Re-re-reviving my '81 Seca 750

So, I started disassembly MONTHS ago (replace fork oil, steering head bearings, and fix the master cylinder AGAIN). Got as far as draining the forks, and then life happened.

Last weekend, I finally took the steering yoke apart and removed the old bearings. Also JB-Welded a broken tab on the instrument cluster. Tonight, I set the new bearings and reassembled the yoke. I started putting the forks back together only to realize not only do I not have enough fork oil, but somehow have the wrong weight on hand from the last change? Haynes says 20w, I see a lot of recs here for 15w. For some reason I'd put 10w in last time I did them . . . AGES ago. Not sure why. Anyway, to the shop tomorrow to pick up some proper oil - will probably go with 15w. Maybe I'll get it back together and start the arduous brake fill/bleed process this weekend. Maybe not. Hopefully it's not another few months . . .

 

I use automatic transmission fluid in mine.

 

Filled the forks, started reassembly. Forgot to put the handlebars on first, so control cables were mis-routed, so I had to drop the forks again, LOL.

Then when I went to re-mount my Atari console, the attempted JB Weld repair of the mounting tab failed.

Got the rest or the wiring reconnected and cleaned off my workbench to re-rebuild the master cylinder tomorrow, hopefully.

One thing I didn’t get a good picture of was the routing of the brake cable, or even which end is up. I assume the reinforced section goes down by the light bucket area, not under the handlebar cover?

 

The brake cable goes through the hole in the right handlebar cover, and is held in place by the clip on the bar itself. The the cable goes down behind the right side of the bucket.

the clutch side is a mirror image.

 

That picture shows me the section with the extra jacket goes down in the guts by the bucket. Perfect. Thanks.

 

Got the new rebuild kit in the mc today and based on memory, it feels way smoother and unforced on the bench compared to last time (about a year and a half ago, so who knows). Also have pressure and vacuum and the proper ports. Don't know if I had bad parts or installed them improperly last time, but I'm hopeful this time around. I mean I had reused the original spring. They don't feel much different, if at all, but maybe that's the fix.

Ran out of time to reconnect the pipe from the MC to the distribution block, but I hope to in the next day or two, get the wheel remounted, and get to bleeding.

Also found a local welder who is out of town for the weekend but is optimistic about doing a repair on the Atari bracket on Tuesday.

Moving along.

 

Remounted the wheel and I don't like the lack of gap between the right caliper block and the disc. I noticed it was really close when I replaced the bearings a year and a half ago, but it cleared. This time I feel a slight dragging. Left is ok. Axel spacers are in the only way they can go. Can't think of any adjustments for this . . .

 

Did you tighten the pinch bolt first, or did you tighten the axle nut first?

 

Axle nut first with a rod through the holes on the other side of the axle to stop it from spinning. I will slack everything up and take another run at it.

Was in a meeting and missed your call. Thanks though.

 

Loosened the pinch bolts and axle nut, and the bolts holding the fender, in case those were doing something weird. Re-torqued the axle nut and there's a tiny bit of clearance now and it's no longer dragging.

Have some pressure in the brake system tonight to where I can't turn the from wheel by hand when applied, but the lever still goes all the way to the handlebar. Leaving it overnight for the air to settle out and bleed again tomorrow.

 

It’s good practice to compress the forks several times before tightening the pinch bolts

 

Hmmm. Yeah, forgot reading that along the way somewhere. So when I get it off the stands, loosen the upper and lower fork pinch bolts, compress a few times (now that I finally have front brake pressure again, yay!) and re-torque?

 

The axle pinch bolt.
You want to make sure the suspension is not binding.
The brake clearance is important but the suspenders need to stroke smoothly, then tighten the axle pinch bolt.

 

Ok. Got it.

 

It's best to not totally tighten up one bolt at a time, but to do them all halfway, then all tight. It distributes forces more evenly and makes it less likely to cause binding, as you have seen.
In other words, a grunt first, then two grunts. A fart is right out.

 

For the brake purge/bleed, I cheated a bit since I had so much of the bike apart already. I pulled the handlebars and top yoke back off, primed the master on the bench with the cap/diaphragm off. Replaced it in the bracket with minimal spillage since I could move the bracket around instead of having to tip the reservoir. I then put the rigid pipe in place but not sealed, and reverse-bled from the caliper until the air was purged from the pipe. Then sealed the pipe, built up pressure in the MC, and burped the top connection 2 more times. After that, the plunger was solid. Topped up the fluid, put the diaphragm, cap, and bracket back on, then the yoke, handlebars, and brake cable. I let it sit overnight and did one more bleed of the upper union and all 4 bleeder valves (no bubbles) this morning. Nice firm lever.

Atari plate is being welded. Won't have much time to wrench tonight, but there's not much left to do. I hope to get a test ride in tonight or tomorrow morning, weather permitting.

 

If the fender bolts were “doing something weird”, that’s telling you something.....either:
1. Your forks aren’t parallel
2. Your fender is bent

either way, you’ve got some straightening to do.

 

That fender did take a whack once a long time ago. I've got a spare (what ever happened to Robert from San Diego, I believe?) that is cosmetically ugly (always meant to paint/get painted) but more structurally sound. I swapped it on this morning (a PITA which involved dropping the wheel again, and pushing one fork leg up out of the way). No real difference, maybe a SLIGHT bit more clearance. The wheel spins freely when the front end it lifted. I also quadruple-checked the speedometer hub was seated correctly and completely.

The mention of the fender got me thinking about the front-end collision I had about 15 years ago. I'd gotten down to about 5-10 MPH before impacting the car that pulled directly in front of me then stopped. Front wheel wedged between their front tire and fender. I had a Yamaha shop check out the bike at the time, but maybe they missed the forks being tweaked. Travel doesn't bind anywhere, there's no visible deformity, scoring, etc. Seals are good. But maybe they're bent. If so, they've been bent for 15 years (with a lot of down time, granted). Not sure what my next steps should be.

I did ride it last night. Felt fine, but at this point I really wouldn't know any better unless it were making odd noise, dragging, pulling, or sticking, which it's not.

Only problem I had getting going last night was despite draining the carb bowls when I pulled the tank and front end off last year, there seemed to be some boogers in the carbs. It stared up and idled nicely once primed, but when I tried to accelerate in 1st, it bogged and died a few times. I finally was able to nurse it up to speed, and by the end of my block, it was running right. Idled nicely at lights. Had no problem restarting at the gas station and she screamed like her old self on the way home.

Brakes still have a tiny bit of squish somewhere in them (what feels firm in the garage has a way of changing on the road). It's also possible that with all the bleeding and such I've done, the pads might be a bit contaminated. I'll see how they are after another bleed and possibly replace despite being 'new' (last year, only a couple hundred miles).

So, yeah. mixed feelings.

 

Easy way to check if forks are out of parallel:

1. get two perfectly straight sticks (broomhandle, etc.....

2. put on through the rim spokes, then roll the rim backward til the stick is firmly held against the fork lower tubes

3. put the second stick across the upper tubes as high as you can

4. sight down the tubes from the handlebars .... lining up the sticks in your vision.

5. compare the ends..... they should be perfectly parallel end to end. If they aren’t, your forks are out of parallel.
Loosen the tube pinch bolts just enough to to re-align them and re-tighten.