Do I need a new cam chain?

[lgordnier]

So, i'm rebuilding the top end on my 200E. Rode it around for a while when I purchased it, found out the cam is pretty much gone... and I've been wrenching since!
New cam, new rings on the way, reseated the valves, new valve seals and gaskets all around. But here's my question....
I got a new cam chain, just to have one. I hear they make quite a bit of noise when they start going bad. But this one hasn't made any noise, far as I can tell. Should I just take the extra time to pop off the flywheel, and change the timing/cam chain anyway?? What do you experts think? I'm expecting everyone to say 'just change it bro'

[Jason125m]

I would highly recommend changing it. You will have peace of mind for the next 30 years.

[90guy]

I second to change it. You have it take the time to change it and you will be at peace with it. You are already putting plenty of new parts in why stop short and end up having the chain skip and wreck everything you just did? Just my 2 cents.

[kb0nly]

Yeah do the chain now. You will regret buying all those gaskets again later if you don't... LOL

[yaegerb]

Change it while you have it torn down.

[CodyRosa]

'just change it bro' =)

[trike savior]

looks like you have your answer already but yes X 6. they don't always make noise when needing changed. it can still be at end of adjustment and not make noise. so yes change it and check the chain guides for wear as well.

[Badbmwbrad]

A worn out cam? Why does this happen? My theory is the engine oil used was incorrect for the application.

Small, air-cooled, 4-stroke engines having flat tappets need engine oil carrying API-SG specification. It has sufficient ZDDP anti-wear additive to reduce potentialfor metal-to-metal contact at sliding surfaces (cam lobe-to-tappet interface).

Use of automobile engine oil is said to be incorrect as it no longer has ZDDP in order to prevent coating of the catalyst.

[barnett468]

Hello


"just change it bro'"

I guess ya didn't need to ask, lol. however here's somethin new. Check the chain guides also, replace if worn.

[shovelryder]

A worn out cam? Why does this happen? My theory is the engine oil used was incorrect for the application.

Small, air-cooled, 4-stroke engines having flat tappets need engine oil carrying API-SG specification. It has sufficient ZDDP anti-wear additive to reduce potentialfor metal-to-metal contact at sliding surfaces (cam lobe-to-tappet interface).

Use of automobile engine oil is said to be incorrect as it no longer has ZDDP in order to prevent coating of the catalyst.

Engine oil now,all brands, are ten fold better than when these things were built.........The machines how old????? Thats why its worn the cam out....Just use! Lol....I still see folks changing bike oil every 3k, and cars at 3500......This is unreal. No issue at all to go 7k between changes.......I like servicing my friends toys though......Cause he runs great oil and changes often.....so I always have free clean oil around!

[barnett468]

Hello

Forgot to mention, you can not run old rocker arms on a new cam they will cause premature cam failure and the rocker arms can not be resurfaced. If you run new rings on a used bore they may not seal, you need to check for wear.

Now the bad part. I'm pretty sure your 30 year old bore is worn out if it hasn't recently been done.Some people will simply tell you to just "deglaze” it and it will be fine. It will not. Yes it will run, yes the rings will never seal because your bore is not "true" yes it will have lower than optimal compression and probably smoke due to the worn bore. You must measure taper and concentricity in two radial positions on both top and bottom of cylinder to determine amount of wear. Any concentric wear in excess of around .001 is too much. Any taper in excess of around .015 is too much. You also need to measure piston to cylinder clearance, anything in excess of around .005" is too much. Hello again


The most cylinder wear will be approximately 1/2" from the top in a position that runs "front to back" not "side to side" since this is the direction the piston "rocks" at the top of the stroke and the least wear will be at the bottom in a position measured from "side to side" not "front to back" since the piston never touches here.


If it is just slightly worn you can have it trued but this will increase the size to a point where your piston to cylinder clearance will be too big.

I personally would prefer to do it once now that it is apart and not do it again in a week.


Hope this info helps

[barnett468]

I meant "if it hasn't recently been re-bored", sorry i have no edit button.