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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.
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.
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:
grassroots chopper building
Last edited by TriNortchopz; 04-28-2018, 12:55 AM.Comment
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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.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.
[ATTACH=CONFIG]83586[/ATTACH]
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.
[ATTACH=CONFIG]83587[/ATTACH]
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:
[ATTACH=CONFIG]83588[/ATTACH]
If they are in the centre of the tubing, like this, there will be more stress.
[ATTACH=CONFIG]83589[/ATTACH]
Saw reference to that on this site:
grassroots chopper building
http://choppercompendium.com/ccforum/
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?)
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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.Comment
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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 thoughComment
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Subscribed, looking forward to seeing this thing done!Comment
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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..."
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
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Thanks TriNortchopz! I'll be reading this throughout the day during my breaks.There are lots of rigid frames out there with a single seat post that is not straight; here is just one example:
[ATTACH=CONFIG]83691[/ATTACH]
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..."
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.htmComment
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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.Comment
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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."
And one o' those won't break your account much - just one example:
Price: US $37.00
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I hadn't thought about going to a 16" but yes it's an 18" in the rear, I just ordered a new rear tire already or I would jump on a 16"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."
And one o' those won't break your account much - just one example:
[ATTACH=CONFIG]83839[/ATTACH]
Price: US $37.00
https://www.ebay.com/itm/78-81-YAMAH...QAAOSwEUdaXl3e
I am still trying to convince my buddy to give me his spoked rear shaft drive wheel from his Suzuki though, tough to convince him!Comment
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If your buddy don't wanna give up his spoked Suzi rear wheel, build your own; just need another trip to your friendly ($20) machinist:
From yamaha-triples.org
2007 Thread:Wire Wheel Options...
Q: "There has to be another option for wire wheels. I am going for a cafe/sport bike look on my project and really want wire. What other options are there?"
Best answer, by SwaggeringPagan:
"There is another option that appears to unexplored by anyone here.
Machining.
When you get down to it, the wheel and more importantly the hub center is just a hunk of cast aluminum. That's it. Nothing there is chipped from unobtainium. I run a small custom machine and prototype shop so I tend to think in this direction when I run into something that doesn't readily show a solution.
Take a look at the hub portion of your rear wheel. Cut away the spokes and rim, chuck it into a lathe and skin it just to the point that you have a flat relatively smooth outer surface and suddenly the possibilities are endless.
Now....say you have an old aluminum motorcycle hub from a spoked rim, especially if it's a spoked/disc brake hub....it'll suit perfectly. Take that nifty old bare hub, knock out the bearings and anything else rattling around inside the axle bore then chuck that lump into your favorite metal chewing lathe and bore the inside out to just 2 thousandths smaller than your previously turned XS hub. While you're making chips, hog out three 1" diameter holes evenly spaced (120 degrees apart for the math whiz out there) in the hub between the spoke rings....these will come in handy later. I would also add a small 1/8" chamfer to the inside edges of the spoke hub.
Toss your now shaved XS hub in the freezer over night and your cored out spoke hub in an old kitchen over for 1/2 hour at 250 degrees to relax it and let it expand a hair. You don't need to melt it damnable thing, just heat it up. When you're ready to mate them, set the chilly XS center on a nice flat surface, grab your toasty spoked section (with proper insulated gloves you goofballs!!) and quickly slide the two together. I like to add about 300 pounds of weight on top (inline with the axle bore) and let the temps equalize. You'll hear all sorts of popping and moaning as the two pieces of metal even out and grab quite securely to each other. If all is right in the world, you've paid your dues and the Gods aren't p***ed at you for even thinking about a step thru scooter (Just for running to the grocery store of course!!) then you should end up with a spoked XS hub.
Remember those holes that go thru the hub and the chamfers? Here's where you bust out the TIG welder (or take it to a qualified welder) and stack teeny tiny dimes until it's welded securely.
I haven't done an XS hub, but I've done the machine work for other bike/wheel combos. It works and in the end, even if you paid a shop to take care of it for you...you'll be money ahead when compared to trying ot dig up a GX hub. As well, it'll probably be lighter......that GX hub is chubby.
Just a thought for those out there who might be up for some fabrication."
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Well, been a little while since I posted on here. Been semi busy with the bike but also got a lot of rain too. I put the motor in the bike, matching front tire to the rear, mounted the rear fender, mounted the seat (temporary until I fab up a proper fitting pan and seat), tacked the passenger pegs on, did the rest of my gaskets on the motor. I think thats about it.
Still need to get a clutch lever for 1" bars, figure out how to set up the rear brake... Struggling with how to run it front brake pedal to the master cylinder, drill frame for gas tank bungs, I need to finish weld everything, figure out an electronics box and where to mount the battery. Hopefully once that's all done I can figure out how I'm going to rewire the bike. I did add in some supports for the frame too.
Criticism, suggestions, tips etc always welcome.
Decided it was time for a nap on the bike once it was mocked up
Started pouring right after we put the roof on the tent, good timing I suppose.Comment
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My buddy who's helping out with the welding trying out the passenger seat, gotta make sure to have a comfy seat for the women ��Comment
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Below are a few threads for electric box building, which may help.
Can you post good pics of the neck area - I'm interested to see how that worked out. And how about a couple of good side views? And a good straight on shot from the front, with the bike level.
What do you mean by, "...figure out how to set up the rear brake... Struggling with how to run it front brake pedal to the master cylinder". Do you mean operate rear brake with handlebar lever?
Steff's xs #7 Electrics Box...
"...I think 1.6mm steel is the best balance between strength. lightness and ease of welding.
Chain is an issue with any electrics box planning. Chain bows out at speed and allowance needs to be made for its position when suspension is fully compressed. A few marks are made on the tyre allowing an extra half an inch to be safe... nothing much more agravating than a rattling chain..."
#8 Simon's Yammy... kicker, electrics box & motor mods...
"Simon liked the idea of using an extinguisher to house the coils and fuses. I suggested a small lithium iron battery so that could be fitted in as well and keep the bike nice and tidy and simple, and this was the road we then took..."
GSX chopper #4 Electrics box...
Step one is always planning and takes time if you are to end up with a job that not only looks good, but will last and most importantly is user friendly.
This is a series of threads that may be of interest to you; a stock KZ750 twin to rigid chop:
Jett's 750 Kawa chopper...
#2: Jett's 750 Kawa chopper #2...
#3: Jett's KZ750 chopper #3 rear guard, sissy bar, tank...
#4: Jett's KZ finished...
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