Yet another XS750 café inspired build

Hello world,

Since I recently sold my car (1960 Volvo 544) I've been experiencing a feeling of loss, a gap somewhere between my belly and my heart where the mechanical anxiety over whether or not I'd be able to fix the car this time used to be. I figured this would be a good time to finally go and get my motorcycle license, and to do that I needed a ride, so here it is. 1978 Yamaha XS750, with a Marshall 3-1 exhaust and one hideous bright yellow paint. It was running fine when we picked it up, except the front brakes called it quits on the way home, it was idling at about 4000 rpm or so, and the tires turned out to be more like a pair of ice skates (and oh, it started to rain when we were half way home).
As the riding season has pretty much reached its end here in Sweden (expecting snow by tomorrow), the idea for the next couple of months is to get all the mechanical necesseties working like the brakes, the clutch, and rebuilt carbs. I figure the high idle is probably caused by the dry cracked up inlet rubbers, but I'm gonna clean 'em and change everything removable on the carbs anyways. Also I'm gonna try and get some of the aestethics right with a bare polished tank, new air filters, clip-ons, and details in fresh black paint (except the frame which will be dealt with next winter along with the engine). When it comes to the seat I haven't quit made up my mind about whether to do it with fiberglass, as a first-time welding project (probably not such a good idea, but you gotta try it to learn anything right), or just make it a long flat seat as I would like to retain the possibility of riding two on it, and the upholstery part is something I feel confident doing...
Now all the experience I have comes from a life-long tinkering with anything and everything mechanical, the old Volvo, and all the mopeds I've modded through my adolescence, so any tips, tricks and ideas are warmly welcomed.

Cheers!

Subscribed. I love seeing more triples.

I'm glad for the triple support!

So the tearing-down process has begun, cleaned out the front calipers and got some new pads in the mail along with a completely new master cylinder as the old one turned out to consist of mostly rust. Gonna try and soak it in solvent and see if I can beat the piston out of there as I've got a spare kit for that one as well, and maybe sell it to pay for some other part.
I'm in doubt about whether to cut the rearmost part of the frame and weld a loop to it, or to make the seat so as to hide it as I would like the entire build to be reversible in case my insurance company doesn't approve of my rebuild. As I've got it on a 'Classics' type insurance any rebuild has to be "typical of the era"...

Subscribed also, Ive got a XS750E I'm tinkering with.

Look forward to seeing how you progress this winter!

Subscribed to yours as well! I'll be adhering to the 'built not bought' creed as well (as I haven't got much of an option), which unfortunately means no updates here as I've been tending to other projects in wait of new funds.

Haven't posted here for about a year. The rebuild grinded to a halt last winter as I realized I wouldn't be able to finish everything (or anything) I wanted to do before riding season as there just wasn't enough time. So, I put the bits and pieces back together and rode it practically like it looks in the first picture. Soon realized the carbs weren't up for the job as I blew clouds of smoke wherever I went (it even got me pulled over but the cops just laughed and sent me on my way). Well, as long as it's moving forward is my philosophy.
However, here's the status today as the riding season is pretty much over. I installed clip-ons, lowered the headlight a couple of inches to make place for 'em and to better adhere to the lines of the bike, got myself a small range of main jets to tune the carbs (which will have to wait until spring since I don't have access to a dyno), and cut the back of the frame to make place for the loop I'm having manufactured as we speak. And oh I also drew up a new speedo face inspired by old Smiths-speedos, and I intend to make it an intergrated tach by marking out the revs per gear between the inner lines, so that I can drop the tach and just have a centered speedo. As I haven't found any reliable way of calculating this it will also have to wait until spring when I can record the revs for every gear. Unless of course anyone out there knows how to calculate this or is otherwise knowledgeable about the subject?

And if anyone is wondering why I only have space for revs up until fourth gear it's because a) it didn't look as neat with more of them and b) I'm not really worried about accidentally redlining this heavy old thing in fifth gear. As you already will have guessed it's in kmh btw.

If you know your gear ratios you can use this: http://www.cryohold.com/bike/gears.html
However, getting the gear ratios could be tough. I did it by counting the teeth on each gear, since I had the engine completely torn down when I did it. I know its in MPH, but converting to KPH shouldn't be too hard

Another triple fan here. I'll keep an eye on this one

CALfeRacer said:

If you know your gear ratios you can use this: http://www.cryohold.com/bike/gears.html
However, getting the gear ratios could be tough. I did it by counting the teeth on each gear, since I had the engine completely torn down when I did it. I know its in MPH, but converting to KPH shouldn't be too hard

Click to expand...

Great, just what I needed. I've seen others but designed primarily for cars, and I kinda sorta know how to calculate it manually as well. My main problem still remains though: the ratios. As it's shaft driven I just can't figure out how or which of the multitudes of gears to include in the calculation. I've gathered the separate ratios from literature, so the transmission output is 34/32, the middle gear 19/18 and the final gear 32/11, but how do I calculate the total front-to-end ratio? I'm not foreign to mathematics and know there's an easy answer to this, so if someone could just point out the obvious I'd be glad to wear the dunce cap for a day or two.

Nevermind... Just realized all I have to do is multiply them! But doesn't 108 mph at 5000 rpm in fourth sound a bit off?

Alright another triple!

That speed sounds off, pretty sure I have to nearly rev out 5th gear to hit the 110mph spot.

Yeah, it's just something I can't seem to get right. I'll keep on tinkering with the numbers 'til they feel right. On a brighter note though, I got my hands on a sander today and had a midnight session stripping the paint off the tank. I had been warned sanding takes forever, but this is what I achieved in 15 minutes and I'm totally pleased with that and not having to deal with any deadly slimy paint stripper. The neighbours weren't, however, as two of them came down asking if I was tearing the building apart So 15 minutes is all I got, plus a yellow floor. And walls. Pretty much yellow everything

Making slow progress sanding the tank down, not because it's especially tedious but because I'm spending all my time working to afford to have free time, which I don't have since I'm working...

Looks like you have a pretty clean tank there. I have yet to find one without a few good size dents in it.

The dents are indeed few and small, and also they're concentrated to the bottom, which makes me wonder how they've handled this bike...

Replaced the old cracked plastic fuel t-pieces for new stainless ones. Also double checked the main jets before ordering a new array for tuning and much to my surprise I discovered they were 150's. I had assumed it was running lean, but how common is that with mains of that size..?

gentlemanthief said:

Replaced the old cracked plastic fuel t-pieces for new stainless ones. Also double checked the main jets before ordering a new array for tuning and much to my surprise I discovered they were 150's. I had assumed it was running lean, but how common is that with mains of that size..?

Click to expand...

I like!! Where did you get that "T"?

Subscribed

Yeah, feels better with replaceable o-rings rather than having to replace the whole thing next time. Looks fresh too! Found 'em on ebay.