Firerunner's 81/71/72 bobber build

I am starting a new thread after picking up my victim today. She is a 81 XS that has been poorly partially chopped by the previous owner. She smokes. She backfires. She would probably cuss a little bit if she knew how. I'm going to have to watch her for a while to make sure she doesn't have a drug problem.

Here she is at the PO's house.

And here is a video of her running when I got her home.


She came with a couple of extra frames, a couple of extra engine blocks (apart), several extra sets of forks and triples, about a half dozen wheels, and an odd assortment of Yamaha, Triumph, BSA, and Norton parts. For $350, I'm happy.

The plan is to get a frame legal and in my name, then hardtail it with a TC Bro's tail, clean it up a bit, replace the TCI with points (no magic box, simple parts I can fix), and ride it. The long term plans will include fenders, a permanent magnet charging system, and an upgraded ignition. If I somehow get some money, I will also consider a rebuild and rephase. I am all about simple. All I need is a headlight, taillight and brake light. I will probably end up using the front wheels from the 71 and 72 baskets that came with the bike as my front and rear wheels, and going for a skinny, lane-splitter look.

After a trip to DMV, and ordering a TC Bros hardtail, the total build cost is $700.00. (120 at DMV and 220 for the hardtail). I need to sell some of these parts. The 81 is registered, so for now I will leave the front end alone completely. I still think I can finish this for under a grand, especially if I can sell the rest of this stuff. It wont' be anything extravagant or groundbreaking, but it should be a fun little runner.

Well, I actually rode it today. Finally. Sure, the battery was held on with electrical tape, the springer seat was held on solely by the weight of my butt, and the wiring harness was basically a creatively wired spiderweb located between the air cleanerless carbs and the fenderless rear tire. I rode almost exactly a quarter of a mile before running out of gas in front of my house. It was enough. A very long week was made better by a ridiculous spin around the block on a loud, smokey, ugly caricature of a motorcycle. I think I'll do it again tomorrow. I may get lucky and have enough time to actually hardtail it this weekend.

I bled the brakes, tightened everything I could access, and corrected the tire air pressure today. I also fabbed up a temporary kickstand, though I still need a spring. I've tightened it down sufficiently that it doesn't drag around left hand turns anymore. I also attached the factory seat (which the previous owner had cut short and covered in camouflage fabric) as a temporary measure.

Having given the bike enough attention that I felt it was unlikely that it would spontaneously combust or deconstruct into a pile of bolts and old parts, I actually gave it a bit of a ride. Holy crud, I've missed being on a bike! It badly needs some tuning, but it still rides along quite satisfactorily. I suppose the current lack of air cleaner or muffler has a great effect on the mixture. I got new plugs for it. I'll install them tomorrow and see if that doesn't help the idle any. Currently, it will not idle unless it is at half choke. I imagine that a thorough cleaning won't hurt anything, and that rejetting to acommodate free flowing air cleaners and open pipes will certainly be in order down the road.

Well, the back of the bike fell off.

I used an aircraft engine hoist to lift the bike onto a rolling work table and strapped it down.


The I chopped it. Let me tell you this- the angle grinder is not the optimal tool for this job. I screwed around with it for a while, and managed to cut the tube in most of the right places, but it took forever. I then pulled out the sawzall and found that I should have started there. It made quick work of my task.

The TC Bros hardtail went on great, and I got it mostly finish welded. I am going to pull the carbs on Monday so that I can weld the bottoms of the top tubes. Once that is done, then I just have to figure out footpegs, rear brakes, rear tank mount, and seat mounting.

I didn't get as much done today as I would have liked. I did finish the hardtail welds, and got started with the rear brakes. I played with some different tank options, but ultimately decided that I was going to have to make the stocker work for now. I just have to cut off the stock rear mounting tab and weld on a stud, then drill and sleeve the backbone for the stud. I ran water through the tank for a while, and then emptied it. I'm going to let it sit in the sun and dry for a while before I even consider putting fire to it.

I also started designing my seat hinge. The smallest tubing I have has an ID of about 1/2", so I suppose I will use that and a 1/2" bolt.

My plan is to run my pegs "mulligan style".

I still need to figure out how I'm going to run the rear drum brake reaction bar. I would like to make it as low profile as possible without sacrificing any structural integrity. I was considering making it out of 1"x 3/16" bar. Think that would be strong enough? That is the element that needs the most additional planning.

Nice work. Moving fast.

Hey, look at that! There is someone reading all this tomfoolery!

I fabbed up my rear brake stay and reaction bar, and my rear brake activation rod today.

I am retaining the factory rear brakes. For the rear brake stay and reaction bar, I used 1/4"x 1" bar, and drilled a 1/2" hole in the brake end. I then opened up the hole in the tab on the brake plate to 1/2". A grade 8 1/2" x 2" bolt fit in nicely, with just a little bit of fitting on one flat of the bolt head. This made the bolt fit snugly into the factory parts. I then used a break to make a dogleg in the reaction bar. I fabbed up two tabs with 3/8" holes in them, and used an Allen head 3/8" capscrew with an interference nut to sandwich the other end of my reaction bar.

With that all welded in, I moved on to the brake activation rod. I don't have access to a lathe, or I would have turned the end of my stock down and threaded it for the 5mm x .8 stock brake adjuster nut. As I was unable to do this, I had to cut the ends off the stock rod and weld them to a new piece of rod. I'm happy with the results:

When I bought the bike, I noticed that the head gasket was weeping oil consistently around its perimeter. After noticing this thread: http://www.xs650.com/forum/showthread.php?t=2034&highlight=head+torque+spec, I'm hopeful that I can solve it by re-torquing. The transmission was recently installed, so I wouldn't be surprised if everything was a bit loose.

Great progress. You mentioned an aircraft hoist?

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Yeah. A small one. Picture an engine hoist that doubled in size. It needs some work (new hydraulic ram, wheels), but can be tipped back 90 degrees and towed as a trailer. It is used for lifting engines into small aircraft. I don't think I have a picture of it, but I can try to remember to snap one later.

I made some progress today. The tank and seat are mounted.


I got the bike back on the ground and found out that I misjudged the necessary placement of the brake pedal. I will have to redo the brake pedal pivot point and brake rod. I'm thinking of moving the brake pivot point under the frame rather than over it. That will place the brake pedal closer to where it was designed to be in relation to the peg, which I think I will run right off the exhaust bracket. I have a couple of foldable passenger pegs that thread directly into the exhaust bracket. They need to be rebuilt, but the mounting sides are fine.

Here she is on the ground:

So, the to do list is getting shorter-
Rear brakes
Pegs
Build new shifter and brake pedal
Build battery / TCI box
Rewire
Paint
Retorque head bolts.

Edited to add: Here is the wiring diagram I will be using:

I am still playing with how I am going to do the wiring. Does anyone want to critique this?

I fabbed up a new kickstand and mount, and moved it to the rear of the footpegs. There is a little left to do there, but after that, I think I am done welding on this little pony.

A little paint is next, followed by a little reassembly. Then, I cobble the stock wiring harness together, ride the thing home, and strip the wiring out for a rebuild. Luckily, I have a new MikesXS harness in the bike, so I SHOULD be working with new, correct color wires.