78 xs750 special build

[Mr.Wilde]

well, after a summer of having this bike for my number one riding machine, i have come to the conclusion i like it more then my 2004 dakar! but now the time of year has come to park it in the garage and take things apart to make them better. new cam chain, primary chain, piston rings, lot of other small things, and a bit of a make over as well. but i thought i would start with something easy. so i have started on fixing up the standard xs750 tank. blasted it with glass the other day and not to my surprise, found some small holes near the fuel tap. never patched a tank before, but i'm guessing that it can be done with a tig welder? i have no welding experience at all, but my uncle sure does. he just finished restoring his '65 chevelle convertible and did EVERYTHING out of his garage.

 

[john83]

Love these old triples. I'll follow along.

 

[alambie]

Agreed, nice build man. I've got a 79 xs750 special that I'm rebuilding, its good to see some of these still around. Have you check out the yamaha triples blog as well? They have got a ton of great members, info, and manuals to boot! Those guys have helped me through some tough snags.

 

[Mr.Wilde]

Agreed, nice build man. I've got a 79 xs750 special that I'm rebuilding, its good to see some of these still around. Have you check out the yamaha triples blog as well? They have got a ton of great members, info, and manuals to boot! Those guys have helped me through some tough snags.

yes i have! such a great site. the info has helped me out with a lot of frustrating jams.

haven't really got a chance to work on anything this week, due to house sitting... but on a brighter note, my lady just bought her first bike! a '77 XL350. i'm a little jealous haha.

trying to think of the best way to patch my tank. i cant get my hands on the proper welder, so i'm thinking of some sort sealant. i'm going to coat the inside of the tank any how so i'm not to worried about whats fuel resistant or not. what are your thoughts? take it to a shop and get it done right or find some filler and go to town?

 

[Mr.Wilde]

looking pretty good...

except for the holes!

 

[Mr.Wilde]

tried out the clubman bars on the bike and i have some to the conclusion that i don't like them. i can make them work if i tap in the tank and get rearsets. but for now i'm thinking of drag bars!

 

[Mr.Wilde]

finding used parts online in the same city is awesome. 3-1 exhaust, oil-cooler, 2 wiring harness's, alternators, starters, engine side covers, and a bunch of other crap. picked up some new drag bars too. time to have some fun!

 

[Mr.Wilde]

well, just got back to work on the bike. couldn't do shit all for a week and a half due to a rad cap blowing off a forklift i was driving. 1st and 2nd degree burns on my back, neck and arm. could have been worse though. was revering and had just looked behind me a second earlier. just glad the my pretty face didn't get disfigured! haha

so, got the 3-1 exhaust on, but i need to make a bracket for the muffler, doesn't want to line up. i think i'll get a shorter muffler down the road, but for now this will do. i'm thinking it might be for the standard model or a 850, maybe it has a different mount?

still haven't patched my tank up yet. hoping to use an oxy acetylene torch and acid core solder. but haven't found one yet. i might have to sink to a new low and take it to someone at a shop to do....

swapped my scratched and cracked engine side covers for some cleaner ones

drag bars are on. need to get shorter cables and a break line though. but i like the feel and the look.

aaaaannnnddd got an old street sign to make a new seat pan.

 

[Wahoo650]

My daily rider is a 1980 850 special. Love it to death. So far have left it stock since I have the 650. Watching this closely...

 

[Mr.Wilde]

My daily rider is a 1980 850 special. Love it to death. So far have left it stock since I have the 650. Watching this closely...

i was hoping to get an 850 when i was looking for an old triple to work on. but can't complain, cuz i love my 750 to death also. great bikes. the budget bmw's.

 

[m511y]

subscribed

 

[Juggernaut]

Looks like a slow and steady build. Keep me posted. If you have any questions about anything don't be afraid to email me.

 

[Swagger]

Fantastic platform, the 850 was my first "big bike"..

Looks like you made a safe choice as far as the header it concerned. The factory 3-1 (with the pretty, dogleg pipes has a collector that's designed as the pivot point of what could potentially be an Olympic grade high side.

When you find the time the 850 top end, especially the head is a palpable improvement on it's own but if you get really deep into them there's LOADS of potential.
XS1100 and FJ1100 valves are 2mm over size and can be set into the 7/850 head and with some porting can do nice things for power over all. The 850 cams are a little pokier but if you're looking for 5-6 more by themselves, Delta cams reground a set for me several years ago that really held up well. You can bump up to 900ccs with three of four pistons from an XS1100 1200cc overbore kit. Thinner base and head gaskets can boost compression a bit but nothing works as well as skimming 25 thou off the cylinders (doesn't change the combustion chamber that way). The later factory electronic ignition is good with pretty hot street cams, just convert the coil signal to 5v and use it to fire GM LSx "coil near plug" coilsets for a really good ignition that'll serve most anything you need it to until you get really wild. Next grab yourself a set of Mikuni VM34's and you should be bumping the 100hp mark.

Chain drive conversion is pretty do-able but if you go that route please please move the swingarm pivot closer to the engine to keep your chain tension in control.

(sorry, I cna go on forever about this bike and I'm three Manhattans down already tonite....

 

[Mr.Wilde]

Fantastic platform, the 850 was my first "big bike"..

Looks like you made a safe choice as far as the header it concerned. The factory 3-1 (with the pretty, dogleg pipes has a collector that's designed as the pivot point of what could potentially be an Olympic grade high side.

When you find the time the 850 top end, especially the head is a palpable improvement on it's own but if you get really deep into them there's LOADS of potential.
XS1100 and FJ1100 valves are 2mm over size and can be set into the 7/850 head and with some porting can do nice things for power over all. The 850 cams are a little pokier but if you're looking for 5-6 more by themselves, Delta cams reground a set for me several years ago that really held up well. You can bump up to 900ccs with three of four pistons from an XS1100 1200cc overbore kit. Thinner base and head gaskets can boost compression a bit but nothing works as well as skimming 25 thou off the cylinders (doesn't change the combustion chamber that way). The later factory electronic ignition is good with pretty hot street cams, just convert the coil signal to 5v and use it to fire GM LSx "coil near plug" coilsets for a really good ignition that'll serve most anything you need it to until you get really wild. Next grab yourself a set of Mikuni VM34's and you should be bumping the 100hp mark.

Chain drive conversion is pretty do-able but if you go that route please please move the swingarm pivot closer to the engine to keep your chain tension in control.

(sorry, I cna go on forever about this bike and I'm three Manhattans down already tonite....

daaaaamn man, thanks for the awesome post! i'v heard about the swapping the head, and also using triumph carbs. now i want to do everything that you have just mentioned. just got to take one step at a time. haven't had anytime lately to work on the bike, due to the christmas, my birthday, getting drunk with the family, new years and what not. but, i have made a shopping list that i will be ordering. in a week or so i'll be as happy as a pig in shit.

 

[Swagger]

Sounds like fun to be had! let's see.......

Chassis stuff if you stick to shaft drive....hmm, ok!
A *relatively* easy monoshock swap is to run the swingarm from a first gen Virago after a little rework on the pivot tube area, sling on an R1 take off and a simple top mount. Cake. If you want to stick with twin shocks look for something longer, the KYBs from a ZRX11 or 1200 are rad. Whatever you do not much more than 14.5" long back there or you'll need to relieve the universal....not worth it. You'll also want to have a well designed brace welded to the swingarm as well as a tube bracing across that portion of your frame.
The stock forks are a joke at best on this bike. Set'm aside for that someday sr250 scrambler project. There are loads of nice front ends on ebay for almost no money so have fun. A 41mm CBR/FZR etc front end (pre-usd) can be a fantastic standard style setup, still looks period but fully modern internally...good shit Maynard.
The 18" Yamaha front mag has their standard bolt pattern that allows the later LARGER FZR front discs. Calipers are easy so choose something with a well matched master cylinder.
Out back I have run a 140/80-18 on a 3.5" Kosman widened rim ($$$) but it required cutting a flat area into the swingarm where the tire needed room and welding in a flat piece. It was VERY close to the driveshaft but cleared ok. Anything wider will require weird offset or chain. You should look into bracing the neck a bit as the stiffer forks and better brakes will stress this area to flex.

 

[Mr.Wilde]

swagger, you are a wealth of information! i will eventually get around to a few things you have described.

so after a failed attempt to make a seat pan out of a street sign, i've decided to go with the old fiber glass trick. it's a little trickier, because i want to have a 2up, with a full fender. i really wanted to use the tail piece from the standard modle seat, but because i'm fussy, it's just a little to wide for what i want. i want the seat to be the same width as the frame. so i will be making my own. pretty much the same thing, but scaled down.

made up a simple braket for the new tank. just using the same mount for the old tank, also going to use it to mount the new seat. if someday i decide to swap back to the old one (i highly dought it), it will take hardly any effort. patched the gas tank, primed it, and just waiting for it to dry before filling in some small dents with bondo.

still haven't decided what colour i want to paint it... might go with pearl again, or maybe something a little more exotic. i thought about getting one of my friends to do a little pin striping. nothing crazy, just some simple, tasty, accents.

wish i had more to report. been to busy with the job and getting my ladies XL350 ready for her first season.

 

[Bubbaknoxz]

Great build, I'm working on a XS750 Special as well, so I will be watching this thread.

Quick question, for the tank swap did you do any modifications to the front mount on the frame as well?

 

[mikewerx]

watching and waiting...

 

[Swagger]

Doesn't running a standard tank on the Special front pucks make it susceptible to fork bashing? Can't remember...
Hope not, that'd suck.

 

[New2meCB]

Man, I so love those bikes. 8)

Very nice so far. Keep it up! Looks great 8)