Looking for a little insight on an M18 (again)

[jimbob200521]

Long story short, I bought an 1811 with a (turns out to be) more or less bad motor. So I looked around and found another used M18. It starts right up and "sounds" better than the previous one, however I want to do a little preventative maintenance on it before I throw it into the heat of this coming summer.

What I'm going to do is remove the heads, clean them up, and put new gaskets on them. What I'd LIKE to do is lap the valves and make sure they're getting a good seat. The process sounded intimidating until I did a bit of looking up on it and found this guide (I know it's not for a Kohler but the principal should be the same):

http://www.myhonda650.com/cb650lapping.htm

So that leaves me with a few questions:

Is this a good procedure to follow?

Should I replace the valve springs or anything else while I'm in there?

I've read about grinding the valve stems, is this something I'd need to do or even worry about?

Any other advice/suggestions? I've got the old M18 sitting around I can use as a "practice" motor before I get into my good M18 so I won't be going into it totally blind. Thanks in advance guys!

[Sam Mac]

If you have not downloaded the M18 service manual here is the link for it.

http://www.onlycubcadets.net/forum/s...ead.php?t=4648

[jimbob200521]

Originally Posted by Sam Mac

If you have not downloaded the M18 service manual here is the link for it.

http://www.onlycubcadets.net/forum/s...ead.php?t=4648

Thanks for the link Sam, that was one of the first things I went through. Unless I missed something, they say to lap but don't say how to really. I just wanted to make sure the method I found was going to work fine

[Sam Mac]

Not sure you need to lap valves unless you are doing a valve job.

[jimbob200521]

Originally Posted by Sam Mac

Not sure you need to lap valves unless you are doing a valve job.

I won't know untill I open it up but I'm wondering if there's some buildup or something around one or both of the intake valves. It's only happened once and doesn't hickup when running, but I had a backfire through my carb one time which makes me curious. Could have been a fluke or something, the motor sat for about a year before I got it. When I pulled one of the spark plugs before I ran it for the first time, it had some buildup around the electrode so I replaced them both. Since then, they've been coming out clean but that makes me wonder if there's anything inside that needs cleaned (I know there is, it's probably never been de-carboned).

[Sam Mac]

Well if it's running OK about all I would do is to pop the heads off, clean them up and put a new set of head gaskets on it and leave it alone. Since you have one that needs rebuilding I would overhaul that one then you have a spare if this one pops.

[mickb72]

Hello, i think there was a service bulletin about pinning the camshaft pin. It slides out of the block dropping the governor. K-boom i think thats why a lot of them blew up. Do the kt 17s have the same problem? Mike

[J-Mech]

Originally Posted by mickb72

Hello, i think there was a service bulletin about pinning the camshaft pin. It slides out of the block dropping the governor. K-boom i think thats why a lot of them blew up. Do the kt 17s have the same problem? Mike

Don't go there...... that requires COMPLETE dis-assembly. Don't make him worry.

Ryan, I'm with Mac. No need to lap, unless your doing a valve job. Pull the heads, clean everything up. May even pull the valves and clean them. If you see a sealing issue, do a valve job. Worrying about your engine won't make it last longer, or blow sooner. Take care of it, it will last as long as it's gonna last.

[jimbob200521]

Originally Posted by J-Mech

Don't go there...... that requires COMPLETE dis-assembly. Don't make him worry.

Worrying about your engine won't make it last longer, or blow sooner.

Hey give me more credit than that, I'm not THAT paranoid

I know/knew about the governor and honestly, it hadn't worried me. One of those things that out of my control.

Originally Posted by J-Mech

Ryan, I'm with Mac. No need to lap, unless your doing a valve job. Pull the heads, clean everything up. May even pull the valves and clean them. If you see a sealing issue, do a valve job. Worrying about your engine won't make it last longer, or blow sooner. Take care of it, it will last as long as it's gonna last.

Ok, I'll heed Sam's and your advice; I won't mess with lapping the valves unless I see an obvious issue.

As far as pulling them out to clean them, if I end up doing that, do I need to set/reset any valve tolerances?

[J-Mech]

Originally Posted by jimbob200521

As far as pulling them out to clean them, if I end up doing that, do I need to set/reset any valve tolerances?

Check it, but unless you face the valve stem, it isn't adjustable. As I recall, the spec is pretty broad.