Boxerworks.com

Well my last post was about condition monitoring the timing chain. I've since decided to go ahead and change it. Reasons:
1. Consensus amongst a lot of folks was that it would be needed soon anyway.
2. On my way back from Pontiac on the 11th I sensed a new sound kind of like a Honda timing chain from the old 305s when running at slower speeds, around 60...but no slapping noise.
3. I originally said no jumping timing under strobe - that was based on the last timing check in April. I now see double image at about 1/16" on the advanced side and 1/16" on the retard side at the same flash of the gun.

Never did this job om a BMW but after checking Snowbum's site, doesn't look too difficult.

I'll be ripping into it this weekend so any words of caution, advice on getting the sprocket back in (I'll be using heat on the sprocket and dry ice on the crank stub ), etc always welcomed. The all-in-one tool from Cycleworks looks good but I think I can do it without the $140 tool.

I'll let you know what I found after its apart.

Good luck, Ray. I'll be listening to how your sprocket plans work out.

I'm ordering a new crank sprocket but if I need a cam sprocket too I'm gonna get drunk

Ray from Indiana wrote:I'm ordering a new crank sprocket but if I need a cam sprocket too I'm gonna get drunk

It's a doable job. Just sober up before trying to install the sprocket.

Chuey

Your double image isn't likely the chain if it is stable. A timing chain will make things bounce around quite a bit.

Good luck and ask before picking up the hammer.

Chuey wrote:It's a doable job. Just sober up before trying to install the sprocket. Chuey

Chuey's right, it ain't sprocket science.
Take your time, take photos.

I put the sprocket in a hot oven for a while and wrapped a freezer pack around the crank stub.
A couple of taps with a plastic hammer was all it took.
Be ready and be quick.

Duane Ausherman wrote:Your double image isn't likely the chain if it is stable. A timing chain will make things bounce around quite a bit.

Duane

I'm all ears...even if they are cauliflower type. What are the other reasons for dual images besides a stretched chain?

Thanks

Ray

Ray from Indiana wrote: Duane

I'm all ears...even if they are cauliflower type. What are the other reasons for dual images besides a stretched chain?

The nose of the cam shaft on the pre bean can ignitions is relatively vulnerable. If it gets knocked hard enough it can get bent. Since each 180 degree revolution of the camshaft triggers an ignition event, a bent camshaft nose can and does generate a double image. If the cam chain is good the double image will be stable, In effect you have two one cylinder engines, joined at the crank, each cylinder with a different ignition timing.


Ken

Thanks Ken but as I said earlier this a "bean can " w/o points bike, an 82 R100