New to me XS750...need some ideas

Fleksta · Jun 17, 2018

The new bleed type pilots seem to have done the trick! I was still getting a pretty bad flat spot right off idle, so pulled the carbs again and raised the needle one notch. Seems to be pretty close now, starts on one or two kicks (starter button quit on me), and revs out like it should.

Next task is to repair the right rear turn signal wiring, fix the rear brake (no pressure at all, hopefully it is rebuild-able), and do a short road test to make sure 2nd gear is OK.

weaselbeak · Jun 17, 2018

I doubt you'll find the 2nd gear problem on a 78. Pretty sure they were sorted by then. 77's were trouble.

jetmechmarty · Jun 20, 2018

weaselbeak said:
I doubt you'll find the 2nd gear problem on a 78. Pretty sure they were sorted by then. 77's were trouble.

2nd gear blowouts are common on all XS bikes except the XS650. All the way through 1981 and beyond had the problem.

Fleksta · Jun 24, 2018

First road test was a success! Didn't go far as I don't have it plated yet, just to the end of my dead end road and back (1/8 mile or so). Got it up to third gear nice and smooth (but the real test will be harder acceleration). That triple engine is a torque monster, it just wanted to go :bike:

I had removed the back brake to rebuild, and I'm not sure I'll reuse the master cylinder. It's frozen solid and won't be budged after a long soak in penetrating fluid. The rear caliper looked like it was a lost cause, but after cleaning it good might be reusable. That piston was a real PITA to remove, but came out with some mini-sledge love taps :whistle:

.

It looks like there is an internal seal or O-ring, but the rebuild kit didn't include it. Think it's safe to reuse?

This master may be too far gone, it was full of rust but cleared up a bit after a soak in brake cleaner and some shots with the air gun. All the rust looks to have come from the metal plate under the cap:

Problem is, I can't get this piston to budge:

Making progress finally! Actually being able to ride it was a huge morale booster

gggGary · Jun 24, 2018

Yeah pretty rough all around, the caliper piston is quite pitted. 5twins found generic brake seals that should work. remove that one and clean behind it. That's the usual problem in disc brakes, all the gunk behind the piston seal. I've had success reusing that seal if it's not all beat up.

jetmechmarty · Jun 24, 2018

If that ring in the caliper is not in your rebuild kit, you have an inferior kit. It should have been included. Like Gary said, the crap under that seal is going to be an issue. Remove it and clean under there. Inspect the seal for any cracks. The pitting on the piston will be a problem. The caliper will leak there. Replace the piston.

The master cylinder will clean up. You'll need to remove the plastic reservoir. A packing (o'ring) on the bottom is holding it in place. That packing will also require replacement. A good parts house or hardware store should be able to hook you up. A snap ring holds the piston in place. It won't come apart until you remove it.

Fleksta · Jun 24, 2018

I've got the snap ring out in that pic, the piston still won't so much as wiggle. I found a much better looking master on ebay pretty cheap that I will rebuild instead. I didn't want to reuse the cap anyway, as it is just flaky rust.

It looks like these use the same brakes as the 650, so I should be able to get a replacement piston from Mikes. I'll hold off on that order until I have time to assess the front brakes too. They work, but are very soft. That master has the same rusty cap issue as well.

gggGary · Jun 24, 2018

Yes most if not all the yammies of that vintage use the same disc brake parts

jetmechmarty · Jun 24, 2018

Specials (other than the XS650) use completely different calipers. Is your XS750 a standard? If so, you're OK. Rear calipers may interchange anyway.

Fleksta · Jun 24, 2018

Yep, it's a standard with a goofy (but pretty darn comfy) king/queen seat on it. Over the winter I scored a mint stock seat with red side covers & tail for about a hundred bucks.

MaxPete · Jun 24, 2018

I always loved the XS750: big comfy, fast with great brakes, cast wheels and a shaft.

It was a toss-up whether to buy an XS750 or the roughly comparable Suzuki GS850G. I chose the Suzuki because the local Suzuki dealer was waaayyy better than the Yamaha dealer. I loved my big Suzuki but I still hankered after that triple with it’s neat exhaust note.

gggGary · Jun 24, 2018

Fleksta · Jul 16, 2018

Got the rear brake rebuilt & front's working well enough for a test ride. Took it on my go-to 50 mile loop and it performed great! Pulls hard all the way to redline.

The 3-3 exhaust sounds amazing, but I'm debating swapping back to the stock exhaust simply so I can put a center stand on it. I'll have to see if someone can make a new collector for the stock headers so I can use an aftermarket muffler instead of the enormous stock one.

Here is how it sits at present, I swapped out the king & queen seat for something more appropriate:

bigdawg · Jul 16, 2018

glad u got some valuable imfo on here...being said you was in the wrong forum

MaxPete · Jul 17, 2018

Looks nice - especially withOUT that.....remarkable seat :wtf:

Love those triples!

Pete

New to me XS750...need some ideas

Fleksta

XS650 Addict

weaselbeak

XS650 Junkie

jetmechmarty

Project collector

Fleksta

XS650 Addict

gggGary

If not now, When?

jetmechmarty

Project collector

Fleksta

XS650 Addict

gggGary

If not now, When?

jetmechmarty

Project collector

Fleksta

XS650 Addict

MaxPete

Lucille, Betty, Demi, Gretel & Big Sue money pits.

gggGary

If not now, When?

Fleksta

XS650 Addict

bigdawg

XS650 Enthusiast

MaxPete

Lucille, Betty, Demi, Gretel & Big Sue money pits.

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