Hello Inmates! Preamble Thought I’d start this thread to document the rebuild of my WR250R, and solicit thoughts from the very accomplished mechanics on this site. I’ve never torn into an engine before and look forward to the community’s input as I tackle this project. My current pictures are not great, but I will do a better job of documenting progress as I move forward. I hope that documenting my experiences can be helpful to those approaching similar problems in the future. Background I purchased this ‘08 WRR with 7,000 miles from a fellow inmate, with the understanding that it needed some engine work (having gone for a bit of a swim). The bike was running fine, but consuming oil. There was no smoke in the exhaust. Before I get into the pictures and details, I’d like to thank the folks who have put an amazing amount of WRR info on the web: Rick Ramsay, Highfive & Krabill, Basher Designs, and the numerous inmates with highly detailed engine rebuilds on this site. Meat & Potatoes The first diagnostic I performed was to run a leakdown test. I wasn’t looking for specific numbers, but rather wanted to pressurize the cylinder and attempt to identify any leaks. I could hear air escaping out the exhaust and from the crankcase (I removed the oil filler cap). Seems like the exhaust valves & piston rings are letting some air out. If the top end had seemed solid, I likely would have taken the engine to a pro given my inexperience and fear of splitting cases. However, having identified some easily addressable top-end issues, I decided dive in myself. Given that I lack a garage and enjoy the convenience of working indoors, pulling the engine seemed like the right choice. Here’s a picture of the engine in my "workshop": When covering engine openings, I’m a big fan of the used-nitrile-glove-over method in lieu of the paper-towel-stuffed-in approach. I’ll also point out that dropping the engine and lower frame as one unit makes an easy one man job (using ratchet straps to lower it all), and provides a built-in engine stand. I also took a look at the oil filter, and didn’t see any metal shavings or evidence of grenading engine, though I have no idea how long it’s been in there: Tore out a piece for a closer look: Enough of that. Let’s get started with the teardown. First step is removing the cylinder head cover: So far, so good: The factory workshop manual instructs to remove the cam chain tensioner at this point. I stupidly followed along, before having checked valve clearances. Since the engine was not at TDC and it’s hard to rotate without cam chain tension, I decided to keep going without getting baseline clearance numbers. Unbolted the cam cap, being careful to “break” torque from the bolts a little bit at a time, and in the reverse order from the tightening sequence marked on the part: Cam cap bolts are all the same length: What do we think of the bearing surfaces? Look fine to me: I realize that my pictures of the cams themselves are fairly blurry, but here they are: Cams looked completely smooth to me, with no visible wear or other issues. I proceeded to remove the cams, securing the timing chain to the uppermost bolt hole of the engine mounting frame. Again, helpful to have the frame here if you’re working on the engine outside of the bike. As you may be able to deduce, I cannot find my stash of zipties and had to improvise. Is a project without zipties destined to failure? Removing the cylinder head is straightforward, with 4 hex bolts and 2 Allen head bolts. All 6 fasteners have captive washers, so no need to worry about those falling into the crankcase. When removing the cylinder head, be mindful not to lose the 2 dowel pins visible in the photo. Also, make sure to take note of where the 1 longer hex bolt goes: Well, there she is. Let’s take a look at the piston: The carbon buildup on the right of the piston is actually several millimeters thick, as shown in this photo: Next step was pulling the cylinder itself. Very easy to do, with only 2 small bolts on the left side. No pictures of the removal, but here’s the bore: The first pic seems to show signs of “vertical scratches.” According to the service manual, the remedy is to “Rebore or replace the cylinder, and replace the piston and piston rings as a set.” The vertical scratches seem like evidence of the piston rings being exposed to contaminants or corrosion, which would explain the air passing through to the crankcase when I performed the leakdown test. It would be great to get the group’s thoughts on the cylinder bore. Having removed the cylinder, I took a look at the piston. The smudges on the piston skirt in 1st photo are just carbon from my finger: At this point, I took a break for some food. Chili-cheese fries and a double Spike’s burger – healthy perfection: Back at it. I removed the piston, which looked like this: And the wrist pin, which looked like this: The workshop manual says that for any “Blue discoloration/grooves” the remedy is to “Replace the piston pin and then check the lubrication system.” I can’t tell whether the two large matte areas I’m seeing are a design feature or a result of inadequate lubrication. Anybody know? The last thing I did today was take a look at the head. In order to determine whether valves are seating properly, the service manual suggested pouring solvent into the intake/exhaust and seeing whether any leaked through. I thought it sounded like a good idea: Intake valves were sealed up tight, but you can see some solvent coming past the exhaust valves. This would agree with the air heard escaping the muffler during the leakdown test. That concludes the day's progress. I have a number of questions where I would greatly appreciate the group’s input. Cylinder: I would actually prefer not to install a big-bore kit (to avoid the need for a tuner and the tradeoff in high RPM highway vibration). Assuming I try to stay stock, I have the following questions: o Does the cylinder appear to need repair/replacement? o If I opt to repair, what is the most cost-effective approach? A new Yammy cylinder is nearly $400. Not cheap! o Is it possible to just replace the insert? o In order to hone out the scratches, would we have to end up overbore? o If a repair means boring things out, can I buy oversize rings, or do I need a new piston? Cylinder head: o I plan to send this out to a motorcycle machine shop and have them do a standard cleanup, with no fancy headwork. Anybody have a good shop in the Boston, MA area? Piston wrist pin: o Do the matte-colored areas appear to be evidence of an oiling issue, or is that just how it's built? Next steps: o Should I pull the right-side crankcase cover and take a look at the oil pump screen? o Do we think it’s necessary to continue the teardown, split the cases, and replace bottom-end bearings? Thanks in advance!