Boxerworks.com

Everything's been going too well with my new hot rod. R90/6, 336 cam, Siebenrock power kit, Dellortos, etc. etc.
I've put about 270 miles on it. She's been running great with gobs and gobs of new found torque and power. Until the other day , when things got hot and I noticed she was running uneven and loosing power over 4200 rpm.
I pulled the valve covers, and as expected things had tightened up a bit during the initial break in. I also notice a little bit of ground up metal in the valve cover on left intake. That's not good. I cranked it over to check for oil delivery. All the rockers were pumping oil except for the left intake. Only a small amount is getting through. I'm sort of frustrated because I was meticulous at making sure the passage was clear and sealer was used sparingly. Looks like I'll need to remove the left cylinder and find out what happened. I'm guessing the o-ring somehow came out of position during installation and is blocking some how. The Siebenock kit uses the two small stud orings but does not use a cylinder o-ring. That part is sealed with sealer.
I removed the rocker to check for damage. The needle bearings looked OK and no significant ware was apparent other than a little sheen on the ends where they contact the blocks. I slid a thin wire down next to the stud but I couldn't seem to be able to unblock things. I'm guessing the metal I found is from the needle bearings so I will replace them. Should I be concerned about the valve guide?
At least oil pressure is nice and high and stable. If the main bearing had shifted both oil ways would have been blocked...right? The left exhaust side is pumping twice as much oil as both of the rockers on the right side.
http://bmwmotorcycletech.info/oilsketch.htm

I wonder if this would work. Install the rocker shaft upside down on the exhaust (which is pumping more than great). Remove the rocker from the clogged side and just install the blocks. Crank it over and see if I can blast out whatever is plugging the intake oil feed.

What colour was the metal you found Matt?
It's not the front bearing.
Oil to the left front means a blocked passage to me too.
I believe the oil gallery to the rear stud reduces in size from the larger gallery that supplies both studs.
It looks like the smaller gallery comes off the larger at 90 degrees, creating a likely trap.
What could it be? sealant, piece of cloth?

Regards blasting the gallery clear, would the inlet cam follower suffer any damage by not being spring loaded against the cam?
I think the excess pressure would be taken up by the relief valve?

Blasting backwards may be the way forwards. But.....that means bearing web off?

ME 109 wrote:What colour was the metal you found Matt?
It's not the front bearing.
Oil to the left front means a blocked passage to me too.
I believe the oil gallery to the rear stud reduces in size from the larger gallery that supplies both studs.
It looks like the smaller gallery comes off the larger at 90 degrees, creating a likely trap.
What could it be? sealant, piece of cloth?

Regards blasting the gallery clear, would the inlet cam follower suffer any damage by not being spring loaded against the cam?
I think the excess pressure would be taken up by the relief valve?

Blasting backwards may be the way forwards. But.....that means bearing web off?

The metal was silver and magnetic. I once drove my VW bus over 300 miles with a missing intake push rod with no damage.
The rod had broken at the tip in the middle of nowhere. I just removed it and kept on going on 3 cylinders. The cam follower will just move out of the way. I'm only planning on running the motor briefly to try and push the blockage out. If that doesn't work I'll need to pull the cylinder and fish in the hole with some wire. This is really pissing me off.

Are you sure that you did not put the rocker spindle in upside down? My R80 went from new York to Vermont before running the rocker bearing!

I would take off the offending cylinder, most likely to be the o ring or sealant. When it allback together again check oil flow withthe starter motor, top plugs off and grounded.

chasbmw wrote:Are you sure that you did not put the rocker spindle in upside down? My R80 went from new York to Vermont before running the rocker bearing!

I would take off the offending cylinder, most likely to be the o ring or sealant. When it allback together again check oil flow withthe starter motor, top plugs off and grounded.

Spindles were all correct. Anybody know where I can get rocker bearings cheap and fast? I've got a rally coming up soon.
If I did pinch an o-ring, is there a quick replacement I can get locally. Max BMW is great, but sometimes very slow and expensive. I'd hate to wait 10 days for a damn o-ring.

I'm with chasbmw, pull the cylinder and make sure.

Lots Of "O" rings are about some even the right size a trip to Harbor fright has a "O" ring kit you'd be suprized at how many become useful round the house

Top caps bottom washer seal on forks too! even can save a trip for household spigot "O" ring too!

Motorhead wrote:Lots Of "O" rings are about some even the right size a trip to Harbor fright has a "O" ring kit you'd be suprized at how many become useful round the house

Top caps bottom washer seal on forks too! even can save a trip for household spigot "O" ring too!

I think you need an o-ring that can resist constant submersion in oil as hot as 250F. Hard to say what you're getting at the hardware store.
I put my order in...It's going to cost me over $70.00 for two o-rings, a head gasket and two needle bearing. Let this be a lesson, always check oil flow at the rockers before riding. I was too confidant.
There used to be a great write up about changing needle bearings on rockers. Using a vice to push them in and out. Anybody have a link to that?

well I use them "O" rings myself in many many places..... motor, forks, where ever I can fit them some in my Motor and when I took my heads off the "O" rings are in good condition cheap to replace them 20 each size so I have lots


Buna rubber type

I stayed with the solid Bronze rocker bearings in mine LOL