Bring a piece of crap back to life(?)

Tomterrific

Hi Folks,

I've recently picked up a 77 with only 5300 miles on the clock. The problem is the original owner pushed her outside about 10 years ago. Sad isn't it? Surprisingly, a new battery and some either and the engine put-putted for a bit. She's got compression and spark! Now here is what I need to know: what unusual matters should I watch out for bringing this lump back to life? I'm a 55 year old amature mechanic who used to be professional so only the stuff peculiar to XS650s needs mentioning.

Thanks a bunch,
Tom Graham
Columbus, Ohio

grizld1

Nothin' weird to the '77 D-model. The mechanical spark advance unit often throws wide and holes pistons on the XS, but you're probably aware of that. Mama Yama says don't tweak the governor tabs to fix that, and she' ain't lyin'. I've seen certified mechanics do it, and I've never seen the tabs hold long after they did. The sump strainer often gets a hole sucked in the screen first time the wick's turned up. The reinforced unit from Mike's XS cures that and sells for less than Mama Yama's. You'll want to lose the plastic swingarm bushings and install bronze or needle bearing units. You're probably aware of that, too. One thing that gives guys fits is oil seep at the head gasket. Everything from barrel to head cover is assembled on the same long studs, 2-stroke style; doesn't take much imagination to figure what a 40-cube twin does to that after awhile--gotta keep after it with the torque wrench, it's a weird design. Everything else is pretty straightforward. Welcome aboard--enjoy!

650rider · WebMaster Joined: Feb 09, 2005 Posts: 431

Hi and welcome,
Sounds like you got a great project bike. I'm not much of a mechanic but I'm putting this in just because I forgot about when I got my 77-D. The fork oil. . . Change the fork oil. Good luck.

Tomterrific

Thanks grizld, I didn't know about the problems with the advance or the oil strainer. I'll need to order gaskets and check that the strainer is okay after I get the bike sorted. I've been in the advance and it looked fine compared to the nasty outside of the bike. The advance had never been lubed so I hit it with some 30wt. to get it loosen up. I'm brand new to the Yamaha 650 since I've ridden my Triumph Bonneville since the early 80s. I've been a bike owner since 1967. I know nothing about the XS or where to get parts (but I know plenty about general motorcycle mechanics). Nice that the swingarm bushes are tight and I could not detect any play. Easy to grease too but I bet a bunch of owners never did it.

Russo, fork oil on the long list. I plan to have a Rat Bike but one that runs well. Basically the bike is RUST! Too bad as it seems to be in good shape if it didn't sit for years in the rain.

Keep anything specific to the XS 650 coming. I need to know this stuff and experienced guys to talk with is the best way to learn.

Tom

grizld1

Tom, the best general parts source is Mike's XS. I take it the fork tubes are rusty as well; if so they aren't hard to find in good used condition, or Forking by Frank in Evanston, IL sells new ones for just north of $200 a set. The swingarm bushings may not permit play when you check 'em by hand, but the plastic flexes under load; an unbelievably cheesy setup. If you're used to a Bonnie, you probably won't be too pleased with a swingarm that's got the rigidity of well-cooked pasta. Bar mounts usually need to be tightened up, too. The quick fix there is to drop the bar mount stem nuts and the washers under them and fit in a few washers with a big enough ID to clear the shoulders on the bar mount stems and small enough OD to fit into the bar mount damper holes in the upper clamp. Just reinstall the original washers and crank down; those rubber dampers will squish out and tighten up fine.

The advance mechanism may look dandy, but it's a treacherous SOB. But, hey--you've been at this awhile. If you need to fix it, build up the weights in the contact area rather than messing with the tabs. I've had better luck (10 years of dependable service) from the old Boyer 4-stage ignition than the new Boyer microstep, and the 4-stage units are still around. Both get rid of the advance unit, with the bonus of lightening things up a bit in the head.

If you get new shocks, the scoot handles better with the tail up a bit. I like 13.25" eye-to-eye.

Haven't owned a Trunch since my '68 Bonnie got ripped off back in 1970; the beast ran like stink when it was dialed in, but I must have worn out three timing lights keeping it that way.

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Yamaha xs650