Topic: Maltboy's K5 Basket Case

[Maltboy]

I've been meaning to post some pics of my K5 project, but I'm usually too busy working on it! I figured I could post a few pics while sitting in the hospital with my wife as she recovers from spinal fusion surgery.

I bought the bike for $500. That included bronze swingarm bushings, carb kits, and a Craftsman motorcycle lift that it was strapped to because it was partially disassembled. It also came with a couple boxes of stuff that was removed by the PO. I figure I got about $300 worth of new parts, a $100 jack, and a $100 bike.

Here's a picture of the mess I made during disassembly.

[rocket johnny]

nice pile of parts !    hope your wife is doing well ,,

[Maltboy]

I decided to buy one of those zinc plating kits from Caswell to refinish the case bolts and other shiny stuff, but that meant I also needed to buy a parts tumbler to knock off the rust.  I found out that  straight muriatic acid will remove rust from bolts in about 10 minutes. I followed that up with a 24 hour polish in rouge coated walnut shells. After plating, I dipped the parts in blue (clear) chromate.  I must admit I was skeptical that I'd get good results, but the finished parts were stunning. So much so, that I decided to plate the carb bodies and all the steel linkage, springs, and anything else that used to be shiny. I polished the fuel bowls and the throttle  caps. I think the carbs turned out pretty good for a beginner.

[Maltboy]

She's doing well. They said she could go home today if she passed gas. I assured the doctor that this wouldn't be a problem. Fortunately I was out of smacking range.

[Maltboy]

As usual with these projects, there's always surprises. Some good, but mostly not good. I discovered two cracked main bolt bosses on the lower case, so I had to get a replacement. A couple of cylinder fins were also broken.

I ended up getting K3 replacements from a guy on eBay who goes by bobcovintageparts or something like that. I also got the head, just in case. All the parts were excellent, and his prices were good. The pistons and cylinders had minimal wear, especially compared to the originals. The ring end gaps were all about .010 after cleaning up the bores with the awesome ball hone I bought for the job. 

The case halves, head, and cylinders were masked to protect the innards and bead blasted on the outside. The head and case innards were soda blasted. Everything got power washed, including all oil passages.

The valves were soda blasted and lapped. All valve seats were smooth and well under the 2mm max. I was a little surprised that the valve springs were all about 2mm taller than the factory spec. I'm not complaining.

Everything got a coat of KBS engine aluminum. This stuff takes forever to cure. I ended up baking it at 200 for a couple of hours.

[Maltboy]

The crank was a good surprise. All the journals were smooth, and they measured in the middle of the factory spec for the original bearing colors. I went ahead and installed all new bearings.

The transmission was in fantastic shape. All teeth were perfect, and all the bearings were smooth as glass. Whew!  I was dreading the prospect of using my 20 ton press on transmission parts. I did have to drill out the 3 oiler screws and the shifter drum screw during disassembly. This may be par for the course, but what a PITA!

I decided to put as much of the innards as I could into the inverted upper case half, and then lower the bottom case onto it. The case halves went together perfectly with a little help from my son to guide the shifter fork into place. It was a relief to see a small bead of Honda Bond squeeze out around the case as everything torqued up.

The piston tops were soda blasted. I cleaned the ring grooves by hand with an old ring. Just for gits and shiggles I weighed the pistons and wrist pins. The pins all weighed exactly the same. The heaviest piston weighed 202.8 grams and the lightest was 201.0. I think that included the pin.  I took a Dremel to the deck ridges and got all of them to weigh the same. I hope I didn't screw up doing that.

The connecting rods and bolts were all within a gram, but I ground off a little of the casting flash on each side to get them exactly the same weight.

Installing the jugs over the pistons was definitely a learning experience. I tried using hose clamps, but I couldn't get everything to work right. I ended up tilting the block on the stand and using my fingers to push the rings into the chamfer on the end of the piston sleeves. Kudos to the guy who posted that tech tip. The rings are pretty easy to get started in that way. Once I figured that out, it only took a few minutes to get everything seated properly.

[BenelliSEI]

Nice work and great progress.

[Maltboy]

I started to install the head but I realized I only had 12 washers. So while I wait for those I figured I'd do some aluminum polishing.  Man, this takes a long time to get right.  The paint (or whatever it was) that Honda used to coat the covers hid a lot of grind marks.  Just when I thought I'd gotten all of them out with hand sanding (360 up to 1000 grit), I'd do a final polish and there'd still be scratches. I spent about 8 hours on the valve cover, and it was in pretty decent shape to begin with.  All those nooks and crannies are tough to get to.  I ended up polishing some of them with a Dremel tool. 

The other covers needed a bunch of sanding and buffing to get all the marks out as well. I read the threads about polishing, and I have a HF buffer and an old two-speed Baldor dentist's lathe with different wheels for each type of compound.  I do most of the polishing with the gray stuff and finish with the brown.  It seems like it takes way too much work to get the parts to look right. The parts look good when I'm done, but it seems like others on this forum get stuff done quicker.  I think I must be doing something wrong.

It seems a shame to do all this work just to have it corrode and look like crap in a year.  I have some KBS Diamond Clear Coat I could apply, but I'm afraid it'll haze.  I'm curious if anyone has used it on polished aluminum and how they liked it.