'76 XS750 Triple

B

betz74

New Member
I bought a donor for my '76 Triple and it was in good enough shape that I decided to make it a cafe racer instead. I soon realize 2 bikes to work on was 1 too many for me right now. However, I got so into the idea of a cafe racer I decided to cafe out my daily rider and make the donor a donor again. I am almost done my seat, which has taken forever. Right now I am mainly going for the look and hope to start stripping weight in earnest if I can accomplish this much first. I have gotten a lot of tips on here so far, and am open to any and all suggestion.
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Question, I need to cut off about 4" from the end of the frame. Just where the turn signal mounts are. I was going to remove the gas tank first, but is there anything else I need to take off for safety? Carbs?
 
if you're going to cut your frame with a grinder, make sure you use a cutting wheel and not just a grinding wheel. It will make the job easier, less sparks flying around.
Just cover the carbs with a towel. Besides the spars should be going sideways not towards the engine bay. make sure you dust off or blow off the bike when you're done grinding or cutting away as small metal particles will get near and or on the engine bay or part of the frame and oxidize with time and live you with rust spots all over.

Eddie
 
LOVE the XS triples!

Here's some goodies for you:
Carbs and headers from a Hinkley Triumph triple will fit with minimal work. 750/900cc Daytona, Sprint etc....
The carbs are a bolt on, the spacing is so close that it's a matter or tolerance more than measurment and they are mile beyond what the OE carbs on the Yam will ever be. Cheap way to get good performance carbs, even if they are vac carbs, the boys at Triumph did a good job. Throttle response is quite on par with the VM series. To use a Triumph header it's nothing more than having your spigots welded to the header. The cradle spacing in more or less perfect too so the pipes aren't going to droop low under the belly.

That motor responds to port work VERY well.....like 10 basically free hp and 10-12ftlb.
Swap to the OE electronic ignition, it's every bit as good as any aftermerket piece and you can get all the parts off ebay for $35-45. I've used Delta Cams HP grind in my 850 and it really wakes up this lump, they weld and regrind based on your cam...last time I talked with Johnny (Rocket) I believe it was something like $65 a cam.....cheap cheap power and they hold up well. Swap to a 79+ oil block and run an external oil cooler...your engine will thank you. Without they run a bit warm in my opinion.
The flywheel is pretty chubby, you can lighten it probably 25% before you see any idle issues and I've run one (total loss) without a flywheel at all and it worked fine.
Get a Barnett clutch and spring set, you'll be happy and your bike won't chatter if you're flogging it hard. Changing the pumpkin to one from an XS1100 will net you wheelies all day long (taller gears) and you'll still be able to do 110+ in stock form.
what else.......
if it pops out of 2nd gear don't panic, it's a 20minute fix that shouldn't cost you more than $15, look up 2nd gear+shim for more on that.
Give those forks to someone who doesn't ride hard...they are damped ok but really REALLY flexible. I picked up a set from a BMW K75 (40mm Showas), same forks on the early 90's GSXR and a couple Yamahas. Good stuff and can be had for under $100 in good shape.

Hope this is of some help....have fun adn great choice!
 
Swagger said:
LOVE the XS triples!

Here's some goodies for you:
Carbs and headers from a Hinkley Triumph triple will fit with minimal work. 750/900cc Daytona, Sprint etc....
The carbs are a bolt on, the spacing is so close that it's a matter or tolerance more than measurment and they are mile beyond what the OE carbs on the Yam will ever be. Cheap way to get good performance carbs, even if they are vac carbs, the boys at Triumph did a good job. Throttle response is quite on par with the VM series. To use a Triumph header it's nothing more than having your spigots welded to the header. The cradle spacing in more or less perfect too so the pipes aren't going to droop low under the belly.

That motor responds to port work VERY well.....like 10 basically free hp and 10-12ftlb.
Swap to the OE electronic ignition, it's every bit as good as any aftermerket piece and you can get all the parts off ebay for $35-45. I've used Delta Cams HP grind in my 850 and it really wakes up this lump, they weld and regrind based on your cam...last time I talked with Johnny (Rocket) I believe it was something like $65 a cam.....cheap cheap power and they hold up well. Swap to a 79+ oil block and run an external oil cooler...your engine will thank you. Without they run a bit warm in my opinion.
The flywheel is pretty chubby, you can lighten it probably 25% before you see any idle issues and I've run one (total loss) without a flywheel at all and it worked fine.
Get a Barnett clutch and spring set, you'll be happy and your bike won't chatter if you're flogging it hard. Changing the pumpkin to one from an XS1100 will net you wheelies all day long (taller gears) and you'll still be able to do 110+ in stock form.
what else.......
if it pops out of 2nd gear don't panic, it's a 20minute fix that shouldn't cost you more than $15, look up 2nd gear+shim for more on that.
Give those forks to someone who doesn't ride hard...they are damped ok but really REALLY flexible. I picked up a set from a BMW K75 (40mm Showas), same forks on the early 90's GSXR and a couple Yamahas. Good stuff and can be had for under $100 in good shape.

Hope this is of some help....have fun adn great choice!
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Wow, thanks. I did get this bike because I love the Triumph's but am on a Japanese budget. Are you running clubman's and rearsets. I am putting on clubmans and wanted to go with rearsets mounted to the rear footpeg holes but am not sure if this is the way to go. I would love to hear what another xs rider is doing. I will save this list and shoot for some of the mods once I get a little more comfortable. This is my first project and I just wanted to get my feet wet and get it on the road. Here is my short list for what I want to get dome before riding season.

Cross Drilled Rotors (I know a guy)
New Tires
Fork Gaiters
Cafe Seat
Clubmans
Mini Stalk Signals
Bar end Mirrors
New Muffler (For looks, the old one works fine)
Some Paint
Rear-Sets

Thanks again, and I will definitely save this post. These are all great suggestions and If I have success with the more basic stuff, I definitely want to go further.
 
The XS750 scored better than the same era Triumph so run with it!

If you do the cross drilled rotors, don't countersink the holes and grab yourself some sintered pads and braided lines. Makes a world of difference on this bike. Without the cross drilling, the sintered pads will load up and you'll loose grip.

You may want to ditch that factory 3-1...it's a killer. You lose enough clearance on that side that you can easily highside from augering that pipe. Been there......
 
You may want to ditch that factory 3-1...it's a killer. You lose enough clearance on that side that you can easily highside from augering that pipe. Been there......
[/quote]

Do you mean I should get an all new exhaust? Would you split and do a 2-1, 1-1? Sorry, but I am new to this, I am not quite sure what you are saying.

Thanks
Brian
 
No worries man, it's all good.....

That header, and more precisely the collector (where all the headpipes come together into the muffler) are positioned such that it's really easy to ground out in a deep corner...hell...with that setup not that deep....
If you hit hard enough it'll try really hard to pitch you over the top and then if you're really unlucky the motorcycle will then dance on your back as you slide along the pavement. Not pretty....

What I always thought would be a badass exhaust on this engine is a 3-3, so one pipe per cylinder, with 3 small bullet mufflers directly under the engine. This engine has such a nice exhaust note that it's begging for some clarity and flow.
 
Swagger said:
No worries man, it's all good.....

That header, and more precisely the collector (where all the headpipes come together into the muffler) are positioned such that it's really easy to ground out in a deep corner...hell...with that setup not that deep....
If you hit hard enough it'll try really hard to pitch you over the top and then if you're really unlucky the motorcycle will then dance on your back as you slide along the pavement. Not pretty....

What I always thought would be a badass exhaust on this engine is a 3-3, so one pipe per cylinder, with 3 small bullet mufflers directly under the engine. This engine has such a nice exhaust note that it's begging for some clarity and flow.
Click to expand...

I hear ya. That is a pretty big knot. How far back would you run the pipe? Is this the type of muffler you're talking about? http://cgi.ebay.com/ebaymotors/Chrome-Motorcycle-Muffler-Shorty-universal_W0QQitemZ150421559505QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item2305d2d8d1
How would you mount them underneath?
 
betz74 said:
I hear ya. That is a pretty big knot. How far back would you run the pipe? Is this the type of muffler you're talking about? http://cgi.ebay.com/ebaymotors/Chrome-Motorcycle-Muffler-Shorty-universal_W0QQitemZ150421559505QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item2305d2d8d1
How would you mount them underneath?
Click to expand...

That's the one. If you could get somebody to weld a tab onto the frame, then you could easily unify the three mufflers with a small bracket that would bolt right to it. Swagger, I can see in my head exactly what you're envisioning. That would be hot!
 
Yeah I think it'd be the bee's knees (thanks Joe...gotta remember that one!)

As Kiley says, once the individual 'bullets' are welded on to the headpipes I'd mock them up and weld a bracket across all three, tucked up out of the way on top of them, and bolt that to the frame.

I've heard a 3-3 on a mildly hotted up 850 and it's a gorgeous sound indeed. Equal parts angry smallblock, insane ferrari plus a little old school aviation. Hard to describe...but imagine a combination of those..spun up to 9 or 10krpm!

Just for giggles, here's what I've been planning for one of my 850s:
-FJ1200 pistons on stock rods with sleeves from LA sleeve = 1038cc and after the domes are turned a target of 10-1 compression.
-Ported head with Kibblewhite +2mm valves and springs with a Delta regrind set
-36mm Mikuni flatslides
-slightly reworked Skorpion 3-1 (remember that triumph exhaust...?)
-lightened flywheel, Barnett clutch

this should be pushing 100hp and 11krpm. I've got everything for an EFI conversion (megasquirt based) but that's a long way off.....

can you tell I dig this engine?
 
Alright, so I made a little progress. Seat is a failure. My styrofoam mold wasn't good enough, when I started sanding bondo and glass I got back down to foam in some spots. I am just going to buy one from roc city. I am playing around with exhaust options. I am just holding the pipes and trying to take the pics so they are a little wonky. I bought pipe and can run them back further. I do like the look of the short pipe but am concerned about the exhaust outlet not being behind me, fumes/heat. Anybody done the shorter pipes? Is this a concern at red-lights and stops?

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Maybe like this?
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I am also going to order some pod filters today if I can figure out the right size. I plan on cutting the side covers back to follow the bar on the frame to expose more open space once the pods are on. I have a spare set from the parts bike in case it doesn't work out.
 
Nice to see another XS triple on the board. Subscribing in hopes of pulling some inspiration. Swagger, what you're saying about the triumph sprint exhaust/carburetors and FJ pistons is NUTS!!! I would love to consult with you about performance mods for mine, but I know it's gonna end up being a low budget resto-mod (Stock carburetors, nothing internal on the motor).

Can you tell me about porting the head? How is it such an easy hp upgrade? I've never heard about it over and yamaha-triples.org (really old forum, not really active anymore)
 
Can you tell me about porting the head? How is it such an easy hp upgrade?
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I'm assuming you know about porting, at least basically, right? Firstly, you will need to remove the cylinder head to be able to get at everything properly and prevent detritus getting into the bores. Then you remove material from the ports, with a tool such as a dremel, enlarging them beyond their stock size. Finish with 240 and finally 400 grit wet/dry sandpaper. These larger ports will allow more gasses to flow through them, increasing the volumetric efficiency of your engine. Thus, with less restriction on both sides, your engine will rev freer and usually a bit higher.

The increased port size may or may not allow for more fuel/air mix to be combusted, but I'm assuming that thats the 'free hp' bit - the ports were undersized to begin with. Once done, you essentially retune the carburettors for the new flow characteristics and off you go! See? Easy :)

- boingk
 
Sorta......

Boinks close, however it's not so much about size of the port (for a street motor) as it is the port's efficiency, as it has to move the fuel/air mixture into the chamber as quickly and smoothly as possible. If you take a look at ANY crossflow head you'll note that everywhere you look you'll find compromises. The two single biggest are the dogleg that all production ports that I know of have, and the valve stem running right thru the center. Production engines are largely 'just get it done' kinda things and they do quite well...astonishingly so when you see how crappy most factory port and combustion chambers are from a performance standpoint.

With an eye to maintaining charge velocity, blend the bowls to the seat (carefully!!!), smooth the small radius of the dogleg and port match to your intake. Get rid of any casting remnants, and you're golden.
If you wanna get really courageous and reach for another 5-6%, spend some time smoothing out the hump around, and the protrusion of the valve guide (a good idea to make sure they are fresh before hand). This will improve the flow of the intake a great deal over stock and still allow the engine to idle and pull strongly from the bottom end. Big ports are great with cams and high compression and big carbs and pipes but if you're keeping it sane you'll get great results from what amounts to a thorough clean up and smoothing. Keep the surfaces of the port and especially the long radius kinda rough (60grit) to avoid pooling and surface adhesion.

On the exhaust side, start with the bowls and work your way out, blending the small radius of the bend toward the pipe outlet and again blend the valve guide and hump in the port floor around it. Finish the exhaust port up to 600 grit...smoother is better on the way out.

How'zat?
 
TTT Did you do the 3-3 exhaust with the shorties? The exhaust manifold looks like it would all be equal length cut. I'm definately considering this route but my only concern would be the rear tire getting overly hot with the exhaust right on it. Tubes could blow.
 
If they're stock there's a smaller diameter inner tube in those head pipes.....
you can cut'm off and go with it, I ran a Jardine muffler set on mine for a while like that.
You won't gain much but you won't lose any either...
 
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