Topic: mattcb350f's........CB350F Project/Restoration (DONE)

[HondanutRider]

Hey Matt,

Good luck with the new job and I hope you enjoy it.

BTW, I had noticed the same little oil weep on my CB350F after I got it running.  It wasn't much, but on the left side there was always some film that would get blown down the engine casing after a run.  It wasn't much but I could always wipe some away.  Then, after a few outings it's stopped!  No more oil is coming out and the cases are staying clean.  I figure that the seals just needed to get hot and wet a few times, to expand and seal themselves.  At any rate, the little bike is very well behaved and properly dry.

(This post also PM'd to Matt, but I thought the info on the leak might be generally interesting.)

[mattcb350f]

Hi all,

Haven't been around much with work/marriage/baby on the way...

But I finally decided to fix the pesky head gasket leak. I took the head off yesterday and found that the gasket didn't seal well at all (especially where it was leaking  ). Not sure why, other than it wasn't a Honda gasket. I'm going to try member 'TTR400's fix to the leaky gasket issue on the 350/400F which I hope does the trick; which basically involves siliconing around the OUTSIDE of the rubber dowel seals and orifice valve seals between the seals and the head gasket as added insurance, and spraying the gasket with copper sealant before installation, then torquing the head to 18 ft/lbs.

However, I found a little problem which I have to address first. I found one of the exhaust valve guides has spun a little. The only way I could tell is because its been ported, and the guide has an uneven shape at the bottom.

My machinist hasn't gone to work on it but hopefully it can be repaired.

One other point: I also noticed that the cam chain has started rubbing the U shaped adjuster part under the crank, indicating that my cam chain was too slack. Luckily, it's not damaged so it still works fine, but a lesson to me that the natural Honda way of adjusting the cam chain doesn't cut it and I'll have to make sure it's a little tighter after I get the ole gal back together.

 Cheers, Matt.

[HondanutRider]

Hi Matt!

Congrats on the lifestyle change.  That's nice to hear.

Yes, those oil leaks are a nuisance and I've recently posted some further experiences of my own.

On the cam chain adjusting front:  I got a good tip/idea from fasturd who replaced the threaded plug on top of the adjuster rod with a stainless hex-headed bolt, and then added a nut to lock it in place.  The idea is to use this bolt to tighten down (not too much though ) the adjuster rod after loosening its lock-bolt, instead of relying on the spring on this rod to automatically find the correct tension.  With the engine running at idle, you can slowly apply more tension until the chain noise quietens and then back it off a bit before locking everything in place.  The end of the stainless bolt should likely be rounded smooth to make better/easier contact with the end of the adjusting shaft.

This technique is much better than trying to jam a screwdriver into the hole while tensioning-up the mechanism.

[mattcb350f]

So I got the engine back together last week, and so far no leaks  The new valve guide was larger than the one that came loose so hopefully it will stay put.

I'v decided to stick with the ole' screwdriver trick for adjusting the chain, which seems to work for me. As far as what's next for the little rocket... just some fine tuning.

I have a set of 78 mains to go in the carbs when my gaskets arrive. I'm happy enough with the way it runs but it has some hesitation between 5-8k rpm which i betting is a lean condition. Really hard to tell though, but I should no when I go up a size (running 75's now)

 Matt.