Need advice on Top end/motor rebuild

[Hickersonbh]

I live in Los Angeles as well. What mechanic shop did you go to that quoted you all that stuff? I am looking for a mechanic in LA because I just bought my first r100.

[jackonz]

I have a 75 R90/6 with about 36k miles that needs to have some engine work done. I've had a local shop in LA take a look and has recommended a full rebuild of the motor.

What questions should I be asking to be shown that all of these need/should to be replaced?

I'm also trying to separate parts from top end rebuild and bottom end rebuild.

Anything I should consider doing as an upgrade? He has noted a 336cam, but everything I've read means there are additional items needed for it to work (dual plug heads, 40mm carbs, etc.)

Below is the work order and parts list:

1. Cylinder heads need to be rebuilt
2. Cylinders in spec, need minor hone on cylinder walls and new rings
3. Needs all new bearings, mains, and rods
4. Polish crank
5. Timing chain and sprockets
6. Full engine gasket kit

Parts list
ENGINE REBUILD GASKET KIT 11 00 1 255 023
HEAD Valve Guides
HEAD Valve Springs 11 34 1 263 873
HEAD VALVE JOB valve grind/seat angle - grind and dress valves-install new valve guides. ream to spec - blast and decarbonize ports. face heads
HEAD SPARK PLUG INSERT - ANTI corrosive insert included CAMSHAFT TIMING GEAR CRANK 11 21 1 250 198
CAMSHAFT TIMING CHAIN 11311250258B
CAMSHAFT TIMING GEAR CAM 11 31 1 250 253
CAMSHAFT TIMING CHAIN TENSIONER 11 21 1 265 455 CAMSHAFT TIMING CHAIN TENS SPRING 11 31 1 253 188 CRANKSHAFT GROOVED BALL BEARING 07 11 9 981 722 CRANKSHAFT BEARING SHELL 11 24 1 258 460 (set of 4) CRANKSHAFT BUSHING STANDARD 11 11 1 250 155 (set of 2)
RING SET - 2ND OVER -
11 25 1 259 855 SET: REPAIR KIT PISTON RINGS -
+1,00.10
CYLINDER HONE - clean up only. - machine shop.

Crankshaft Sprocket Duplex 1121198
Camshaft Sprocket Duplex w/tachdrive 1131253
Bearing Shell Conrod R2V 1124460
Conrod Screw R2V 1124553
Ball Bearing for Crankshaft, front 7711722
Duplex Timing Chain w/ Master Link 1131258
(Optional) Camshaft 336Degree 1131053

My question is what did you ask for? was the motor running and is it a case of as in mine just leaking or is it worn out, why is it in need of new rods and so on.

Did you ask for it to be hotted up or something?

[jackonz]

I purchased the bike used through a friend that has a shop, it was from a former client of his who bought it used off of craigslist. It was purchased with the intent to strip down and cafe it. They ran it a few times while it was sitting in their storage. It was smoking a bit and had a leak, so they diagnosed a top end problem. Since they don't normally work on BMW, they recommended another shop that does BMW builds for the motor work, he opened her up and came back with the following.

So there is a top end issue. Cylinders were measured. I need to see why they're going to a 2 over hone, wouldn't 1-over be first step after stock? I'm going to have to speak with him at length to go over what items are necessary, and what is optional.

If the bores are OK and you need new rings then all you need a de-glaze of the bores, as for leaks usual suspects would be pushrod tube seals, sump gasket and rear main seal. nothing that would come to the price you have been given.