Topic: Someone removed the cam chain tensioner on this CB350Four

[fourintofour]

I got this CB350 FOUR for free from a sailor. It was partially disassembled when I got it. It looks like the previous owner did some unusual things to engine. I'm trying to get it back to as stock as possible.

I'm putting the cylinder head back together with new pistons and sleeves, but it looks like there is no cam chain tensioner adjustment. In fact, the slot has been filled with some kind epoxy or glue. This doesn't seem like a good idea? I thought that would be a necessary part to have. I feel like I'm in a little over my head now and not sure how to proceed. The front (exhaust side) rubber tensioner was kind of wedged into the chain and was very difficult to remove. It was also snapped on the top. I'll definitely have to order a replacement but I'm not sure how that piece fits back in there.

Of course, being a 350F there are very few resources available! I have the Clymers and it's real sparse.

Pics attached.

[wolf550]

doing some work on a couple 350f engines and one had a bolt with a tiny pin at the end and the other was just a bolt. both had a nut on it i guess to lock into place. not sure which is correct but i would think that parts should not be discarded or left out.

[fourintofour]

Agreed, but I'm not sure how to proceed. For some reason, the price for a cam chain assembly is looking like it could be in the hundreds of dollars. Check this out:
https://www.cmsnl.com/honda-cb350f-four-1972-usa_model435/partslist/E++05.html

 I'm not sure whether I should buy another motor for the same price and start over or if there is some way to continue with this one.

[wolf550]

theres some good vids of 350f engines being put back together on youtube. i think one is woodys and there is a british or english guy who goes through the processess. im not sure if the cases have to be split for these engine to put that u shape piece in there but Ill be checking on it also.

[wolf550]

sorry it was dewoodys shop

if it is the u shape piece it shows him putting it in with cases split at end of vid.

if it is the long bow shape piece that might just go in without the cases split.

[bryanj]

There is a firm in UK making a stainless repair kit for the cam tensioner locking bolt and casing thread, there is then the rubber tipped pluger with dual springs that push on the "horseshoe" to bow the back blade against the chain.
The DS and CMSNL assembly is a modern alloy cnc machined part from a UK member living in South Africa. Original ones are normally knackered by the chain hitting the pivot are and burring the pivot so its tight.
I may be able to get a very good used one but that would be about £50gbp plus postage to us, its a rare and obsoleted part now

[Bodi]

it's an odd bolt. It looks like an 8mm bolt but is actually 6mm where it tightens in the case. You use 8mm torque and it snaps off down in a hole. The 8mm thread is just for the locking nut.
If you can get the 6mm stub out and can't find a NLA OEM bolt, a 6mm bolt, washer, and nut works OK.
Removing the stub is rarely easy.
The bolt above it blocks off the hole for the pusher rod but that's captured... it won't come out that way.
And the springs that do the auto tensioning have lost springiness over the decades so help is needed.
If you have the lock bolt you can remove the cap bolt and push down on the rod until the chain quotes and lock the rod. Engine running of course with the hot headers right beside it all.
If not you can put a longer bolt with lock nut in the top hole to contact the rod and screw it down until quiet then lock it. You need to loosen or remove the lock bolt stub first.
Overtensioning the chain will eat away at the slides so only use enough force to just quiet the chain It should rattle slightly.

[fourintofour]

Well, I thought I was at the rebuild phase of this project, but it looks like it's time to split the case.