Airhead Timing Chain - Who's done it?

[Rapid Dog]

...,yeah, that's what I was thinking too...?

[wirewrkr]

Originally Posted by Rucksta

Stagehand I appeciate what you're saying about scope creep but...
can you pull the rockers, remove the pushrods and insert a telescopic magnetic wand down each hole to retract the cam followers then remove the cam without further upset to the top end?

I haven't tried it so it's more of an idea that an actual techinque.

Yes, that works.
Done it.

[Stagehand]

good idea!

[Rob Farmer]

all you need to do is turn the cam once it will then push the followers up out of the way or drop the sump and do it with your fingers.

[Rapid Dog]

...now you guys got me thinkin' again.
I just didn't want to undo my nice sealed jugs.

Drop the sump? I don't see any access to the lifters in there...

[Rob Farmer]

Originally Posted by Rapid Dog

.
Drop the sump? I don't see any access to the lifters in there...

Well that's egg on my face..could have sworn you could get to them from below.

I've swapped cams without taking the jugs off before. With the pushrods out just turn the cam and the lifters will be pushed up out of the way.

[Lornce]

Originally Posted by Rucksta

Stagehand I appeciate what you're saying about scope creep but...
can you pull the rockers, remove the pushrods and insert a telescopic magnetic wand down each hole to retract the cam followers then remove the cam without further upset to the top end?

I haven't tried it so it's more of an idea that an actual techinque.

Sounds doable to me.

[Bill Harris]

Originally Posted by Rucksta

...can you pull the rockers, remove the pushrods and insert a telescopic magnetic wand down each hole to retract the cam followers then remove the cam without further upset to the top end?

I haven't tried it so it's more of an idea that an actual techinque.

I 've not done that because I've heard that the magnetic wand can magnetize the followers and make them attract every magnetic chip in the oil flow. I've not seen it one way or the other, just sayin'...

[wmax351]

Originally Posted by supershaft

Cam sprocket? That all depends on if you have a duplex or simplex chain. The simplex cam sprockets for some reason almost never wear AT ALL. Your chain will last just as long with a used one because their is no difference usually between a used one and a new one. I am going on my experience as a pro wrench AND the accumulated experience of all the mechanics that I have worked with at a number of very busy dealerships. Not to mention what I gleaned as a child and young adult hanging out, helping, and working in my dad's BMW dealership.

It doesn't take any special tools other than some feeler gauges to set the camshaft end play.

Yeah. This was for a /5 with the duplex.

[supershaft]

Yea, the duplex cam sprockets wear. They often need replacing if you want your chain to last anywhere near as long as it should. The crank sprocket just about always does.

The lifters won't hit you in the face after you take the sump off but you can get to them from there.

The problem in my view with replacing the cam without removing the cylinders is that you can't check the condition of the lifters which very often is not good. There is no way I would run a sport cam without first checking the lifters for pitting.

[tony the tiger]

Originally Posted by BMWRSNUT

Snowbum has a bit to say on this & also suggests consideration as to whether the tebnsioner & spockets are changed.

...

Changed both gears and the chain on my sidecar rig (formerly Snowbum's). Followed the directions on his webpage - it was pretty simple. Scary as to some details, but a borrowed "caged" 3-jaw puller and a thrift store electric frypan (to heat up the gears and bearing, suspended in an oil bath)... used a brass washer during install between my drift and the crank gear & bearing. Can't remember the temperature but they really slid right on very easily. Don't forget to replace the bearing!

Just finished doing rings/heads on the rig too - the old Airhead has a noticeably improved performance with ~104,000 miles on the clock (purchased @92k).

Oh yes, and that frigkin master link...

[Xcuvator]

Most of the BMW lifters I have seen that have some miles on them are starting to show at least the first signs of pitting. FWIW I think a new cam should have new lifters.
also:
If you put a dab of sticky grease on the end of a pushrod the lifter can be withdrawn.

[supershaft]

From what I can tell, I think a lifter that is in your bike and not pitting has just as good or better chance of not pitting in the future versus a new one.

[Hawk Medicine]

Originally Posted by Xcuvator

Most of the BMW lifters I have seen that have some miles on them are starting to show at least the first signs of pitting. FWIW I think a new cam should have new lifters.
also:
If you put a dab of sticky grease on the end of a pushrod the lifter can be withdrawn.

How many miles and under what conditions? I've seen under 40K mile lifters that were pitted to Hell from the bike sitting a lot and the ones that came out of my 200K mile R90 were just starting to go bad. It just depends and thats why, if I was going to swap cams, I'd at least want to take a look.

OTOH, the word on the street for the last um-teen years says that if you're installing a new flat-tappet cam, you install new lifters. Always...

[Rapid Dog]

....I'll do the cam some day when I'm sure I've replaced everything else. I've only done about 70% so far...