Hello Gang, I am grateful for all the information on this site that helped with my engine overhaul and mods to the bike. Here is a story and write up about it: It all started last year(AUG 2021) when my buddy called me and said that his 2013 Terra is no longer running and I asked some questions... He was cruising down a road and it started to lose power and then died. After checking oil level(none left) and few other things it was obvious that it was seized. My friend is not mechanically inclined to tear into a project but I love a challenge, so I purchased it. After doing some research on here and getting all the manuals(Thanks a TON to whom ever posted them!!) I tore into my project. BTW my background: Aircraft Machinist(day job), Aerospace TIG welder, and locally known as "The motorcycle guy". I have a full machine shop in my home work shop. Well the ONLY thing that my buddy had done was get the ECU re-flashed. So 5100 miles of great Montana dirt road riding and ingesting all the dust made the piston rings disappear. Once I got the airbox off there was all the fine dust around the throttle body, that's when I knew the engine had to come out. When I got the cylinder off the connecting rod stood up on its own and tight to the flywheels. It took me a solid 4 hrs to get the stator to release off the crankshaft. I ended up building 2 pullers, the first one I didn't have a good thread depth so it pulled the threads. The second one I was more cautious cutting the threads on the lathe since the first one failed. MAPP gas wasn't hot enough so the oxy/acc torch had to come out to get the temp up to release the loctite. Once I got it off I was able to split the cases. When I got the flywheels out I noticed some abnormal wear on the cases where the side thrust washer run and the thrust washers were discolor from heat. It turned out when it was seizing the flywheels moved out of true and started to eat on the aluminum. In all everything wasn't in too bad of shape after inspection and cleaning, minus the rotating assembly. I wasn't going to drop $1100 for the flywheel set, so I shipped it off to CrankWorks for overhaul. They said "it may cross over to KTM or BMW sizes, not sure till we take it apart." In the 2 months it took them to get back to me I cleaned, inspected and measured everything. It really wasn't in too bad of shape a little wear on the cylinder but still in tolerance, rings were toast. I just hand lapped the valves, the intakes looked like they went thru a blast cabinet(ingesting dust). CrankWorks called and no luck, no parts available... not giving up... So back to the google machine for research, I found a speed shop in Germany that heavily modifies BMW 650's. After some emails with drawings for dimension translating it looked like it was a direct replacement but they didn't have a crank pin in stock. I just needed to see how bad my stuff really was. The connecting rod was good, rod bearing toast, and crank pin scorched. I took the crank pin it to work and rockwell hardness tested it(thinking I will build one) and it was HARD(60HRc). So I put it in the lathe and it polished right up and no score marks. Now I just needed a rod bearing.. After a couple hours cross referencing automotive rod bearings with no luck. I happened to look over to my manual shelf and seen a BMW R series 70-94 overhaul manual. I found one that was a match(ID/OD) but the width was a little short, still worth a shot. I had to grind the locators off the back side of the bearings to install in the rod. After installation everything spec'ed out and back off to the crank shop for reassembly. 7 weeks later and a couple phone calls to see how things are going.. still waiting.. 9th week done. Getting ready for re-assembly I needed the crank to set my side play distance. I fabricated some thrust washer shims to calculate the side clearance then tried to order the correct size thrust washers thru Husky. No luck with anything... Well lets just see how close is the BMW 650's stuff. Starting making a list of what I need(I will post again on this thread for part number cross references I used). Everything looks good off the description and pictures so I ordered the ones I needed plus 1 size smaller just in case. Everything in stock except the thrust washers, they had to come from Germany... 2 weeks later start putting it back together. 19th March 2022 - Its been 223 days since I tore the thing apart now its time for re-assembly. It took a couple tries with the transmission to make sure the shims where in the right place and it starting going back together. 2 days later it was ready for the frame. Putting the fuel tank back in was the hardest chore. After spilling oil everywhere trying to pre-oil it, I spilled coolant also. Don't forget the fuel, with that narrow/flat neck design I managed to spill that everywhere... BUT it was ready to Suck, Bang, Blow... and it did.. I have over 50 miles on it now and more to come. Thanks again for all the useful tidbits of information to the folks who posted and shared there experiences. I wanted to share mine. I will post my part number cross references that I used for my overhaul. E in MT
Great write-up and nice job on the fix! I had a similar fix on my engine where the Rod Bushing and Crank Pin were damaged. Couldn't get my hands on a replacement pin. I was in Teheran at the time. A metal working shop turned one from a "needle bearing" taken from a mega mining truck.
I'm curious how you dealt with the leaking air box for future fail-safe use in the dirt. I did the 3-D printed solution and going strong (and clean) for nearly 70,000k.
Engine O/H parts list and mods done to the bike: BMW PARTS LIST: Piston rings - 11 25 7 652 980 Head Gasket - 11 12 7 678 889 Cyl Base Gasket - 11 11 7 706 497/ 11 11 7 700 118 Thrust Washers - 11 21 7 652 932/933 Rod Bearing - 11 24 1 258 460(needs modification) Exhaust Gasket - 18 11 2 343 587 Water Pump Gasket - 11 51 7 652 950 Mods done: Pod Mod - seemed like the best filtration it is connected straight to the throttle body. Filter for Crankcase breather Heat Deflector Tape to underside of airbox EVAP can removed - filter on the fuel vent line ECU grounding strap This weekends(4/24/2022) Mod project: Swing Arm drain holes - Had to drill out one (SEIZED then broke) adjuster bolt and repaired thread with Time-Sert I'll keep this updated with any other future issues I may run into from the overhaul. E in MT
