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new project (xs750)

6K views 19 replies 11 participants last post by  HackAsaw 
#1 ·
Alrighty, thinking about sculpting this '79 xs750 triple into a cafe racer. Looked around the net and haven't seen many cafe xs750 but I don't see why it's not possible. So before I start it, I'd like to know if in your opinion it's a good base.



 
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#2 ·
My main concern with this is lack of parts and potential problems. I would of course prefer to get ahold of a cb750 but where I live such things don't exist very often. And this one here is a good deal. So if anyone knows if there's a supply of 'cafe' parts for it and any potential problems.

Also, I know there's no exhaust on it, current owner says he has a mac 3 into 1.
 
#3 ·
Where do you live? I have twp CB750 for sale, a 75 and 75. I think the XS would be a great cafe. Parts are not impossible to find but the CB is by far easier. Might be nice to have something different though
 
#9 ·
quote:Originally posted by FR

It's a nice looking bike to begin with, nice tank, not a bad seat and tail section. I think those bikes have great potential..


FR
I agree the bike in the pics has a lot of potential already built in to it.

The deal is the Yamaha triples were not built as performance machines and just weren't known to be real power houses. There also isn't a lot of performance parts for them. That doesn't mean they can't be turned into a cool looking bike.

Use the stock tail and move it forward a few inches. Reuse the stock seat pan. Cut down the seat and have it form into the rear tail to create a bum stop and make it a solo seat.

Use the Mac header pipe and buy a cheap $40-90 cone tip muffler(J.C. Whitney and other suppliers sell them).

Mount a smaller tail light into the tail section,chop the rear fender,lose the ugly grab rail,chop or remove frt. fender,put on smaller turn indicators,cover up the electronic/battery with stainless/Aluminum or stock covers,add rear-set pegs,clip-ons/clubmans etc.
 
#10 ·
Quote:
"Yamaha triples were not built as performance machines and just weren't known to be real power houses. There also isn't a lot of performance parts for them."

i love the sound of triples....but from what i understand about those rigs...start with something else. a friend had one in his garage for years and couldn't get any one to take it (for free). begged me to end his misery but i let him continue to suffer with it.
-parks
ps...i think the "xs" precedes "weight"....
 
#13 ·
I have a future plan for an XS750/850. I like the concept of a triple cause they are different and sound cool. The problem with using the XS as a start is that it has poor suspension, brakes and wheels, plus shaft drive. I plan on converting it to chain drive. The output shaft assembly is a bolt on box that just plugs into the output trans shaft. It shouldn't be too hard to make a bearing supported sprocket shaft. Once you look at it, it all makes sense. Then I would put the motor into an FZ600 or FZ750 frame depending on fit. They both have steel perimeter frames so they can easily be welded on. The other issue with the XS750 is access to the valves for tune ups. In the stock frame it is a pain so a perimeter frame would allow the valve cover to come straight up and out. This will be a total e-bay kind of project that will won't take too much cash. I am going to start up collecting up more parts as I go along, but XS750/850s are available cheap and all over the place.

If you are going to keep the shaft drive and the original frame then I would look at the rear wheels off the Seca 750 or 900 to get a wider rim. I would also look at the rear swing arm off the 81-83 Virago and see about going monoshock for something different.

I think the Yamaha triples are a great base for a different Cafe.

Ken
 
#15 ·
Parks,
I think I addressed those issues. Get rid of the brakes, wheels, suspension and shaft. Just keep the engine.
Ken
 
#16 ·
I love the Yamaha triples! If you care for them they go for frigging ever and as noted above....they sound cool.
As for parts aftermarket....there's stuff out there, you just have to look.
Overbore pistons can be had via an XS1100 kit minus one slug or if you wanna get creative. Megacycle makes cams and they really wake up with some port work. The stock diaphragm carbs suck, swap to something better. Mikuni VM series work great.
Pipes are available as well but Mac is most common, run one with a large bore reverse cone muffler and you'll be golden.
100hp isn't out of the question if you are up for the work.
The gearbox issue is actually with 2nd gear popping out and there's a clip that you can remove from the assembly (without teardown) that takes care of it.
As for the suspension being suspect.....ever riden a CB750? That'll be a barge too until you rework what's there.
Shaftie....so what? Guzzi makes shafties too......nobody whines about that.
Go for it!

Good resource here: http://www.yamaha-triples.org/
 
#18 ·
I like the Yamaha triples. One thing to look at very carefully, before getting carried away with dollars/work thrown at one, is spending 15 bucks having oil analysis done. Why? Because the XS triples had terrible fuel petcocks (and if your analysis doesn't indicate you may have serious bottom end problems replace them with pingel's adapter plate and real petcocks) that would allow the contents of the fuel tank to end up in the crankcase. Many of these engines were wiped out when an owner started and ran them with fuel diluted oil.

The biggest favor you can do is get shed of all the flab but I'm not opposed to the very reliable and trouble free shaft setup. The engine actually isn't any heavier than a CB750 and stock for stock, I think the XS will walk right away from the CB.

I hate the overly complicated electrics, strip all that and simply rewire with a solid state box.

You can do 900cc's on them easy, like previously mentioned, you can get cams too.

The stock carbs that are horrible are the two piece bodied Hitachi units. Throw them as far as you can. The One piece Mikuni CV's are fine but parts are pricey if you buy them from Yamaha. I bought the two fuel "t's" that hand fuel over from one carb to the other, thru my dealer account thinking they'd be little or nothing....... wrong......... 54 bucks and that was 8 years ago. I also ordered other bits for it at the time and ended up spending a bit over 200 bucks for just a few parts.

Had I known, I would have simply built up some VM's from a triple Kaw (easy because the three way cable enrichener is one less thing to fuss with, but not so cheap to snag a set of those these days) or even adapted Mark II Amals, easy enough to put any number of other mechanical slide carbs on it.

The stock headpipes are ok with some decent mufflers but you have to keep in mind these have a flat (180 degree) crank and don't respond as favorably to a simple 3into1 header, as a 120 degree crank triple does. I've heard the Hooker pipe, although a bit odd, works well. I've never owner or ridden a bike fitted with one.

But you can easily get enough useful horsepower out of one, even using just the later stock cam and not spending large for the megacycle (about 480 dealer? last time I checked?) stuff, with just common sense tuning. I'd do the big bore before I spent for cams and then port work with a nice valve job before cams. Chamber detail too.

BTW, engine gasket sets are not cheap last time I priced them. I recall being shocked. Maybe they've since become cheaper.

The frames are very stiff, I actually "hardtailed" one several years ago so I've cut into the frames and ridden several, stiff enough and I'd think some larger diameter large bore bike forks off most any 82ish and up liter plus performance oriented bike

or even more modern USD forks

cool how that stuff is stronger, lighter, and even works better than the old heavy flimsy stuff

would go a long way to making one cafe useful, that and some good rear suspension units

good luck and hope the engine is in good shape

have the oil checked out, better if you do it after you have it up and running, but if you do get it running and change the oil prior, don't simply throw it away without having it checked

a before and after analysis would be great, who knows if you get it fired up and hear those mains rumbling, you may be inclined to look for something more viable, like an XS that isn't hurt
 
#20 ·
here is the one I hardtailed several years ago

I have no idea why I didn't stick with the red paint

Never registered with me that silver and blue made it look like a CHP bike since I didn't grow up with a color TV





it was plenty swift
 
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