket leak in the back right corner. The trike runs fine, compression test wasn't too noticeably lower than specs, but the carbon buildup is noticeable where the leak is. So I was going to remove the engine from the frame to replace the head gasket. It'll be my first time, very excited to learn, and have the Clymer service manual. The question is that this machine is almost 40 years old... while I'm doing work in there should I just replace parts in the top-end and get it over with while it's on the workbench? Not trying to just throw money into it, but is it worth it to replace rings, valves, valve seals, valve guides, anything else (these are just some of the things I've read from posts on here)?? Or do you keep everything adjusted to specs, change the head gasket, and ride it until something goes wrong? I worry parts will be harder to find later in life, so this isn't only a technical question but need some advice on what you would do...

[oldskool83]

all the bearings and seal, if not having money and it runs fine as is, stay with top end and put in new oil.

[Gabriel]

Be mindful of the seals in the bottom end. If they're not damaged or leaking, don't touch them UNTIL you have a replacement. I am rebuilding a 200es motor and replaced everything i could possibly replace in the bottom end except the rod bearing. Finding those seals were a serious pain! No one offers a subtransmission gasket. Had to make those.

Even simple stuff like the shift shaft seal took a minute to scrounge up.

These 200cc motors are tough. I wouldn't do much in the bottom end unless it has leaks or strange noises.
DO however pull the side cover and thoroughly clean the centrifugal oil filter. NOBODY ever does this and I will bet my hat there's gummy thick crud in yours too.

Best of luck.

[Dirtcrasher]

Guys, I have in stock or can get just about any seal or bearing (in 2 days) from a lead I got as an industrial mechanic; He still helps me.

If I were to open an old motor, I would take off the clutch cover and clean the oil screen and oil filter rotor (if applicable), and if it were noisy at all, it may need a timing chain and the 2 tensioners/guides.

If it's super clean, clutch doesn't slip, and makes no noises, with maybe just a bit of smoke; I may not even open the bottom end...

It's a Honda, if the oil gets changed, they last decades.

But, once neglected, it's important to check the items I listed...

[Gabriel]

Guys, I have in stock or can get just about any seal or bearing (in 2 days) from a lead I got as an industrial mechanic; He still helps me.

Well great! Where were you when I was looking all over the place!!!??? :lol::lol::lol:


Mental note; Remember Dirtcrasher.

I have another one I am going to go all the way through in a few months. I will definitely hit you up.
Ever thought about getting a large ziplock bag, making a TRUE overhaul kit and keeping them for sale? Rebuild kits online are missing much. I'd be down for one for an '83 200E. It'll need everything but the piston and rings. I'll be having it bored and they will provide that.
The gasket seal kits online are always missing stuff. There's an oring on the flywheel bolt. Oil pump gasket and o rings too. The cam chain adjuster has an o ring. Others I can't think of off the top of my head. You never get this stuff.