78 XS750 chop first bike build

[TriNortchopz]

Look on the bottom of that lower tree for a 5 digit serial number - I can tell you what year and month it was made. Post more photos of it. Measure the leg from the center of the axle hole to the center of the top pivot hole on the top of the leg - stock length is 24".
Here is my +12 square Durfee girder:

Girders are one of the finest handling front ends and the Durfee is one of the strongest.
Read this from the Durfee site:
It all started back in 1968 when Earl Durfee picked up an old Indian Scout Girder and knew he could do better. You see the better part was easy for Earl because of two big factors.

(1.) By 1968 the popular girder design which was used by Indian Motorcycle Company and was the preferred front suspension design used by the majority of the European motorcycle makers had seen a lot of bad roads (or in some cases, no roads and even bomb craters, motorcycles were used extensively in both WW-1 & 2) and many, many years of hard use. Earl saw that “Road” and “Stress” tests on these old girders pointed out the strengths and weaknesses of the designs. (2.) Earl had spent the last 15 years working in the R&D labs for two well known aircraft and defense contractors, building by hand, the prototypes for the Polaris and Minute-Man missiles. The Metallurgy and welding processes fields in which he had studied, worked-in and knew, had supplied him with the knowledge and tools to bring the girder design up-to-date. Some of the old girders had flaws from the limits of materials and processes available in the 1920’s, 30’s, and 40’s, but by 1968 things had changed and we where in the middle of the “space race”, with all the knowledge and new materials that brought.

But even with the flaws, the good, far outweighed the bad because there are so many great things about girders, some ahead of their time, which convinced him that this was the way to go if you were after a good looking, incredibly strong, light weight and smooth riding motorcycle suspension...
See the rest of the story here:
http://durfeegirder.com/about.html

See more on Chop Cult here; Thread: Picture Thread: Girder Front Ends
http://www.chopcult.com/forum/showthread.php?t=27119

[Rjcinelli]

Thanks for the info TriNortchopz! I believe somebody a few years back told me that girder was a Durfee, I will take some pictures when I get to my buddy's place. As for now, yesterday I got my sleeve fixed up at the machinist and he sent me on my way, 30 mins that's it. Worked on getting the front entrance mounted today, rough idea of what the trail numbers would be and see what I need to do. Back to work today hopefully get some more work done on the frame. that's my buddy Dave who's doing the welding for me.

[Rjcinelli]

Got some more work done, doesn't look like much but it seemed like it's moving along now. Ended up welding the new (clean titled) neck on, had to rake it a bit to get a better trail number. Right now with the current setup I have 6" for trail. From what I read that's about the most you'd want to be at for "safe riding"? Anybody feel free to chime in and tell me otherwise, any info about that is appreciated.

[Rjcinelli]

Go a little more work done yesterday after class, up next I need to put the motor in the frame and make sure it fits before it really gets welded.

[datadavid]

This is just going to be awesome��

[TriNortchopz]

Got some more work done, doesn't look like much but it seemed like it's moving along now. Ended up welding the new (clean titled) neck on, had to rake it a bit to get a better trail number. Right now with the current setup I have 6" for trail. From what I read that's about the most you'd want to be at for "safe riding"? Anybody feel free to chime in and tell me otherwise, any info about that is appreciated.

Great to hear that the other neck ya got worked out - which includes title!
Now that you posted a few more pics, gonna say that is not a Durfee - curve of legs at the bottom and the lower pivot points on the lower tree do not go through the neck post at the bottom.
How are you ensuring alignment?

[Rjcinelli]

Great to hear that the other neck ya got worked out - which includes title!
Now that you posted a few more pics, gonna say that is not a Durfee - curve of legs at the bottom and the lower pivot points on the lower tree do not go through the neck post at the bottom.
How are you ensuring alignment?

Yeah I'm real glad I got the neck and title, a lot less stress now that I know I can register the bike no problem. Hmm I wonder what the girder is if not a Durfee. I set up a home made jig using some square tube and angle iron, it wasn't the prettiest setup but it seemed to have gotten the job done. Didn't take any pictures of that as I was too focused on working on the bike at that point.

I checked the fitment for the motor last night and she will fit right into the frame with oil filter housing removed and then installed before actually bolting the motor in.

[Rjcinelli]

This is just going to be awesome��

Thanks man, a little bit of a slow down on progress since I'm low on cash, but working all day Saturday should help with that. Need to pick up some more 1/8" metal for gussets, and sheet metal for the seat pan. Still not sure what I'm doing about rear fender, maybe a trailer fender from tractor supply that I could modify. I do have a Sportster front fender but I don't see how I could modify that to fit well around the rear tire.

[Rjcinelli]

If anybody has tips on size or placement of gussets, I'm all ears. I was thinking from top tube to each down tube, and maybe a small one on each side of rear hardtail. Does anyone see any strength issues with the design of this frame? First frame build I just want to make sure I am building it strong enough I won't have any issues, a lot of the xs750's I've seen built have bars going down slightly angled on each side of the hardtail portion... Not sure if it's necessary or not but if not I'd rather not do that because I feel like it ruins the clean look.

[TriNortchopz]

Yeah I'm real glad I got the neck and title, a lot less stress now that I know I can register the bike no problem. Hmm I wonder what the girder is if not a Durfee.

Not sure of the girder make...yet, but here are a couple pics of what looks to be the same girder on a '64 Sporty:

[Rjcinelli]

Not sure of the girder make...yet, but here are a couple pics of what looks to be the same girder on a '64 Sporty:

That's a pretty sweet looking sporty, I dig it

[TriNortchopz]

If anybody has tips on size or placement of gussets...from top tube to each down tube...a small one on each side of rear hardtail...see any strength issues with the design of this frame? First frame build I just want to make sure I am building it strong enough I won't have any issues, a lot of the xs750's I've seen built have bars going down slightly angled on each side of the hardtail portion... Not sure if it's necessary or not but if not I'd rather not do that because I feel like it ruins the clean look.

The seat post will tie the upper and lower parts of your frame together - if you don't want one down each side, a single post in the middle would help keep it strong. Another option could be to use the rear of the engine as a stressed member - tie top frame rail to top rear engine mount,(could be a single center post) while ensuring all engine mount tabs/brackets are built strong.

In your research to build your frame, ya musta read these, but may help others too:

How To Build A Chopper Frame!

The Center Post or Seat Post is just a tube welded to the backbone and a crossbrace that runs between the two bottom rails (see the overhead few further on). It's there to make the frame more rigid, and it's worth noting that not all designs include one. If this is the case they clearly need to gain extra rigidity from else where.

http://www.custom-choppers-guide.com...per-frame.html


Old School Chopper Frame Fabrication

Figure 6.3 is probably the most common and the one I personally prefer as it allows easy access for running wiring inside the tube. It seals off the seat post to water intrusion yet the open end of the top tube is naturally sloped to drain. This isn't the easiest connection to make and for that reason it has fallen out of favor by shops doing high volume work but it is a strong connection and permits the builder to easily change the slope angle of the backbone by simply deepening the seat post notch on the back side of the tube. This is the connection method most typically used by custom builders.


http://www.chopperhandbook.com/oldschool1.htm

To place your gussets, the surface of the gusset should be flush with the outer edge of the frame tubing, then welded in place. Say if you place a straightedge across the side of the upper frame rail and the side of the front down tube, the face of the gusset should be flush with the backside of the straightedge...hope that makes sense; like this:



If they are in the centre of the tubing, like this, there will be more stress.



Saw reference to that on this site:

www.choppercompendium.com
grassroots chopper building
http://choppercompendium.com/ccforum/

[Rjcinelli]

The seat post will tie the upper and lower parts of your frame together - if you don't want one down each side, a single post in the middle would help keep it strong. Another option could be to use the rear of the engine as a stressed member - tie top frame rail to top rear engine mount,(could be a single center post) while ensuring all engine mount tabs/brackets are built strong.

In your research to build your frame, ya musta read these, but may help others too:

How To Build A Chopper Frame!

The Center Post or Seat Post is just a tube welded to the backbone and a crossbrace that runs between the two bottom rails (see the overhead few further on). It's there to make the frame more rigid, and it's worth noting that not all designs include one. If this is the case they clearly need to gain extra rigidity from else where.

http://www.custom-choppers-guide.com...per-frame.html


Old School Chopper Frame Fabrication

Figure 6.3 is probably the most common and the one I personally prefer as it allows easy access for running wiring inside the tube. It seals off the seat post to water intrusion yet the open end of the top tube is naturally sloped to drain. This isn't the easiest connection to make and for that reason it has fallen out of favor by shops doing high volume work but it is a strong connection and permits the builder to easily change the slope angle of the backbone by simply deepening the seat post notch on the back side of the tube. This is the connection method most typically used by custom builders.


http://www.chopperhandbook.com/oldschool1.htm

To place your gussets, the surface of the gusset should be flush with the outer edge of the frame tubing, then welded in place. Say if you place a straightedge across the side of the upper frame rail and the side of the front down tube, the face of the gusset should be flush with the backside of the straightedge...hope that makes sense; like this:



If they are in the centre of the tubing, like this, there will be more stress.



Saw reference to that on this site:

www.choppercompendium.com
grassroots chopper building
http://choppercompendium.com/ccforum/

Thanks for that info, I did read a good amount about the frame fab and bracing. Good to brush up on it again. I can't fit a center post in due to the length on my frame, I don't have room for it (see attached picture it's the only one I have with motor semi in there). Not sure if I can figure out a way to make a top motor mount for this motor. I may just end up putting a brace on each side of the rear portion of the hard tail. Hopefully picking up a rear fender tonight, and then I will start the fender/sissy bar/seat pan. Tight on cash until payday on Friday. But I'm plugging away at smaller things.

Maybe I could run a center post slanted towards the back, but I assume if it's slanted it's not going to be as much reinforcement as they are supposed to be (hence why they are usually straight up and down?)

[12w3e4r]

Good thread, righteous build, I dig it when guys fab stuff up and it works and it looks good, and it has style. Keep up the sharp work, looking forward to seeing this completed.

[Rjcinelli]

Good thread, righteous build, I dig it when guys fab stuff up and it works and it looks good, and it has style. Keep up the sharp work, looking forward to seeing this completed.

Thanks man I really appreciate that, doing what I can with what I've got, should be able to get some more work done in the next few days.

Just picked up a fender, bars, and passenger pegs from "nohonestlyitsme" a chopcult member so I'll be getting that stuff done and foam for the seat should be delivered Friday, still have to pick up the sheet metal though

[Irondead]

Subscribed, looking forward to seeing this thing done!

[TriNortchopz]

Thanks for that info, I did read a good amount about the frame fab and bracing. Good to brush up on it again. I can't fit a center post in due to the length on my frame, I don't have room for it (see attached picture it's the only one I have with motor semi in there). Not sure if I can figure out a way to make a top motor mount for this motor. I may just end up putting a brace on each side of the rear portion of the hard tail. Hopefully picking up a rear fender tonight, and then I will start the fender/sissy bar/seat pan. Tight on cash until payday on Friday. But I'm plugging away at smaller things.

Maybe I could run a center post slanted towards the back, but I assume if it's slanted it's not going to be as much reinforcement as they are supposed to be (hence why they are usually straight up and down?)

There are lots of rigid frames out there with a single seat post that is not straight; here is just one example:

To help keep a bent tube strong, just use a thicker walled tubing. It should be able to be bent forward at the top to meet at the backbone intersection- just hard to tell with that one picture with the engine not fully installed.

There is lots to learn by entering 'The Chopper Shed':

"LOTS OF HOW TO CHOPPER PROJECT REPORTS... We build choppers the old school way... craftsmanship and artistry. Photos of our work to give you ideas... Aftermarket parts, parts for Shovels, CB's and XS's, our own unique parts for sale..."

http://www.choppersaustralia.com/for...cc08a1b26b503c


And great fabrication how-to articles here:

Fabrication Articles

+Steering Neck Drawings …Steering necks for bearing cups or built in bearings
+Building a Frame Jig …one version of a jig used to build motorcycle frames
+Frame Tubing …What tubing and steel to use for frame construction
+Coping and Fitting tubes …How to cut and fit frame tubing
+Building a Frame …Part 1---basic bends and rear wishbones
+Building a Frame …Part 2---building the backbone, seat wishbones and rear top wishbones
+Building a Frame …Part 3---Fitting the neck to the down tubes
+Capping Tube Ends … A clean cap for tube ends by the axle plates
+Fabricating Hidden Axle Plates…make your own hidden axle plates
+Hammer Forming …making simple formed parts from sheet metal
+Welding … welding related to frame construction

Tools
+Bending Tube … how to bend tube

Free Plans and Drawings …already started above

Links

http://www.mechwerks.com/MechWerks_home.htm

[Rjcinelli]

There are lots of rigid frames out there with a single seat post that is not straight; here is just one example:

To help keep a bent tube strong, just use a thicker walled tubing. It should be able to be bent forward at the top to meet at the backbone intersection- just hard to tell with that one picture with the engine not fully installed.

There is lots to learn by entering 'The Chopper Shed':

"LOTS OF HOW TO CHOPPER PROJECT REPORTS... We build choppers the old school way... craftsmanship and artistry. Photos of our work to give you ideas... Aftermarket parts, parts for Shovels, CB's and XS's, our own unique parts for sale..."

http://www.choppersaustralia.com/for...cc08a1b26b503c


And great fabrication how-to articles here:

Fabrication Articles

+Steering Neck Drawings …Steering necks for bearing cups or built in bearings
+Building a Frame Jig …one version of a jig used to build motorcycle frames
+Frame Tubing …What tubing and steel to use for frame construction
+Coping and Fitting tubes …How to cut and fit frame tubing
+Building a Frame …Part 1---basic bends and rear wishbones
+Building a Frame …Part 2---building the backbone, seat wishbones and rear top wishbones
+Building a Frame …Part 3---Fitting the neck to the down tubes
+Capping Tube Ends … A clean cap for tube ends by the axle plates
+Fabricating Hidden Axle Plates…make your own hidden axle plates
+Hammer Forming …making simple formed parts from sheet metal
+Welding … welding related to frame construction

Tools
+Bending Tube … how to bend tube

Free Plans and Drawings …already started above

Links

http://www.mechwerks.com/MechWerks_home.htm

Thanks TriNortchopz! I'll be reading this throughout the day during my breaks.

[Rjcinelli]

Well, not as much progress as I had hoped for the time I had but some is better than none. I started the de radius my bobtail fender as well as narrowing it, burning Bondo is definitely not fun to breath in...noted to avoid that next time. Started up with the sissy bar, kept it long for now but will probably shorten it at some point. Oh and I mounted my front tire, ordered a few more parts to keep my bank account empty too.

[TriNortchopz]

Well, not as much progress as I had hoped for the time I had but some is better than none. Started up with the sissy bar, kept it long for now but will probably shorten it at some point. Oh and I mounted my front tire, ordered a few more parts to keep my bank account empty too.

Yup,some progress is better than none. Is that rear wheel an 18"? Have you considered swappin' it to a 16"? Looks like it should work with one from a XS1100:

Thread: swapping just rear wheels between xs750/1100
"Hi, check the thread on this, I have a xs750 rim on a xs1100, 1980, with no modifications needed. So the reverse should also be ok."
http://www.xs11.com/forum/showthread.php?t=26208

And one o' those won't break your account much - just one example:

Price: US $37.00
https://www.ebay.com/itm/78-81-YAMAH...QAAOSwEUdaXl3e