CM400E tank

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CM400E tank

Postby michael_650 » Wed Sep 07, 2016 12:52 pm

I just recently picked up a 1981 CB650 and took it for two short rides before setting in to "make it right." Pics to follow in the next few days. Not having had a street bike before, I didn't realize exactly how much it was missing, but I'm not afraid of a little work. Motor ran strong (starts warm, doesn't like to start cold), brakes are good, trans shifted smoothly. The owner didn't have the title, but he was still friends with the guy he got it from, and he DID have the title and was willing to meet up with us after work one night. The title came up clean through DMV, so the bike came home with me
Here's the "so far" story:
1. Solenoid: Half of the old solenoid was missing. Yes, missing. Previous owner had hard-wired in a push-start button from a tractor and screwed it to the battery tray. The button produced smoke if you pressed it for more than a few seconds. New solenoid from ebay turned out not to be 100% fitment; the wiring harness wouldn't fit; custom wiring work, it's now "right."
2. Side panel: one was missing, so he cut a triangle out of sheet plastic, drilled three holes, put a nut/bolt on, and pressed it into place. It didn't look completely horrible, but it needed to be replaced. ebay, sanding, priming, painted. It's now "right."
3. Tank: several (many) rust holes. He used an epoxy (which never quite cured to a hardened state) and aluminium tape. Questionable at best. I have tried several varieties of tank repair, but all failed. I went to a motorcycle scrap yard and located a tank with exactly the same mounting points. I took it home, and the petcock turns out to be located exactly over the carb vacuum bowl. There's only a 1" clearance between the bottom of the bung and the top of the carb. A visit to a local hydraulics establishment yielded information (it's a 3/8" NPT fitting) and some new brass fittings and shut-off. Yes, I have no reserve, but will be outfitting the bike with an emergency gas container. Tank turns out to be from a 1980's era CM400E. It has a locking lid over the gas cap and some cool styling lines that are just begging for hand pinstriping. It was probably brown once, but has a really cool brown/purple patina and crackled-paint feel about it, and I may keep that as is.
4. Tach: MIA. While at the junk yard, I found one from a 1981 CB750.
5. Dash: Busted up and hanging by the wires. While at the junk yard, I found a dash from a 1981 CB750, conveniently mounted to the tach I found.
6. Instrument cluster mounting: Discovered the CB750 mounting plate does not fit the CB650. With some gentle loving, the CB750 dash and tach now live on the CB650 plate. Also discovered the wiring harness, while a physical match to the 650, is wired very differently. Simple solution: Graft the 650 clip to the 750 instruments. Solved.
7. Choke cable: MIA. New replacement part from ebay now in place.
8. Tach cable: MIA.
9. Front blinkers: MIA.
10. Carbs: Dirty. Actually, "dirty" is being generous. I soaked them in Simple Green, cycled them through the ultrasonic cleaner from Harbor Freight for about 30 minutes. Unfortunately, now I discover that the bowl gaskets have given up the ghost and leak profusely. Back to ebay, and I'm in wait mode until they arrive. Mostly original clips on the carb boots, but about half a dozen of them are off-the-shelf hose clamps. Eventually planning to replace them with stock.
11. Carb/manifold boots: Wondered at first if these had been repaired with electrical tape. Nope, they were just deformed and delaminating after years of use. A new set of 4 on ebay ran me $75 including shipping.
12. Turn signal relay: took it out to inspect it, turned it over to look at the manufacturer's marks, and water poured out of it. Simple to replace.
13. Battery: replaced.
14. Oil change, oil filter, spark plugs replaced.
15. Air filter: K&N. Not sure if it's after-market, but it hung in the hole loosely, no clips. Made some clips from sheet metal, drilled through holes, screwed them in. No air leaks now.

What's left:
The chrome work is slightly rusted, but Mother's metal polish, a rag, and Michael's Elbow Grease go a long way. The aluminum on the motor is looking all of its 35 years old, It will get the same treatment as the chrome. It could probably use new tires in the spring. The brake master cylinder has two drywall screws holding the cap in and is wrapped in electrical tape. No leaks: this puts it on the "doing it later" list. The threads in the mirror mount holes are stripped. I'm putting on some aftermarket mirrors I had laying around; they have their own handlebar clamps. I'd prefer to have wire wheels over these Comstocks; I'm open to a trade but don't want to lay out cash right now.

Thanks for reading. Can't wait to get it on the road.

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