Honda Twins banner

1 - 5 of 5 Posts

·
Registered
Joined
·
1 Posts
Discussion Starter · #1 ·
Hi, I'm a newbie, and joined mostly to see if I could get a good answer to my problem!

I'm a good painter, and only a mediocre mechanic, okay? But I did have the sense to download the pdf manual. Now: a free CM400 came my way. (We all know, I trust, that "free" bikes end up being the most expensive bikes in your stable.) The engine (no kick start, and at the moment, no electrics either) will bump a little, one way then the other, if I take a wrench to the crankshaft, on the alternator side.

Took the clutch basket off, shaft spins freely, so, whew, the tranny ain't stuck. Most likely just really crusty piston rings, right? Okay. Took off the valve cover, and the rocker arm assemblies (cam chain is in the center.) Next, I'm s'posed to take off the cam gear -- but I can only get to the one bolt, on top! Even the ol' slimmed-down wrench trick won't allow me to remove the one now stuck on the bottom, because the engine won't turn.

The cam chain tensioner doesn't seem to be pressing against the chain, yet, there's not nearly enough "wiggle room" to coax the gear out from under the chain by tilting the cam.

Am I gonna have to cut the chain, just to continue with top-end work ... and then do the whole split-the-cases thing, just to put a cam chain back on?????:confused:
 

·
Registered
Joined
·
9,796 Posts
To make sure you have maximum slack in the cam chain, loosen the cam chain adjuster nut , pull up on the tensioner, then tighten the nut back up. You MAY have enough slack to 'walk' the chain around the sprocket.
 

·
Premium Member
Joined
·
24,208 Posts
I saw someplace recently that was selling a "master" link for the chain, if you can find that then cutting the chain should be ok. Don't know of anyone that's done this on these engines.
I don't think you'll get enough clearance to walk the chain off the gear, it's pretty snug in there.
Have you tried using ATF and acetone to try and dissolve any rust in the cylinders that's keeping it from turning over?
 

·
Registered
Joined
·
785 Posts
If its the type i think it is ( post a picture of the cam shaft and rockers ) you could remove the rocker arms which may help a bit.

Are any of the valves stuck ( large rocker to valve clearance ) open??

The above for freeing off the pistons in the bores, fill them with the mixture and leave for a few days, did the level of fluid drop??

Not sure how flammable the mixture may be but some "hot air" directed at the cylinders may help a bit.

You know of the problems with the 4 inner head bolts??
 

·
Registered
Joined
·
785 Posts
You got the clutch off then, and the rocker assemblies, so the 4 inner head bolts came out ok?

With a slack cam chain you should be able to either make the chain skip a tooth, a tooth at a time, or even derail the chain form the cam sprocket. You know about the upper cam chain adjust mechanism "anchor" bolt, the 10mm af bolt in the middle, on the head, at the rear.

However if the rocker assemblies are off ( the 2 whole castings with arms ) it is safe to turn the engine over with camshaft and chain still there and "in mesh", as long as all valves have closed.

Probably safer that way as then no real chance of cam chain "gathering" and jamming the crank etc..

Leave the outer head bolts in at least, with washers and or distance pieces, so cylinder barrel dies not "lift" ( for now !! ) whilst freeing off the pistons.

If head off then great, you can see any problem and lift the cylinder block free.

How is balance chain, broken??

How is flywheel, jamming because of rust??
 
1 - 5 of 5 Posts
Top